In the current known low-temperature battery R & D and use, low-temperature lithium iron phosphate battery in the electrode materials, diaphragm, pole piece, pole ear shell and other aspects of the material is basically the same, to enhance the low-temperature performance of the same, the different, is a low-temperature electrolyte, the difference is relatively large, straight affects the battery in the low-temperature environment discharge performance, so enhance the performance of the low-temperature lithium iron phosphate battery from the electrolyte side of the immediate guest source Start.

The temperature range of lithium ion battery operation shows its use characteristics. At very low temperatures, aerospace requires lithium-ion batteries to have reasonable discharge efficiencies at -60°C to -80°C, while the drilling industry requires good performance at temperatures above 100°C.

In addition to these two market segments, most lithium-ion batteries are used in temperature windows of -50C to 80C. These windows include home electronics and power tools (-20C to 60C), HEVs (-30C to 70C) and usage (-50C to 80C).

Currently, most solvents for lithium-ion battery electrolytes are high-purity organic solvents from the carbonate series, such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC) and diethyl carbonate (DEC). However, a single solvent in the performance often can not have the actual requirements of the multi-faceted performance, will be a variety of solvents in a certain proportion of the multi-component mixture of solvents is often better than a single solvent. Improving the low-temperature performance of electrolytes by optimizing organic solvents means finding low melting point organic solvents that are miscible with current electrolytes.

Use the electrolyte solvent system with better thermal conductivity at low temperature to improve the body temperature of the battery when charging and discharging at low temperature, such as selecting the solvent system DMC+DEC.

Use organic solvents with lower melting point and viscosity to broaden the liquid temperature range of the electrolyte, such as the selection of carboxylic acid ester solvents ethyl propionate, methyl butyrate, etc.

Optimize the formulation:

ECIPCDMCEMCDEC, 2% VC + low temperature additives b) ECPCEMCEPDEC, 2% VC + low temperature additives

Currently the most widely used lithium salt is LiPF6, the main reason is that it has good solubility in organic solvents, relatively high conductivity, and relatively low cost. However, LiPF6 is very sensitive to trace water, and its analytical product contains HF, which is easy to corrode cathode materials and collector, and lacks temperature stability and affects the development of lithium-ion batteries. By using more stable lithium salt with better low temperature performance is also one of the key ways to improve the low temperature performance of electrolyte.

Adding additives to improve the low-temperature performance of organic electrolytes for lithium-ion batteries is another research hotspot, and is also an important development direction in this area in the future. Additives because of the small amount, quick results of the temple point, so in the basic does not increase the processing cost and change the processing technology, clearly improve the performance of lithium-ion batteries.