高纯六氟磷酸锂晶体产业化制备工艺研究进展

六氟磷酸锂(LiPF6)为三方晶系白色晶体，是锂离子电池电解液的关键材料. 近年来随着新能源汽车的高速发展，锂离子电池及相应电解质盐(LiPF6)需求快速增长. LiPF6易潮解、热稳定性差、腐蚀性强，合成中需采用多种有毒且强腐蚀性的原料，操作需在无水无氧环境下进行，涉及多步高低温处理过程，开发一种可工业化的高纯电子级晶体制备工艺具有重大意义. 目前已有多家国内企业开发了规模化制备工艺，但仍有很大改进和提升空间. 本工作综述了LiPF6的主要合成方法和国内主要生产企业的工艺开发进展，为未来LiPF6生产工艺升级改造提供参考和指导. 对锂离子电池的市场需求、电解质在锂离子电池中的作用、LiPF6规模制备工艺及最新LiPF6项目增产、投产状况进行了论述和分析.

Preparation process of high-quality LiPF6 crystals

Much more attentions are being devoted to high performance energy storage and conversion devices to conquer global warming issue and energy crisis. Lithium-ion battery, the most promsing device, is composed of anode, cathode, separator and electrolyte. Note should be highlighted that the performance of battery is determinded by electrolyte, espcially the safety issue. The demand of lithium-ion batteries and their electrolytes is growing rapidly with the rapid development of new energy vehicles recently. Lithium hexafluorophosphate (LiPF6) crystal is a white crystal with trigonal crystallographic structure. It is the key electrolyte material for Li-ion batteries. LiPF6 is combustible, corrosive and of poor thermal stability. Therefore, some toxic and corrosive precursors are employed, and their synthesis is required to be conducted within an anhydrous and anaerobic environment. Furthermore, many high temperature and low temperature treatments are involved in the synthetic procedure. Therefore, it is a huge challenge to produce high-purity LiPF6 crystals with an electronic grade in an industrial-scale. Fortunately, some industrial processes have been developed successfully by domestic enterprises even there is still some room for improving them. Here, the synthetic methods of LiPF6 and the domestic large-scale production processes are reviewed with the hope of providing some knowledge for future upgrade of the industrialized LiPF6 processes and a guideline for developing new synthetic routes. This review will concentrate on the development and intrinsic correlation among market demand of lithium-ion battery, role of electrolyte in lithium-ion battery, LiPF6 industrialized production procedures, and planned incremental capacity. In addition, the perspectives of potential electrolyte are summarized on basis of the progress of high-capacity and high-voltage electrode materials. There is no doubt that the future emphasis should be paid to the optimization of process, true demand of market, novel lithium salt, fluoridized solvents, and green techniques.