Electric Battery

An electric battery is essentially a source of DC electrical energy. It converts stored chemical energy into electrical energy through an electrochemical process. This then provides a source of electromotive force to enable currents to flow in electric and electronic circuits. A typical battery consists of one or more voltaic cells. 

The fundamental principle in an electrochemical cell is spontaneous redox reactions in two electrodes separated by an electrolyte, which is a substance that is ionic conductive and electrically insulated.

Chemical energy can be stored, for example, in Zn or Li, which are high-energy metals because they are not stabilized by d-electron bonding, unlike transition metals. Even though a wide range of types of batteries exists with different combinations of materials, all of them use the same principle of the oxidation-reduction reaction. Batteries are designed so that the energetically favorable redox reaction can occur only when electrons move through the external part of the circuit.

The voltage of electric batteries is created by the potential difference of the materials that compose the positive and negative electrodes in the electrochemical reaction. Because most of the resulting voltages are around 2V, cells are connected in series to obtain more practical electrical potentials (i.e. six 2V lead acid cells are connected in series to obtain a typical 12V battery).

Batteries are made of an extensive range of materials resulting in different capabilities and behaviors in the functionality of the battery. The most common ones are lead, nickel, and lithium, each of them with different outputs and specific for some different purposes depending on the requirements.

Chemistry of Electric Batteries

In simple terms, each battery is designed to keep the cathode and anode separated to prevent a reaction. The stored electrons will only flow when the circuit is closed. This happens when the battery is placed in a device and the device is turned on.

When the circuit is closed, the stronger attraction for the electrons by the cathode (e.g. manganese dioxide in alkaline batteries) will pull the electrons from the anode (e.g. zinc) through the wire in the circuit to the cathode electrode. This battery chemical reaction, this flow of electrons through the wire, is electricity.

If we go into detail, batteries convert chemical energy directly to electrical energy. Chemical energy can be stored, for example, in Zn or Li, which are high-energy metals because they are not stabilized by d-electron bonding, unlike transition metals.

Even though a wide range of types of batteries exists with different combinations of materials, all of them use the same principle of the oxidation-reduction reaction. In an electrochemical cell, spontaneous redox reactions take place in two electrodes separated by an electrolyte, which is a substance that is ionic conductive and electrically insulated. The redox reaction is a chemical reaction that produces a change in the oxidation states of the atoms involved. Electrons are transferred from one element to another. As a result, the donor element, which is the anode, is oxidized (loses electrons) and the receiver element, the cathode, is reduced (gains electrons).

For example, the Daniell cell consists of two electrodes of dissimilar metals, Zn and Cu; each electrode is in contact with a solution of its own ion; Zinc sulfate and copper sulfate respectively. The redox reaction that occurs in the Daniell Cell is:

These processes result in the accumulation of solid copper at the cathode and the corrosion of the zinc electrode into the solution as zinc cations. Excess electrons produced by the oxidation of zinc metal are “pushed” out of the anode, which is, therefore, the negative electrode, travel through the wire and are “pulled” into the copper cathode where they are consumed by the reduction of copper ions. The electrical current will cause a potential difference and an electromotive force. The spontaneous reaction will occur because zinc is a better reducing agent than copper and thereby more able to emit electrons. A stronger ability to emit electrons at the anode will cause a stronger electromotive force. A salt bridge or ion bridge, in electrochemistry, is a laboratory device used to connect the oxidation and reduction half-cells of a galvanic cell. It maintains electrical neutrality within the internal circuit.

Composition of Battery

Characteristics of Electric Batteries

To compare and understand the capability of each battery, some important parameters are characteristic of each battery, also within a type of battery. These parameters are a reference when a battery is needed, and specific qualities are required since batteries are used in all types of devices and for infinite purposes.

Types of Batteries

The following list is a summary of notable electric battery types composed of one or more electrochemical cells. Four lists are provided in the table. The first list is a battery classification by size and format. Then, the primary (non-rechargeable) and secondary (rechargeable) cell lists are lists of battery chemistry. The third list is a list of battery applications. The final list is a list of different battery voltages.