Three major categories of electrochemical energy storage

This chapter describes the basic principles of electrochemical energy storage and discusses three important types of system: rechargeable batteries, fuel cells and flow batteries. A rechargeable battery consists of one or more electrochemical cells in series.

Electrochemical energy storage systems are the most traditional of all energy storage devices for power generation, they are based on storing chemical energy that is converted to electrical energy when needed. EES systems can be classified into three categories: Batteries, Electrochemical capacitors and fuel Cells.

The most common chemical energy storage systems include hydrogen, synthetic natural gas, and solar fuel storage. Hydrogen fuel energy is a clean and abundant renewable fuel that is safe to use. The hydrogen energy can be produced from electrolysis or sunlight through photocatalytic water splitting (16,17).

These classifications lead to the division of energy storage into five main types: i) mechanical energy storage, ii) chemical energy storage, iii) electrochemical energy storage, iv) electrostatic and electromagnetic energy storage, and v) thermal energy storage, as illustrated in (Figure 2).

Electrostatic and electromagnetic energy storage systems store electrical energy, with no conversion to other forms of energy (i.e., stores as electric field). Capacitors, Supercapacitors and Superconducting magnetic Energy Storage (SMES) belong to this type of energy storage system (32).

It was classified into three types, such as sensible heat, latent heat and thermochemical heat storage system (absorption and adsorption system) (65). (Figure 14) shows the schematic representation of each thermal energy storage systems (66). Figure 14. Schematic representation of types of thermal energy storage system. Adapted from reference (66).