Lithium ion battery electrolyte, short for electrolyte, is a key material of lithium ion battery and plays an important role in cycle life, safety and capacity play. Electrolyte is mainly made from electrolyte lithium salts, solvents and additives. Electrolyte lithium salts are key component of electrolyte and existence of which ensure there are enough lithium ions come and go between positive pole and negative pole in charging/discharging cyclic process. Electrolyte lithium salts have requirements as below:
1) Well soluble to organic solvents, easy to be dissociated to ensure electrolyte has good conductivity;
2) Has quite good electrochemical stability and chemical stability;
3) Environment friendly, cleavage product influence to environment is small;
4) Easy to prepare and purify and price is quite cheap.
Comprehensive each requirement, currently, the most widely used electrolyte salt is LiPF6. Although it already has quite good comprehensive performances, as its instability, easy to absorb water, low life and poor low temperature performance etc. its self disadvantages, it could not meet LIB’s special application requirements.
Developing new electrolyte lithium salts to partly replace mainstream LiPF6 products, increasing battery high temperature stability, reducing HF generation and increasing capacity retention rate after high temperature preservation is one of electrolyte performance optimization directions in recent years. Currently, in market, there are some new electrolyte lithium salts put into application, include LiBOB, LiODFB, LiFSI and LiTFSI etc. Part enterprises’ new electrolyte lithium salts projects are as below:
Capchem
In Jul, 2016, Shenzhen Capchem released announcement that, the company planned to joint establish Hunan Bofu New Material Technology Co. Ltd. with Changsha Xinlianhua New Energy Ltd. Partnership, and take this company as project implementation executer to construct 200t/a LiFSI project in Chenzhou, Hunan. Capchem 2016 Annual Report shows that, this LiFSI project started to trial run at the end of 2016 and part technologies are still under further optimization and adjustment.
Tinci Materials
Tinci Materials 2016 Annual Report shows that, the company 300t/a LiFSI production line project entered closeout phase.
In May 2016, Jiujiang Tianqi Fluorine Silicon New Material Technology, wholly owned subsidiary of Jiujiang Tinci, wholly owned subsidiary of Tinci Materials, 2300t/a new type lithium salts project EIA 2nd time publicity. The project locates in Jiujiang, Jiangxi, planned to invest CNY 202M to construct 2000t/a LiFSI, 150t/a LiPF2 and 150t/a LiTDI. Currently, the project is still under construction.
Yongtai Technology
In Jul 2016, Yongtai Technology released announcement, Shaowu Yongtai Advanced Material Co. Ltd., holding subsidiary of the company, planned to use self capital CNY 387.6M to construct 2000t/a LiFSI projects etc. Among, Phase-1 will form 1000t/a LiFSI production capacity and construction period is estimated to be one year and a half. News reported in Mar 2017, the project planned to enter test production in May.
Suzhou Fluolyte
In Jun 2015, the company 1000t/a LiFSI project started construction. Suzhou Fluolyte 2016 Annual Report shows that, Phase-1 of this project is under construction.
Jiangsu Guotai
Jiangsu Guotai 2015 Annual Report shows that, development of the company LiFSI system electrolyte pilot test completed; LiTFSI industrialization research and application development project has realized batch production, and would base on 30t/a device to implement 200t/a LiTFSI industrialization project, optimize relevant technologies and further increase target product’s technology level.
Nantong Hehui New Energy Material Co. Ltd.
In Oct 2015, Nantong Environment Protection Bureau approved and publicized Nantong Hehui New Energy Material Co. Ltd. 310t/a LiBOB, 90t/a LiODFB etc. new type electrolyte lithium salts projects EIA book. However, currently, there is no other information on this project.
Except continuous R&D new type lithium salts, improve current products performance and preparation technologies, combine different performance, different structure’s electrolyte lithium salts and make them show excellent performances which some simple electrolyte lithium salts do not have also becomes electrolyte enterprises research’s key point. For example, in current LiFSI’s practical application, it is more common to mix use with LiPF6.
Electrolyte lithium salts play important roles in performances of electrolyte and LIB. LiPF6 becomes currently mainly electrolyte lithium salts because of many of its advantages. With increase of LIB industry requirement, some new type lithium salts show good development potential. However, as these new type lithium salts have limitation on cost etc. aspects, ASIACHEM believes that, in short term, LiPF6 will still be mainstream electrolyte lithium salts using in the industry. In long term, with continue improving of technology and gradually releasing of China enterprises new type electrolyte lithium salts capacity, these new type electrolyte lithium salts’ production cost will gradually decrease, new type electrolyte lithium salts’ market prospect is worth expecting.
