Liquid lithium batteries are mainly composed of four parts: positive electrode material, negative electrode material, separator, and electrolyte. The electrolyte is mainly responsible for conducting conductive ions between the positive and negative electrodes. It plays a key role in the battery's energy density, cycle life, power density, safety performance, and wide-temperature application, and is known as the "blood of the battery".
In battery applications, electrolytes need to meet performance requirements such as high conductivity, good thermal stability, high chemical stability, wide electrochemical window, wide operating temperature range, and good safety. So, what are the main components of lithium-ion battery electrolytes?
The main components of lithium battery electrolyte are solvents, solutes, and additives, which are formulated in proportions under certain conditions. The mass percentages of the three raw materials are 80%-85%, 10%-12%, and 3%-5%, respectively, and their cost percentages are 25%-30%, 40%-50%, and 10%-30%, respectively.
1. Solvents: Primarily used as transport carriers for lithium ions, commonly used solvents are carbonates, including propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (EMC). In practice, a mixture of high and low viscosity solvents is generally used, with common combinations being EC+DEC, EC+DMC, EC+DMC+EMC, and EC+DMC+DEC.
2. Solute: As the provider of lithium ions, lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), and novel lithium salt lithium difluorosulfonylimide (LiFSI) are generally selected.
3. Additives: Substances with specific functions. Electrolytes generally contain a variety of additives, which are classified according to their function as film-forming additives, high/low temperature additives, overcharge protection additives, flame retardant additives, rate-dependent additives, etc. Common additives include vinylene carbonate (VC) and fluoroethylene carbonate (FEC).
