The Research&Development Of Low Temperature Electrolyte In Lithium-Ion Power Battery

New energy car have put forward more and more strict electrochemistry performance requires toward Lithium ion battery such as charge/discharge efficiency, rates,safe performance and so on. Compare to traditional Lithium ion battery it need more wide useful temperature range. Especially at low temperature, traditional Lithiom ion battery is can’t meet the need.Electrolyte is the key part of the Lithium ion battery, it can affect the battery performance largely. Its main function is transport Li+and form SEI on anode. So, electrolyte need not only high ion conductivity but also the ability of forming thin and stable SEI on anode. Considering the run condition of the Lithium ion power battery, electrolyte still need have wide and stable electrochemistry voltage range and temperature range.The low temperature charge/discharge ability is the main short of the power Lithium ion battery, and improve the battery’s low temperature by electrolyte is all-important. The research main improve the low temperature refer to three aspect: optimize the composition of solvent, new additive and integration improvement.(1) The research of solvent system indicate:solvent have the different affect in conductivity, it can sort in the order base on the effect DMC>EC>EMC>DEC. Althogh vinegar ester such as EA can improve low temperature and rate effectually, but it reduce the long cycle and high temperature badly. Via the DOE experiment and the tests of conductivity,viscidity and the melt point, we find out the best solvent system is:EC/EMC/DMC=30/50/20(v/v/v).(2) The research of additives indicate:FEC’s SEI have low impedance characteristic at low temperature and may be the most suit for base additive; add the B1additive to the electrolyte, the low temperature can improve effectually; It will have excellent low temperature performance if use FEC and B1.(3) For improving the FEC+B1system’s bad high temperature,we have study many high temperature additives. The study indicate that the adding of MMDS base on FEC+B, the electrolyte’s high temperature and long cycle performance can improve largely, at the same, its low temperature performance still excellent.In conclusion, by optimizing the composition of solvents and the study of new additives and the integration improvement. We have develop a good power Lithium ion battery electrolyte, and the battery which use the electrolyte have excellent low temperature performance and good cycle and high temperature capability.