What are the properties of lithium ion battery electrolyte?

Lithium ion batteries electrolyte is soluble in organic solvents have electrolyte of lithium ionic conductor. Generally as a practical lithium ion battery organic electrolyte should possess the following properties:

(1) high ionic conductivity, general should reach 10-3 ~ 2 * 10-3 s/cm;Lithium ion transference number can approximate to 1;

(2) the electrochemical stability of the wide range of potential;There must be 0 ~ 5 v electrochemical stability window;

(3) good thermal stability, the use of wide temperature range;

(4) chemical performance is stable, with collection of fluid inside the cells and active substance does not react;

(5) safety low toxicity, best able to biodegradation.

Suitable solvent to its high dielectric constant, low viscosity, with alkyl carbonate in common use such as PC, EC, such as strong polarity, high dielectric constant, but the viscosity, molecular inter-atomic forces, in which lithium ions move slowly.Linear ester, such as DMC (dimethyl carbonate), DEC (diethyl carbonate) such as low viscosity, dielectric constant is low, therefore, in order to obtain high ionic conductivity of the solution, generally USES the PC + DEC, EC + DMC such as mixed solvent.The organic solvent has some smell, but in general, is to meet the eu RoHS, REACH requirements, is little toxic, environmental protection has a temper of the material.

The current development of inorganic anion conductive salt mainly LiBF4, LiPF6, LiAsF6 three categories, their electrical conductivity, thermal stability and oxidation resistance are as follows:

Electrical conductivity: LiAsF6 acuity LiPF6 > LiBF4

Thermal stability: LiAsF6 > LiBF4 > LiPF6

The oxidation resistance: LiAsF6 LiPF6 LiBF4 or higher or more

LiAsF6 have very high electrical conductivity, stability, and the battery discharge rate, but as a result of arsenic toxicity limit its application, is currently the most commonly used LiPF6.

The page contains the contents of the machine translation.