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Chemistry LibreTexts

17.5: Batteries and Fuel Cells

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  • Page ID 38307

  Learning Objectives

  • Classify batteries as primary or secondary
  • List some of the characteristics and limitations of batteries
  • Provide a general description of a fuel cell

A battery is an electrochemical cell or series of cells that produces an electric current. In principle, any galvanic cell could be used as a battery. An ideal battery would never run down, produce an unchanging voltage, and be capable of withstanding environmental extremes of heat and humidity. Real batteries strike a balance between ideal characteristics and practical limitations. For example, the mass of a car battery is about 18 kg or about 1% of the mass of an average car or light-duty truck. This type of battery would supply nearly unlimited energy if used in a smartphone, but would be rejected for this application because of its mass. Thus, no single battery is “best” and batteries are selected for a particular application, keeping things like the mass of the battery, its cost, reliability, and current capacity in mind. There are two basic types of batteries: primary and secondary. A few batteries of each type are described next.

Visit this site to learn more about batteries.

Primary Batteries

Primary batteries are single-use batteries because they cannot be recharged. A common primary battery is the dry cell (Figure \(\PageIndex{1}\)). The dry cell is a zinc-carbon battery. The zinc can serves as both a container and the negative electrode. The positive electrode is a rod made of carbon that is surrounded by a paste of manganese(IV) oxide, zinc chloride, ammonium chloride, carbon powder, and a small amount of water. The reaction at the anode can be represented as the ordinary oxidation of zinc:

\[\ce{Zn}(s)⟶\ce{Zn^2+}(aq)+\ce{2e-} \hspace{20px} E^\circ_{\ce{Zn^2+/Zn}}=\mathrm{−0.7618\: V} \nonumber \]

The reaction at the cathode is more complicated, in part because more than one reaction occurs. The series of reactions that occurs at the cathode is approximately

\[\ce{2MnO2}(s)+\ce{2NH4Cl}(aq)+\ce{2e-}⟶\ce{Mn2O3}(s)+\ce{2NH3}(aq)+\ce{H2O}(l)+\ce{2Cl-} \nonumber \]

The overall reaction for the zinc–carbon battery can be represented as

\[\ce{2MnO2}(s) + \ce{2NH4Cl}(aq) + \ce{Zn}(s) ⟶ \ce{Zn^2+}(aq) + \ce{Mn2O3}(s) + \ce{2NH3}(aq) + \ce{H2O}(l) + \ce{2Cl-} \nonumber \]

with an overall cell potential which is initially about 1.5 V, but decreases as the battery is used. It is important to remember that the voltage delivered by a battery is the same regardless of the size of a battery. For this reason, D, C, A, AA , and AAA batteries all have the same voltage rating. However, larger batteries can deliver more moles of electrons. As the zinc container oxidizes, its contents eventually leak out, so this type of battery should not be left in any electrical device for extended periods.

Alkaline batteries (Figure \(\PageIndex{2}\)) were developed in the 1950s partly to address some of the performance issues with zinc–carbon dry cells. They are manufactured to be exact replacements for zinc-carbon dry cells. As their name suggests, these types of batteries use alkaline electrolytes, often potassium hydroxide. The reactions are

\[\begin{align*} &\textrm{anode: }\ce{Zn}(s)+\ce{2OH-}(aq)⟶\ce{ZnO}(s)+\ce{H2O}(l)+\ce{2e-} \hspace{40px} E^\circ_\ce{anode}=\mathrm{−1.28\: V}\\ &\underline{\textrm{cathode: }\ce{2MnO2}(s)+\ce{H2O}(l)+\ce{2e-}⟶\ce{Mn2O3}(s)+\ce{2OH-}(aq) \hspace{40px} E^\circ_\ce{cathode}=\mathrm{+0.15\: V}}\\ &\textrm{overall: }\ce{Zn}(s)+\ce{2MnO2}(s)⟶\ce{ZnO}(s)+\ce{Mn2O3}(s) \hspace{40px} E^\circ_\ce{cell}=\mathrm{+1.43\: V} \end{align*} \nonumber \]

An alkaline battery can deliver about three to five times the energy of a zinc-carbon dry cell of similar size. Alkaline batteries are prone to leaking potassium hydroxide, so these should also be removed from devices for long-term storage. While some alkaline batteries are rechargeable, most are not. Attempts to recharge an alkaline battery that is not rechargeable often leads to rupture of the battery and leakage of the potassium hydroxide electrolyte.


Secondary Batteries

Secondary batteries are rechargeable. These are the types of batteries found in devices such as smartphones, electronic tablets, and automobiles.

Nickel-cadmium, or NiCd, batteries (Figure \(\PageIndex{3}\)) consist of a nickel-plated cathode, cadmium-plated anode, and a potassium hydroxide electrode. The positive and negative plates, which are prevented from shorting by the separator, are rolled together and put into the case. This is a “jelly-roll” design and allows the NiCd cell to deliver much more current than a similar-sized alkaline battery. The reactions are

\[\begin{align*} &\textrm{anode: }\ce{Cd}(s)+\ce{2OH-}(aq)⟶\ce{Cd(OH)2}(s)+\ce{2e-}\\ &\underline{\textrm{cathode: }\ce{NiO2}(s)+\ce{2H2O}(l)+\ce{2e-}⟶\ce{Ni(OH)2}(s)+\ce{2OH-}(aq)}\\ &\textrm{overall: }\ce{Cd}(s)+\ce{NiO2}(s)+\ce{2H2O}(l)⟶\ce{Cd(OH)2}(s)+\ce{Ni(OH)2}(s) \end{align*} \nonumber \]

The voltage is about 1.2 V to 1.25 V as the battery discharges. When properly treated, a NiCd battery can be recharged about 1000 times. Cadmium is a toxic heavy metal so NiCd batteries should never be opened or put into the regular trash.


Lithium ion batteries (Figure \(\PageIndex{4}\)) are among the most popular rechargeable batteries and are used in many portable electronic devices. The reactions are

\[\begin{align*} &\textrm{anode: }\ce{LiCoO2}⇌\ce{Li}_{1-x}\ce{CoO2}+x\ce{Li+}+x\ce{e-}\\ &\textrm{cathode: }x\ce{Li+}+x\ce{e-}+x\ce{C6}⇌x\ce{LiC6}\\ &\overline{\textrm{overall: }\ce{LiCoO2}+x\ce{C6}⇌\ce{Li}_{1-x}\ce{CoO2}+x\ce{LiC6}} \end{align*} \nonumber \]

With the coefficients representing moles, x is no more than about 0.5 moles. The battery voltage is about 3.7 V. Lithium batteries are popular because they can provide a large amount current, are lighter than comparable batteries of other types, produce a nearly constant voltage as they discharge, and only slowly lose their charge when stored.


The lead acid battery (Figure \(\PageIndex{5}\)) is the type of secondary battery used in your automobile. It is inexpensive and capable of producing the high current required by automobile starter motors. The reactions for a lead acid battery are

\[\begin{align*} &\textrm{anode: }\ce{Pb}(s)+\ce{HSO4-}(aq)⟶\ce{PbSO4}(s)+\ce{H+}(aq)+\ce{2e-}\\ &\underline{\textrm{cathode: } \ce{PbO2}(s)+\ce{HSO4-}(aq)+\ce{3H+}(aq)+\ce{2e-}⟶\ce{PbSO4}(s)+\ce{2H2O}(l)}\\ &\textrm{overall: }\ce{Pb}(s)+\ce{PbO2}(s)+\ce{2H2SO4}(aq)⟶\ce{2PbSO4}(s)+\ce{2H2O}(l) \end{align*} \nonumber \]

Each cell produces 2 V, so six cells are connected in series to produce a 12-V car battery. Lead acid batteries are heavy and contain a caustic liquid electrolyte, but are often still the battery of choice because of their high current density. Since these batteries contain a significant amount of lead, they must always be disposed of properly.


A fuel cell is a device that converts chemical energy into electrical energy. Fuel cells are similar to batteries but require a continuous source of fuel, often hydrogen. They will continue to produce electricity as long as fuel is available. Hydrogen fuel cells have been used to supply power for satellites, space capsules, automobiles, boats, and submarines (Figure \(\PageIndex{6}\)).


In a hydrogen fuel cell, the reactions are

\[\begin{align*} &\textrm{anode: }\ce{2H2 + 2O^2- ⟶ 2H2O + 4e-}\\ &\underline{\textrm{cathode: }\ce{O2 + 4e- ⟶ 2O^2-}\hspace{55px}}\\ &\textrm{overall: }\ce{2H2 + O2 ⟶ 2H2O} \end{align*} \nonumber \]

The voltage is about 0.9 V. The efficiency of fuel cells is typically about 40% to 60%, which is higher than the typical internal combustion engine (25% to 35%) and, in the case of the hydrogen fuel cell, produces only water as exhaust. Currently, fuel cells are rather expensive and contain features that cause them to fail after a relatively short time.

Batteries are galvanic cells, or a series of cells, that produce an electric current. When cells are combined into batteries, the potential of the battery is an integer multiple of the potential of a single cell. There are two basic types of batteries: primary and secondary. Primary batteries are “single use” and cannot be recharged. Dry cells and (most) alkaline batteries are examples of primary batteries. The second type is rechargeable and is called a secondary battery. Examples of secondary batteries include nickel-cadmium (NiCd), lead acid, and lithium ion batteries. Fuel cells are similar to batteries in that they generate an electrical current, but require continuous addition of fuel and oxidizer. The hydrogen fuel cell uses hydrogen and oxygen from the air to produce water, and is generally more efficient than internal combustion engines.

  • Chemistry Articles
  • Battery Types

Types Of Battery - Primary cell & Secondary cell

What is a battery.

A Battery is a device consisting of one or more electrical cells that convert chemical energy into electrical energy. Every battery is basically a galvanic cell where redox reactions take place between two electrodes which act as the source of the chemical energy.

Types Of Battery

Battery types

Batteries can be broadly divided into two major types.

  • Primary Cell / Primary battery
  • Secondary Cell / Secondary battery

Based on the application of the battery, they can be classified again. They are:

Household Batteries

These are the types of batteries which are more likely to be known to the common man. They find uses in a wide range of household appliances (such as torches, clocks, and cameras). These batteries can be further classified into two subcategories:

  • Rechargeable batteries Nickel Examples: Cadmium batteries, Lithium-Ion
  • Non-rechargeable batteries Examples: Silver oxide, Alkaline & carbon zinc

Industrial Batteries

Vehicle batteries, primary cell.

primary battery

These are batteries where the redox reactions proceed in only one direction. The reactants in these batteries are consumed after a certain period of time, rendering them dead. A primary battery cannot be used once the chemicals inside it are exhausted.

An example of a primary battery is the dry cell – the household battery that commonly used to power TV remotes, clocks, and other devices. In such cells, a zinc container acts as the anode and a carbon rod acts as the cathode. A powdered mixture of manganese dioxide and carbon is placed around the cathode. The space left in between the container and the rod are filled with a moist paste of ammonium chloride and zinc chloride.

The redox reaction that takes place in these cells is:

Zn(s) –> Zn 2+ (aq) + 2e –

2e – + 2 NH 4 + (aq) –> 2 NH 3 (g) + H 2 (g)

2 NH 3 (g) +Zn 2+ (aq) –> [Zn (NH 3 ) 2 ] 2+ (aq)

H 2 (g) + 2 MnO 2 (S) –> Mn 2 O 3 (S) + H 2 O (l)

Thus, the overall cell equation is:

Zn(s) + 2 NH 4 + (aq) + 2 MnO 2 (S) –> [Zn(NH 3 ) 2 ] 2+ (aq) + Mn 2 O 3 (S) + H 2 O (l)

Another example of the primary cell is the mercury cell, where a zinc-mercury amalgam is used as an anode and carbon is used as a cathode. A paste of HgO is used as an electrolyte. These cells are used only in devices that require a relatively low supply of electric current (such as hearing aids and watches).

Secondary Cell

These are batteries that can be recharged after use by passing current through the electrodes in the opposite direction, i.e. from the negative terminal to the positive terminal.

secondary battery

For example, a lead storage battery that is used in automobiles and inverters can be recharged a limited number of times. The lead storage battery consists of a lead anode and the cathode is a lead grid packed with lead dioxide. Sulphuric acid with a concentration of 38% is used as an electrolyte. The oxidation and reduction reactions involved in this process are listed below.

Pb –> Pb 2+ + 2 e –

Pb+ SO 4 2– –> PbSO 4 (electrode) + 2 e –

2 e – + PbO 2 + 4 H + –> Pb 2+ + 2 H 2 O

2 e – + PbO 2 + 4 H + + SO 4 2- –> PbSO 4 (electrode) + 2 H 2 O

In order to recharge these batteries, the charge is transferred in the opposite direction and the reaction is reversed, thus converting PbSO 4 back to Pb and PbO 2 .

Another example of the secondary cell is the nickel-cadmium cell. These cells have high storage capacities and their lifespan is relatively long (compared to other secondary cells). However, they are difficult to manufacture and maintain.

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  • Difference between primary and secondary cell
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Engineers Garage

Introduction to batteries and their types

By Ayush Jain

What is a Battery?

A battery is an electrochemical device that can store energy in the form of chemical energy. It translates to electric energy when the battery is connected in a circuit due to the flow of electrons because of the specific placement of chemicals. It was invented by Alessandro Volta, whereas Gaston Plante invented the rechargeable battery.

The battery consists of three elements: the negative side, the positive side, and electrolyte (the chemical which reacts with both sides), as shown in the image below. The electrolyte is used as an electron transportation medium between the anode and cathode.

It works due to electrochemical reactions called oxidation and reduction. In this reaction, electrons flow from one side to another side when the external circuit is connected to the anode and cathode.

assignment of batteries

General battery diagram.

The battery’s chemical composition can vary for different applications, specifications, sizes, etc., which are explained below in types of batteries.

Battery applications

The battery is used in applications where energy is required to be stored for future purposes. Portable, emergency, and low-power devices generally use batteries. A portable device, such as a mobile laptop, has a battery to use anywhere you want. An emergency device like an inverter, torch, etc., is used when there is no electricity. Low power devices like watches, oximeter, etc., can run for a long time after replacing the battery. The mains supply is not suitable for all situations.

The requirement of a battery depends upon various conditions like how much power is needed or what device portability is. But what about the wall watch? Why is this not connected to a socket?

The wall watch consumes very little power. A 1.2v battery can make it run almost for two years, but this is not the main reason. The watch should be powered up every instant to get the correct time; this can be done by battery. A single hindrance in power will cause a delay in time. That’s why it is designed to work with less power thereby allowing the watch to run for a longer period and making the battery an efficient way to supply power constantly.

Let’s take another example. Generally, a vehicle works on petrol. In a self-start vehicle, the initial ignition of the engine is done by an ignition coil and a motor. The motor is used to reach specific rpm of the engine, and the ignition coil is used as a source of ignition. This vehicle ignition coil draws about four Amps. This current can vary among different manufacturers, and there is lots of space in the vehicle. That’s why to fill the higher current requirement lead-acid battery is perfect for it.

assignment of batteries

Vehicle ignition.

From the above example, we can say that the use of batteries depends upon condition and application.

Types of Batteries

Based on functionality, there are two types of batteries available in the market.

  • Primary Batteries.
  • Secondary Batteries.  

Primary Batteries

The batteries made for one-time use only and unable to recharge, are called primary batteries . This type of battery is thrown away after use. It is also known as non-rechargeable batteries . It’s a very simple and convenient source of power for portable devices like a watch, camera, torch, etc. The battery comes in a standard size, as given below.

assignment of batteries

The standard size of the battery

These batteries are cheap, small, lightweight, and there is no or low maintenance required.

Some common primary batteries

  • Alkaline battery

The alkaline battery mainly consists of zinc and manganese dioxide as electrodes. The alkaline electrolyte is used as either potassium or sodium hydroxide. As you can see in the image below, the outer casing is a steel drum, and there is a cap on a drum which is a positive terminal. Inside this drum, the fine-grained manganese dioxide (MnO2) power mixed with coal dust is molted, as shown in the image. This molted mixture is part of the cathode in an alkaline battery. There is another powder filled inside the cathode powder, which is Zinc powder with potassium hydroxide. The Zinc (Zn) powder is part of the anode in an alkaline battery. Both powders are separated by a paper separator. The paper separator is soaked with potassium hydroxide, an electrolyte between the cathode (MnO2) and anode (Zn). The metallic brass pin is inserted along with the center axis of the alkaline battery, which is a negative collector pin. The pin is in touch with the metallic end. There is a plastic cover, which separates the metallic end and the steel drum. The metallic end is the negative terminal of an alkaline battery.

assignment of batteries

Alkaline Battery

This battery is used where low voltage is required. One single cell can provide 1.5V. This is very cheap, so it can reduce the cost of the product. Every clock which hangs on the wall or remotes that control your TV and AC works on these alkaline batteries.

  • Button cell battery

As you can see, the button cell is in the form of a button leading the body to be the cathode, and the anode is insulated at the top of the battery. The body is made of nickel-platted stainless steel – a positive terminal of the coin cell. At the top of the CAN, you can see a negative terminal cap. Both the CAN and the top cap are separated by a gasket made of insulator material. Inside the battery, there are two materials: Lithium metal and manganese dioxide, separated by a separator. The electrolyte used in the battery is lithium salt in an organic solvent.

assignment of batteries

Button cell (Source)

Button or coin cells can be seen in watches in different sizes. This also comes in the alkaline batteries category because it comprises three substances- lithium as anode and manganese dioxide as a cathode, and alkaline as an electrolyte. These batteries are used to power small devices like watches, pocket calculator RAM, etc.

Secondary Batteries

The battery which is made for reusable purposes by recharging are called secondary batteries . They are also called rechargeable batteries . They have the same electrochemical reaction as alkaline batteries, but the electrochemical reaction can be reversed. This type of battery is used for portable devices like mobile phones, laptops, electric vehicles, etc. Also, a rechargeable battery is used with an inverter which stores power to supply our household devices.

Some common secondary batteries

  • Lead-Acid batteries

The lead-acid battery container is made up of hard rubber of a bituminous compound. The container obtains dilute sulfuric acid, which is an electrolyte. The lead plates made of grid form are dipped in the electrolyte. The positive plate of the lead-acid battery is made of lead peroxide(PbO2). This is a dark brown hard, and brittle substance. The negative plate is made of pure lead in soft sponge conditions. A separator separates both electrodes. This separator can be made of cellulose, polyvinyl chloride, organic rubber, and polyolefins. The positive and negative are connected on the top of the battery, which is the outer positive and negative terminal to connect the load or device. There is a filter cap with a small hole in the center. The filter cap provides access for adding electrolytes, and the holes allow gases to be vented to the atmosphere.

assignment of batteries

Lead Acid Battery ( Source )

These batteries are low cost, reliable, larger, and are heavily weighted.  It is mostly used in heavy-duty applications because it is not portable due to its weight and size. It is used in non-portable applications like solar-panel energy storage, vehicle ignition and lights, backup power, and load leveling in power generation and distribution.  

  • Nickel-Cadmium batteries

A Nickel-cadmium battery (Ni-Cd or NiCad battery) is made of nickel oxide hydroxide as cathode and metallic cadmium as an anode. Firstly, a layer of nickel oxide NiO2 is kept around the redox. This layer act as a cathode. Above this cathode layer, a separator of KOH or NaOH is made to provide OH ions. After this layer, the cadmium layer act as an anode of the ni-cd battery. Nickel layer act as a positive electrode and cadmium act as a negative electrode. The arrangement of the layer is rolled in a cylindrical shape in a case. The outer case is made of metal with a sealing plate and safety valve, which allow it to realize gasses out of the container. A cap on the top of the cell is insulated by a gasket, which acts as a positive of the ni-cd battery.

assignment of batteries

Nickel-Cadmium Battery. ( Source )

These batteries are relatively less in cost, with toxic materials and a high self-discharge rate. It has a higher number of charging and discharging cycles. The energy density is higher than lead-acid batteries. It is smaller, lighter, and available in different sizes like alkaline batteries. It is generally used in low-cost devices like toys, solar light or cordless phones, etc.

  • Nickel-Metal Hydride batteries

  Nickel metal hydride battery (NiMH or Ni-MH) is made of Nickel oxide hydroxide as cathode and hydrogen-absorbing alloy as an Anode. The construction of the Ni-MH battery is the same as the Ni-cd battery. The Nickel oxide hydroxide layer and hydrogen-absorbing alloy are rolled with the separator of KOH or NaOH. The outer metal case Act as a negative terminal is connected with hydrogen-absorbing alloy. The cap on the top of the cell acts as a positive terminal and is connected with Nickel oxide hydroxide. An insulating seal ring or gasket separates both negative and positive terminals.

assignment of batteries

Nickel-Metal Hydride Battery. ( Source )

Compared to Ni-Cd, these are more efficient with higher energy density, less toxic, and lower self-discharge rate. It is relatively expensive when compared to Ni-Cd. It has resistance to over-charging and over-discharging. It isn’t very easy to charge, and some manufacturers provide their specific chargers.

  • Lithium-ion batteries

  Lithium-ion batteries have anode made of graphite and cathode made of lithium metal oxide. The lithium salt as an organic solvent is used as an electrolyte. When the battery is connected to the circuit or load, lithium-ion migrates from the negative electrode to the positive electrode.

In the image below, the construction of the li-ion battery is similar to the Ni-Cd and Ni-NH batteries, apart from materials. The lithium metal oxide is coated on aluminum foil which is the positive electrode. The graphite is coated on copper foil which is the negative electrode. Both foils are rolled in a cylindrical shape with a separator between them. The spectator is soaked with electrolyte material which generally is lithium salt as an organic solvent. The outer metal casing is negative, and the top cap is the positive terminal. Both are separated by a gasket, which is made of insulating material.

assignment of batteries

Lithium-Ion Battery. ( Source )

Lithium-ion batteries are used in mobiles, laptops, and many portable devices. It is also used in the military and aerospace due to its lightweight nature. It has a higher energy density and low self-discharge compared to other types of batteries. It is also available in various sizes. Its single-cell voltage is higher.  These have a significant risk of explosion when it is short-circuited or externally damaged.

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  • Two-Cell Battery

Hands-on Activity Two-Cell Battery

Grade Level: 4 (3-5)

Time Required: 1 hour

Expendable Cost/Group: US $3.50

Group Size: 3

Activity Dependency: None

Subject Areas: Algebra, Physical Science

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Engineers help shape a safer future

For some engineers, designing amazing batteries is their specialty. Electrical engineers continually conduct research to improve the efficiency of rechargeable batteries that are used in laptops, cell phones, digital cameras and electric cars. Some engineers are developing extremely tiny batteries that are smaller than the width of a human hair. These batteries provide power for microelectromechanical systems (MEMS) located in devices for specialized use in the medical and aerospace industries.

After this activity, students should be able to:

  • Describe the energy transformations that take place when a battery is connected in a circuit.
  • Explain that an electrolyte is needed for a battery to produce current electricity.
  • Construct and interpret a graph of current produced by a battery as a function of electrolyte concentration.

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Each group needs:

  • 2 pieces aluminum foil: 8 in x 12 in (20 cm x 30 cm)
  • 2 wide-mouth glass jars (must be able to hold at least 150 ml)
  • 2 small paper cups (such as Dixie cups), cut at ¾ in from the cup bottom, or 2 plastic caps from milk jugs
  • 3 pieces (one: 12 in [30 cm] and two: 31.5 in [80 cm]) of non-insulated copper wire (gauge AWG 20) (available at most hardware stores); a total of 75 in (200 cm) per group. Or, if you have insulated wire, it will work if you strip the insulation off the ends.
  • masking tape
  • wire cutters
  • marking pens
  • Two-Cell Battery Worksheet

For a Battery Testing Station for the entire class to share:

  • containers for the electrolyte solutions (must be able to hold at least 150 ml); wide-mouth glass jars work well
  • electrolyte solutions (make in advance with water and vinegar, citrus juice [such as lemon] or salt; see Procedure section)
  • a few graduated cylinders (10–25 ml) or liquid measuring cups or jars with volumes marked on the side
  • 3 pairs of safety glasses or goggles
  • 1 DC ammeter (to measure current in amperes) (available at most hardware or electronics shops)
  • paper towels

For a Cleaning Station for the entire class to share:

  • water and sink, or, if no drain is available, a large empty container to collect the used electrolyte solutions
  • (optional) paper towels

(Before starting the activity, ask students to brainstorm.) From where does electricity come? (Possible ideas: A wall outlet, power plant, photovoltaic/solar cells, batteries, etc. If no student mentions a battery, ask them the next question.) Do you think electricity can come from a battery? (Answer: Yes) Have you ever wondered what is inside of a battery? How do engineers decide what liquid or paste to use in this can full of chemicals?

What is inside a battery that helps produce current electricity? (Possible ideas: Chemicals, paste or a bunch of electrons.) Well, inside a battery are two metal plates or posts called electrodes where chemical reactions take place and produce electrons. Also inside is a solution called an electrolyte, which allows charge to move in the solution and balances the movement of electrons. During today's activity, you will create your own two-cell batteries and learn how engineers determine what type of electrolyte is best to use in batteries!

(Show students a battery.) Have you ever looked closely at a battery and seen a small number with the letter "V" next to it? What does the letter represent? (Answer: Volts) During today's activity, you will learn how to determine the number of volts a battery produces.

(Remind students.) Remember what you've learned about atoms...? Atoms are made of smaller parts called protons, neutrons and electrons. The electrons carry a negative electric charge , move from atom to atom, and create current electricity .

How many different applications can you think of that use batteries? (Listen to student ideas.) How do you think that engineers might be involved with batteries? (Listen to student ideas.) Well, engineers design all the types of batteries that we use every day. Some engineers conduct research to improve the efficiency of rechargeable batteries. Other engineers work to improve rechargeable lithium batteries that are used for laptops, digital cameras and electric cars so they last longer and are able to be re-charged for additional cycles. Other engineers also are developing an extremely small battery to power microelectromechanical systems (MEMS). MEMS devices, which are used in medical and aerospace industries, are smaller than the width of a human hair. That's a small battery!

A typical wet-cell battery has two terminals, a liquid electrolyte and two electrodes, called the anode and the cathode.

During this activity, students make their own two-cell batteries with aluminum and copper electrodes immersed in a prepared electrolyte solution. We use two cells connected in series (one after the other) to make this battery because the voltage produced by each cell is so low; connecting the two cells in series doubles the voltage produced.

In each cell, the aluminum foil serves as the anode. The aluminum foil oxidizes, producing aluminum cations (Al 3+ ) that go into the solution and leave the aluminum electrode with excess electrons. These electrons move through the foil in container A, up to the copper wire (which is connected to the ammeter), and through the ammeter to the coiled copper wire in container B.

In each cell, the copper wire is the cathode. Electrons combine with copper cations in the solution and form elemental copper. The same oxidation process takes place at the aluminum anode in container B as was described for container A. Therefore, there is a movement of electrons from the foil in container B through the copper wire to the coiled wire in container A. Again, these electrons combine with the copper cations in the solution in container A. The electrolyte in both cells serves to balance the movement of electrons by providing ions. Each cell produces a voltage of about 2 V, so the total voltage for the battery is about 4 V.

Before the Activity

  • Cut two 8 in x 12 in (20 cm x 30 cm) pieces of aluminum foil for each team.
  • Cut one 12 in (30 cm) piece and two 31.5 in (80 cm) pieces of wire for each team. Note that insulated wire can be used, as long as it is stripped at the ends.
  • Decide which electrolytes to use. (Suggestion: For a class of 27 students working in nine teams of three students each, use three different electrolytes [vinegar, citrus juice, salt] in three different strengths [weak, medium, strong].)
  • Prepare the electrolyte solutions, making about 400 mL of each solution. Make sure to label them. The whole class can use the same type of solution at different strengths, or different teams can have different types of solutions at a range of strengths (see examples below):
  • Weak solution : 5 ml (~1 teaspoon) of [vinegar or citrus juice or salt] for every 100 ml water
  • Medium solution : 15 ml (~1 tablespoon) of [vinegar or citrus juice or salt] for every 100 ml water
  • Strong solution : 40 ml (~2.5 tablespoon) of [vinegar or citrus juice or salt] for every 100 ml water

If the number of teams is not a multiple of three (one team using the weak solution, one using the medium solution, and one using the strong solution), prepare more electrolyte solutions for the remaining teams, making them incrementally stronger.

  • Prepare a Battery Testing Station for the entire class to use: 3 pairs of goggles, a DC ammeter, graduated cylinders, all the containers of prepared electrolyte and paper towels.
  • Set up a Cleaning Station.
  • Make copies of the Two-Cell Battery Worksheet , one per team.

With the Students

Have each team construct its two-cell battery at a desk. After all the groups have finished, gather the class around the battery testing station to observe what happens when electrolyte is added to each team's battery.

Constructing the Battery:

  • Put a piece of tape on each glass container. Label one container A and the other B.
  • Have students roll each piece of foil so the long side of the roll is about 12 in (30 cm). Crumple about 1/4 of one end on each roll.
  • Place one aluminum foil roll in each container, placing the crumpled end on the bottom of the container. Carefully flatten the rolled part of the foil against the side of each container.
  • Place a paper cup bottom (or milk cap) on top of the crumpled foil in each container; the aluminum foil column should go up and around the side of the paper cup (or milk cap) (see Figure 1).
  • Carefully wind one end of the 12 in (30 cm) piece of copper wire around the top of the foil roll in container A. Make a couple winds with the wire to get a good connection. Leave the other end of the wire free.

A photograph shows the bottom of a glass jar containing a rolled aluminum foil column bent at a 90-degree angle across the bottom of the jar. Past the bend, some of the foil is crumpled against the bottom of the glass jar. On top of the crumpled aluminum foil is an upside down paper cup bottom.

  • Coil about 22-24 in (55-60 cm) of the 31.5 in (80 cm) piece of wire into a ball. Place this ball on top of the paper cup bottom in container B. Make sure the copper wire is not touching the aluminum foil.
  • Coil about 22-24 in (55-60 cm) of the second 31.5 in (80 cm) piece of wire into a ball. Place this ball on top of the paper cup bottom in container A. Make sure the copper wire is not touching the aluminum foil.
  • Carefully wind the free end of the third piece of copper wire (the 31.5 in wire in container A) around the top of the foil roll in container B. Again, make a couple winds with the wire to get a good connection.

A photograph of the activity set up. On the left, a glass container marked "A" holds a rolled aluminum foil column with a 90-degree angle and the part of the foil after the angle crumpled against the bottom of the glass jar. On top of the crumpled piece of aluminum is an upside down bottom of a small paper cup. A coiled piece of copper wire sits on top of the paper cup bottom. The other side of the copper wire is connected to the top of the aluminum foil column that is situated in a second glass container, labeled "B," located to the right of container "A." Container B has the same setup described for container A, however, the coiled copper wire on top of the paper cup leads out of the container and is not connected to anything.

Testing the Battery. Repeat steps 9–15 for each team.

  • Have students wear goggles when they test their batteries.
  • Connect the free end of the wire from container A to one of the ammeter connections.
  • Connect the free end of the wire from container B to the other ammeter connection.
  • Obtain an electrolyte solution. Pour about 50 ml of the electrolyte solution into container A and about 50 ml of the same solution into container B. The solution should cover the wire coils in both containers completely; if not, carefully add more of the solution.
  • Measure the current produced by the battery using a DC ammeter. Have one student from each team record the electrolyte concentration and current.

A photograph displays the completed battery (described in Figure 2) being tested with a lemon juice/water electrolyte solution.  Container A and container B are filled with just enough of the electrolyte solution to cover the coiled copper wire.  An ammeter is connected to the two copper wires that are wrapped around the top of the aluminum foil columns. The ammeter reads 0.06 Amps.

  • Disconnect the wires from the ammeter.
  • Pour the electrolyte solution back into its correct source container.
  • After all students have tested their batteries, have teams disassemble their batteries. Have one member of each team take its materials to the Cleaning Station. Students should gently rinse containers A and B with a small amount of water. Pour this water in the sink or into a container provided for this purpose.
  • Have teams report the electrolyte concentration and current produced by their batteries on the classroom board.
  • In teams, have students complete the Two-Cell Battery Worksheet .
  • As a math exercise, using the chart on the Two-Cell Battery Worksheet , have students construct graphs of current as a function of concentration and use the graphs to predict what the current might be at intermediate electrolyte concentrations.

ammeter: An instrument that measures electric current in amperes.

cation: An ion or group of ions having a positive charge and characteristically moving toward the negative electrode in electrolysis.

electrolyte: A material that dissolves in water, producing a solution that conducts electricity.

ion: An atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons.

Pre-Activity Assessment

Brainstorming: In small groups, have students engage in open discussion. Remind students that in brainstorming, no idea or suggestion is "silly." All ideas should be respectfully heard. Encourage wild ideas and discourage criticism of any ideas. Ask the students:

  • From where does electricity come? (Possible answers: A wall outlet, power plant, photovoltaic/solar cells, batteries, etc.)
  • What is inside batteries that helps produce current electricity? (Possible answers: Chemicals, paste, or a bunch of electrons.)

Activity Embedded Assessment

Question/Answer: Ask students questions and have them raise their hands to respond. Write answers on the board and discuss as a class.

  • What causes the needle to move on a DC ammeter? (Answer: Chemical energy in the battery is converted to electrical energy in the copper wire, which causes the needle to move on a DC ammeter.)

Worksheet/Pairs Check: Have one student from each team record on the board the electrolyte concentration and current while using the DC ammeter. Have students work in groups to answer questions on the Two-Cell Battery Worksheet. After student teams finish their worksheets, have them compare answers with a peer group, giving all students time to finish their worksheets.

Post-Activity Assessment

Question/Answer: Ask students questions and have them raise their hands to respond. Write answers on the board and discuss as a class. Ask the students:

  • What is the role of the aluminum foil and copper wire in the battery circuit? (Answer: Copper and aluminum are the electrodes in the battery. Chemical reactions take place at the electrodes producing electrons that move through the wires.)
  • Was there an ammeter reading for the battery before you added electrolyte? (Answer: No. There is no ammeter reading for the battery until you add the electrolyte.)
  • Which electrolyte solution produced the highest current reading? (Note: This depends on which electrolytes you use and on their concentration. Using a strong salt solution should give the highest current. A strong vinegar solution produces the next highest current.)
  • Why do we need an electrolyte in a battery? (Answer: The electrolyte allows charge to move in the solution balancing the movement of electrons.)

Safety Issues

  • Require students to wear safety goggles at the Battery Testing Station in case any electrolyte splashes.
  • Watch that students do not play with the copper wire, so they do not cut themselves or others.

Make sure students do not touch the copper wire and the aluminum foil. If the copper wire and aluminum foil contact each other, it produces a short circuit (which is a low-resistance connection established by accident between two points in an electric circuit, causing the current to flow through the area of low resistance [aluminum to copper wire] and bypass the intended circuit [the solution]). If a short circuit is created the students will not get any current reading (0.00 A) or will not obtain an accurate current reading on the DC ammeter for the solution.

Be sure to prepare enough electrolyte solution. Some containers may need up to 200 mL of solution, depending on their size.

After students have taken their last readings, have them each add a teaspoon of baking soda (a base) to a container with an acidic solution. Have them record what happens to the ammeter reading.

Connect several batteries together in series using wires with alligator clips. How many batteries does it take to light a #40 light bulb?

  • For lower grades, conduct the activity as described, but do not complete the worksheet. Instead, have students measure and record the battery current for each electrolyte using a DC ammeter. Then, have them explain which electrolyte concentration produces a battery with the highest current.
  • For higher grades, have students measure current using a DC ammeter, complete the worksheet, and create graphs of current as a function of electrolyte concentration. Use the graph to predict the current at intermediate electrolyte concentrations. Ask students to draw conclusions about how the current produced by a battery depends on the concentration of the electrolyte in the battery.

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Making a "Wet Cell" Battery, Grade 9 Lesson Plan, Renewable Energy, The Infinite Power of Texas. Accessed March 2004. Formerly available at


Supporting program, acknowledgements.

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: October 22, 2021

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Introduction to solid-state chemistry, bonus lecture 2: the chemistry of batteries.

Description: Discussion of energy storage, electrical storage, and the chemistry of batteries.

Instructor: Jeffrey C. Grossman

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6: Batteries

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  • Dissemination of IT for the Promotion of Materials Science (DoITPoMS)
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Learning Objectives

  • In this TLP, it is aimed to consider the basic electrochemical principles involved in the operation, design and use of batteries and the technical criteria relevant for battery selection.
  • 6.1: Introduction
  • 6.2: Basic principles
  • 6.3: Thermodynamics and kinetics
  • 6.4: Primary batteries
  • 6.5.1: Zinc/carbon batteries
  • 6.6.1: Alkaline/manganese oxide batteries
  • 6.7: Questions
  • 6.8.1: Zinc/silver oxide batteries
  • 6.9: Secondary batteries
  • 6.11: Lithium batteries
  • 6.12: Battery characteristics
  • 6.13: The future


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Basic Battery Operation

The basis for a battery operation is the exchange of electrons between two chemical reactions, an oxidation reaction and a reduction reaction. The key aspect of a battery which differentiates it from other oxidation/reduction reactions (such as rusting processes, etc) is that the oxidation and reduction reaction are physically separated. When the reactions are physically separated, a load can be inserted between the two reactions. The electrochemical potential difference between the two batteries corresponds to the voltage of the battery which drives the load, and the exchange of electrons between the two reactions corresponds to the current that passes through the load. The components of a battery, which are shown in the figure below, and consist of an electrode and electrolyte for both the reduction and oxidation reaction, a means to transfer electrons between the reduction and oxidation reaction (usually this is accomplished by a wire connected to each electrode) and a means to exchange charged ions between the two reactions.

battery schematic a

Schematic of a battery in which (a) the electrolyte of the reduction and oxidation reaction are different and (b) the electrolyte is the same for both reactions.

The key components which determines many of the basic properties of the battery are the materials used for the electrode and electrolyte for both the oxidation and reduction reactions. The electrode is the physical location where the core of the redox reaction – the transfer of electrons – takes place. In many battery systems, including lead acid and alkaline batteries, the electrode is not only where the electron transfer takes places, but is also a component in the chemical reaction that either uses or produces the electron. However, in other battery systems (such as fuel cells) the electrode material is itself inert and is only the site for the electron transfer from one reactant to another. For a discharging battery, the electrode at which the oxidation reaction occurs is called the anode and by definition has a positive voltage, and the electrode at which the reduction reaction occurs is the cathode and is at a negative voltage. 

The electrode alone is not sufficient for a redox reaction to take place, since a redox reaction involves the interaction of more than a single component. The other chemical components of the reaction are contained in the electrolyte. For many practical battery systems, the electrolyte is an aqueous solution. One reasons for having an aqueous solution is the oxidized or reduced form of the electrode exists in an aqueous solution. Further, it is important that the chemical species in the electrolyte be mobile in order that they can move to the site on the electrode where the chemical reaction takes places, and also such that ion species can travel from one electrode to the other. 

The current in the battery arises from the transfer of electrons from one electrode to the other. During discharging, the oxidation reaction at the anode generates electrons and reduction reaction at the cathode uses these electrons, and therefore during discharging, electrons flow from the anode to the cathode. The electrons generated or used in the redox reaction can easily be transported between the electrodes via a conventional electrical connection, such as a wire attached to the anode and cathode. However, unlike a conventional electrical circuit, electrons are not the only charge carrier in the circuit. Electrons travel from the anode to the cathode, but do not return from the cathode to the anode. Instead, electrical neutrality is maintained by the movement of ions in the electrolyte. If each redox reaction has a different electrolyte, a salt bridge joins the two electrolyte solutions. The direction of the ion movement acts to prevent a charge build-up at either the anode or the cathode. In most practical battery systems, the same electrolyte is used for both the anode and the cathode, and ion transport can take place via the electrolyte itself, eliminating the need for a salt bridge. However, in this case a separator is also inserted between the anode and the cathode. The separator prevents the anode and cathode from physically touching each other since they are usually in very close physical proximity to one another, and if they were to touch it would short out the battery as the electrons can be transferred directly without flowing through the external circuit and load.

The redox reactions which comprise a particular battery system define many fundamental parameters about the battery system. Other key battery properties, including as battery capacity, charging/discharging performance and other practical considerations are also influenced by the physical configuration of the battery, for example the amount of material in the battery or the geometry of the electrodes. The following pages describe how battery characteristics – voltage behavior, battery efficiency, battery non-idealities (self-discharge, degradation of battery capacity, etc) – are dependent on the operation of the redox reactions and the battery configuration.

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The Chemistry of Batteries

  • 🗔 April 28, 2022
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The Chemistry of Batteries

Batteries consist of multiple voltaic cells or one cell connected to form a unit. This unit is called a battery. Each battery contains two metal plates and a chemical that consists of positive and negative ions. The two metal plates form the electrode, and the chemical present in the battery is the electrolyte. A battery converts the chemical energy inside the cell into electrical energy, which helps us power electronic devices. It provides electricity to laptops, mobile phones and even clocks. To understand the chemistry of Batteries further, we will first study the two main types of batteries – 

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Table of Contents

Primary Battery

A type of battery in which the chemical reaction occurs only once. This property limits primary batteries to recharge like other batteries. Flashlights, remote controls, televisions, and smoke detectors use primary batteries. The most common example of a primary battery is the dry cell called the Leclanche cell (Zinc-carbon battery).

Working of primary batteries | Chemistry of Batteries

  • Zinc-carbon battery.

There are two components of zinc-carbon batteries: the zinc shell and the carbon rod. It is the first mass-produced battery used as a source of electric supply in appliances.

The zinc shell acts as the anode and functions as a container. And the carbon rod acts as the cathode, surrounded by a layer of powdered manganese dioxide. The space between the cathode and anode consists of ammonium chloride(NH4CL) and zinc chloride(ZnCl2).

The zinc atoms oxidize on the anode and combine with the ammonium ions to form ZNNH304, while manganese dioxide undergoes reduction on the cathode. 

assignment of batteries

Zn(s) → Zn 2+ (aq) + 2e –

2e – + 2NH 4+ (aq) → 2NH 3 (g) + H 2 (g)

Overall reaction: 

Zn(s) + 2NH 4 +(aq) + 2MnO 2 (s) → [ Zn(NH3) 2 ] 2 +(aq) + Mn 2 O 3 (s) + H 2 0(l)

Because these are oxidation-reduction reactions that occur, they are called half-reactions. The reaction which takes place in the zinc-carbon dry cell produces 1.5V.

The zinc-carbon battery is used in appliances that require low to medium electric supply. 

  • Alkaline Battery

Alkaline batteries use zinc at the anode and manganese dioxide at the cathode. The battery uses an alkaline chemical called potassium hydroxide. In the alkaline battery oxidation-reduction reaction, the zinc at the anode releases electrons to form Zinc oxide. These electrons get transferred to the cathode. Hence, manganese dioxide gets reduced. 

assignment of batteries

Zn(s) + 2OH – (aq) → ZnO(s) +H 2 O(l) + 2e –

2MnO 2 (s) + H2O(l) + 2e – → Mn 2 O 3 (s) + 2OH – (aq) 

Zn(s) + 2MnO 2 (s) → ZnO(s) + MnO 3 (s)

Alkaline batteries have a longer shelf life than the Leclanche batteries, but they provide the same voltage of 1.5V.

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Secondary Battery:

In secondary batteries, the chemical reaction can be reversed and hence these batteries are rechargeable. The electrons discharged in these cells get restored, which helps the batteries recharge again once connected to the electric source. A secondary cell or battery is heavy and complex among all types of batteries. But it is still used in inverters and car batteries due to its cost-efficiency. 

Working of secondary batteries

  •  Nickel-cadmium battery

As the name suggests, this battery contains nickel at the cathode and cadmium at the anode. The potassium hydroxide acts as the electrode in nickel-cadmium batteries. While charging, the nickel hydroxide present at the cathode forms nickel oxyhydroxide. And at the anode, cadmium hydroxide is formed from cadmium. 

assignment of batteries

Cd(s) + 2OH – (aq) → Cd(OH) 2 (s) + 2e –

2NiO(OH)(s) + 2H2O(l) + 2e – → 2Ni(OH) 2 (s) + 2OH – (aq)

Overall reaction:

Cd(s) + 2 NiO(OH)(s) + 2H2O(l) → 2Ni(OH) 2 (s) + Cd(OH) 2 (s)

This battery gives a better performance than other alkaline batteries due to its jelly roll design. The overall voltage from the nickel-cadmium battery ranges from 1.2V to 1.25V. Nickel-cadmium batteries are present in computers and radio components.

  • Lithium-ion batteries

While charging, the lithium ions in the batteries get transferred from anode to cathode. The movement of electrons gets reversed when the battery connects to a device. The lithium ions get released from the cathode to the anode. A separator in the lithium-ion battery functions as a block to the free flow of electrons.

Li(s) → Li + + e –

Li + + CoO 2 + e – → LicoO 2 (s)

Li(s) + CoO 2 → LiCoO 2 (s)

Lithium-ion batteries produce around 3.7V. They are present in cameras and tablets. Recently, lithium-ion batteries-are installed in electric cars on a large scale.

Batteries consist of voltaic cells that help in charging a device. Devices that use them include medical devices, vehicles, remote controls and submarines. Electric cars use lithium-ion and lead-acid batteries on a large scale. On the other hand, primary batteries are used- in household appliances. They are non-rechargeable and have an efficiency of less than 2%- due to which secondary batteries are preferable. 

Secondary batteries have a high power density and a high discharge rate in comparison to primary batteries. They can be used, at low temperatures, unlike primary batteries. The initial cost of setting up a secondary battery is high, but it has efficient performance outputs. 

The future use of cells and batteries is rising. Fuel cells use fuel in place of other chemicals in the electrochemical cell. This method is currently three times more efficient than the other methods. 

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FAQS (Frequently Asked Questions)

  • Which batteries cannot recharge?

Primary batteries cannot recharge once used because the chemical reaction in primary batteries is not reversible. Primary batteries are present in household appliances like TV, radio, remote control and other electronic devices.

  • What are the two types of batteries?

Primary and secondary batteries. Primary batteries are not rechargeable and have low efficiency. Secondary batteries are rechargeable. And are used as car batteries and also in electric vehicles.

  • Why are secondary batteries better than primary batteries?

Secondary batteries have higher efficiency and recharge when connected to an electric supply. Most used secondary batteries and lithium-ion and nickel-cadmium batteries. Lithium-ion batteries work on jelly-rod designs. 

  • What are the chemicals used in batteries?

Chemicals such as zinc chloride, sodium chloride, potassium nitrate and magnesium hydroxide are present in electrochemical cells or batteries. These chemicals function as electrolytes in the batteries.

[1] Electrochemical Power Sources: Primary and Secondary Batteries , edited by M. Barak

[2] Introduction:  Batteries and Fuel Cells , M. Stanley Whittingham Robert F. Savinell and Thomas Zawodzinski

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    1 Introduction. Energy storage is essential to the rapid decarbonization of the electric grid and transportation sector. [1, 2] Batteries are likely to play an important role in satisfying the need for short-term electricity storage on the grid and enabling electric vehicles (EVs) to store and use energy on-demand. []However, critical material use and upstream environmental impacts from ...

  13. Batteries: Meaning, Types, Size, Importance, and Shapes

    A battery is a device made up of various voltaic cells. Each voltaic cell is made up of two half cells linked together in series by a conductive electrolyte containing anions and cations. The electrolyte and the electrode to which anions move, i.e., the anode or negative electrode, are in one half of the cell; the electrolyte and the electrode ...

  14. Battery Voltage

    We recommend using the latest version of Chrome, Firefox, Safari, or Edge. Look inside a battery to see how it works. Select the battery voltage and little stick figures move charges from one end of the battery to the other. A voltmeter tells you the resulting battery voltage.


    • Lithium-sulfur batteries have a cathode made of a sulfur-based compound and an anode made of lithium. These batteries have a higher energy density than lithium-ion batteries, and are 18 For more information on the history of lithium-ion batteries, read Seth Fletcher's book Bottled Lightning: Superbatteries, Electric Cars, and the

  16. Assignment PDU

    ASSIGNMENT PDU TOPIC: 1. TYPES OF BATTERIES 2. FURNACES AND WELDING METHODS BATTERIES: A battery is a device that produces electrons through electrochemical reactions, and contains positive (+) and negative (-) terminals. A battery consists of one or more electrochemical cells, which transform stored chemical energy directly into electrical energy.

  17. PDF Module 2: Battery, Charging, Electrical Systems

    Stop Start Technology. Engine shuts off at stops. Sometimes may not be obvious. Maybe important to know if working on car with a disabled start/stop function. Auto start stop icon on dash cluster Aux. battery in trunk. Battery switch module on battery Rpo codes (GM LK9) Disable button (not on GM) NOT by starter visual inspection.

  18. Understanding the impedance spectra of all-solid-state lithium battery

    1. Introduction. The all-solid-state battery (ASSB) that uses a solid lithium ion conductor as the electrolyte, instead of a liquid electrolyte as in current lithium batteries, is a promising configuration for next-generation lithium batteries [1].ASSBs can widen the range of operation temperature at high power density when employing solid electrolytes (SEs) with high thermal stability, high ...

  19. Conclusion

    If you want to take your project portable you'll need a battery pack! For beginners, we suggest alkaline batteries, such as the venerable AA or 9V cell, great for making into larger multi-battery packs, easy to find and carry plenty of charge. If you want to go rechargeable to save money and avoid waste, NiMH batteries can often replace alkalines. Eventually, however, you may want to upgrade ...

  20. The Chemistry of Batteries

    The Chemistry of Batteries. Batteries consist of multiple voltaic cells or one cell connected to form a unit. This unit is called a battery. Each battery contains two metal plates and a chemical that consists of positive and negative ions. The two metal plates form the electrode, and the chemical present in the battery is the electrolyte.

  21. Sodium ion batteries: Assignment of a dedicated UN number and ...

    Sodium ion batteries: Assignment of a dedicated UN number and related special provisions - corrections to document ST/SG/AC.10/C.3/2021/55 (France)

  22. Finding probability on operation time of batteries

    The probability assignment is assumed to be. P(A) = ∫A 1 λe−x/λdx P ( A) = ∫ A 1 λ e − x / λ d x. for any event A ⊆ [0, ∞) A ⊆ [ 0, ∞), where λ > 0 λ > 0 is a known constant. Thus the probability that a battery fails after time t t is given by. P(t, ∞) = ∫∞ t 1 λe−x/λdx, t ≥ 0. P ( t, ∞) = ∫ t ∞ 1 λ e ...

  23. Sodium-ion batteries: Assignment of a dedicated UN number and ...

    Sodium-ion batteries: Assignment of a dedicated UN number and related special provisions - Follow-up on document ST/SG/AC.10/C.3/2020/45/Rev.1 (France)