Electric Battery: Types and Mechanisms

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【Summary】Electric batteries are essential for portable electric power and have revolutionized convenience and sustainability. The roots of batteries can be traced back to Luigi Galvani's experiment in 1780, followed by Alessandro Volta's voltaic pile and Michael Faraday's discoveries. Batteries consist of two half-cells with metal electrodes immersed in electrolytes, connected by a wire and salt bridge. The cathode is the positively charged electrode, while the anode is the negatively charged electrode.

FutureCar Staff    Nov 14, 2023 5:16 AM PT
Electric Battery: Types and Mechanisms

Electric batteries have revolutionized our lives by increasing the penetration of motorization and wirelessness. These batteries store and release electrical energy that they have acquired by converting other forms of energy, particularly chemical energy. They serve as portable sources of electric power and are at the foundation of convenience in industrialized societies. Innovations to improve their efficiency will shape the future of convenience and sustainability.

The roots of electric batteries can be traced back to Luigi Galvani's experiment in 1780. Galvani discovered that when he touched two plates of different metals to a frog's leg, the leg contracted. However, he couldn't explain why this happened. Alessandro Volta built on Galvani's work and created the voltaic pile in 1800, which consisted of copper and zinc plates separated by sheets of paper soaked in salty water. Volta found that this set-up could produce a steady current but couldn't explain why. It was Michael Faraday in the early 19th century who finally explained how these cells worked and named their various components.

An electric battery is a collection of cells. A cell, such as a voltaic or galvanic cell, uses redox reactions to produce an electric current. It consists of two half-cells, each made of a metal electrode immersed in an electrolyte of that metal. The two electrodes are connected by a wire, and the two electrolytes are connected by a salt bridge. In the cell, zinc ions from the zinc electrode dissolve in the zinc sulphate and release electrons, while copper ions from the copper sulphate deposit onto the copper electrode and require electrons. The wire and the salt bridge facilitate the transfer of electrons and ions between the electrodes and electrolytes, allowing the flow of electric current.

Within a battery, the cathode is the positively charged electrode where electrons arrive, while the anode is the negatively charged electrode that supplies electrons. The energy imparted to the electrons by the half-cells is called the source voltage, which is equal to the terminal voltage in ideal conditions. The higher the source voltage, the greater the cell's electrochemical potential. However, corrosion can degrade the performance of electrochemical cells. Factors such as water droplets condensing on the electrodes or galvanic corrosion can lead to electrode corrosion.

There are various types of batteries, including the widely known lithium-ion (Li-ion) battery and the batteries used in electric vehicles (EVs). Li-ion batteries are rechargeable and have had a revolutionary impact on the 20th and 21st centuries. They consist of a lithium metal oxide cathode, a graphite anode, and a semisolid polymer gel electrolyte. The voltaic phase involves lithium oxidizing in the anode and releasing an electron, while the electrolytic phase charges the cell by moving lithium ions from the graphite to intercalate in the metal oxide. Li-ion batteries are extensively researched, resulting in different configurations and pros and cons.

Li-ion batteries also power EVs, such as Tesla's Model S cars, which use the P85 battery consisting of 18,650 Li-ion cells. Additionally, fuel cells, particularly hydrogen fuel cells, are another source of electric power in motor vehicles. Hydrogen fuel cells separate hydrogen into protons and electrons at the anode, with the electrons flowing through an external circuit and the protons through the electrolyte to the cathode. At the cathode, the particles react with oxygen to create heat and water. Fuel cells are expected to play a crucial role in the hydrogen economy, with the Indian government recently approving the National Green Hydrogen Mission to utilize and export green hydrogen.

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