Electrochemical energy storage includes ().

Electrochemical energy storage mainly includes supercapacitors, lithium ion batteries and fuel cells.

Electrochemical energy storage is essentially to store electrical energy into chemical energy, and then release it through the mechanism of chemical batteries, put it into the power grid, and then change it back into electrical energy. Electrochemical energy storage includes lithium ion, sodium ion and liquid flow, among which lithium ion is the most mature, and sodium ion and liquid flow have yet to be developed.

Supercapacitor is a new type of energy storage device between traditional capacitor and rechargeable battery, and its capacity can reach hundreds to thousands of farads. Compared with traditional capacitors, it has larger capacity, specific energy or capacity density, wider working temperature range and longer service life. Compared with the battery, it has higher specific power and no pollution to the environment.

Compared with pumped storage, the biggest advantage of electrochemistry lies in its flexibility. It can build small energy storage stations around small enterprises or families, or at the level of large factories and power stations, such as wind power stations near the coast or photovoltaic power stations in the desert.

The most commercial potential of electrochemical energy storage is lithium ion battery. Lithium batteries have been developed for many years. With the popularization of electric vehicles, both technical maturity and cost have reached the level of mass production of several hundred GW/h per year, which has reduced the cost of energy storage batteries from 3 yuan to 1.5 yuan.

Fuel cell is a chemical device that directly converts the chemical energy of fuel into electrical energy, also known as electrochemical generator. It is the fourth power generation technology after hydropower generation, thermal power generation and atomic power generation.

Because the fuel cell partially converts Gibbs free energy in fuel chemical energy into electric energy through electrochemical reaction, it is not limited by Carnot cycle effect, so it has high efficiency.

In addition, the fuel cell uses fuel and oxygen as raw materials, and has no mechanical transmission parts, so it has less harmful gas emission and long service life. Therefore, from the point of view of energy saving and ecological environment protection, fuel cell is the most promising power generation technology.