How to improve the low temperature performance of lithium iron phosphate batteries?

　　1. Surface covering and lowering the surface resistance of LFP particles

　　At low temperature, the impedance of the electrode material interface will increase, and the ion diffusion rate will be reduced. Covering a layer of conductive layer on the LFP surface will effectively reduce the contact resistance between the electrode materials, thereby increasing the diffusion rate of ions entering and leaving the LFP.

　　The generally covered material is carbon material. For example, the use of non -fixed carbon or carbon nanotubes or graphene can be used to reduce the impedance of the LFP electrode material interface. The other is to coat with metal or metal oxide. Studies have shown that CEO2 particles can be evenly distributed on the LFP surface. At low temperature, the CEO2 improvement of post -LFP's decapyles/embedded capacity and electrode dynamics have been significantly improved.

　　2. The resistance of the body phase reduces the resistance of the LFP electrode

　　Ion doping can form a vacancy in the LFP crystal structure, thereby promoting the diffusion of lithium ions in the electrode material.

　　Studies have shown that the LFE0.92mg0.08 (PO4) 0.99F0.03 obtained by MG and F has good electrochemical properties at low temperatures. The doping of the two ions does not change the particle size and structure of the material, and also increases the ion conduction rate and electronic transfer rate.

　　3. Optimization of electrolyte

　　This may not only be applied to the LFP system, and the lithium battery of the three yuan or other organic electrolyte systems can be applied.

　　At low temperature, the transmission of lithium ions in the electrode/electrolyte interface is the control step of its performance. Increasing low temperature performance, the important point is to increase the rate of electrochemical reactions in the interface. Therefore, the optimization of the SEI membrane is very important, and the nature of the SEI membrane is determined by the electrolyte and the surface of the electrode. Therefore, optimization of electrolyte can also improve the low temperature performance of lithium batteries.

　　Studies have shown that the introduction of the solvent with long molecular chains or ester with a long molecular chain or higher molecular quality in the electrolyte can increase the stability of the SEI membrane, stabilize the lithium ion to stabilize, and reduce the polarization of the battery.

　　In addition, the selection of lithium salts in electrolytes also affects lithium ion conductivity and the stability of SEI membrane.

　　4. Optimization of charging strategy

　　Use pulse current to quickly heat the battery temperature at low temperature.

　　During the charging process, the ion movement and polarization in the electrolyte can promote the production of the internal heat of the lithium battery, which can effectively be used to improve its performance at low temperature.

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