Stabilizing the cycling stability of rechargeable lithium metal batteries with tris(hexafluoroisopropyl)phosphate additive  

三(六氟异丙基)磷酸酯添加剂稳定可充电锂金属电池的循环稳定性

作　　者：Huaihu Sun Jiandong Liu Jian He Huaping Wang Gaoxue Jiang Shihan Qi Jianmin Ma 孙怀虎;刘建东;何健;王华平;姜高学;戚世瀚;马建民(School of Physics and Electronics,Hunan University,Changsha 410082,China;School of Materials and Energy,University of Electronic Science and Technology of China,Chengdu 611731,China)

机构地区：[1]School of Physics and Electronics,Hunan University,Changsha 410082,China [2]School of Materials and Energy,University of Electronic Science and Technology of China,Chengdu 611731,China

出　　处：《Science Bulletin》2022年第7期725-732,共8页科学通报（英文版）

基　　金：the National Natural Science Foundation of China(51971090 and U21A20311)。

摘　　要：The application of rechargeable lithium metal batteries(LMBs)has been hindered by the fast growth of lithium dendrites during charge and the limited cycling life because of the decomposition of the electrolyte at the interface.Here,we have developed a non-flammable triethyl phosphate(TEP)-based electrolyte with tris(hexafluoroisopropyl)phosphate(THFP)as an additive.The polar nature of the C–F bonding and the rich CF3 groups in THFP lowers its LUMO energy and HOMO energy to help form a stable,Li F-rich solid electrolyte interphase(SEI)layer through the reduction of THFP and increases the binding ability of the PF6-anions,which significantly suppresses lithium dendrite growth and reduces the electrolyte decomposition.Moreover,THFP participates in the formation of a thin,C–F rich electrolyte interphase(CEI)layer to provide the stable cycling of the cathode at a high voltage.The symmetric Li||Li and full Li/NCM622 cells with THFP additive have small polarization and long cycling life,which demonstrates the importance of the additive to the application of the LMBs.由于锂枝晶在充电过程中的快速生长以及界面电解液的分解导致电池循环寿命有限,阻碍了可充电金属锂电池的应用.本文开发了一种以三(六氟异丙基)磷酸酯(THFP)为添加剂的不燃磷酸三乙酯(TEP)基电解液. THFP中C-F键的极性和丰富的CF3基团降低了其LUMO能量和HOMO能量,通过THFP的还原分解来帮助形成稳定的、富含Li F的负极电解质界面膜,同时增加了THFP和PF6-阴离子的结合能力,显著抑制了锂树枝晶生长并减少了电解质分解.此外, THFP参与形成薄的、富含碳氟的正极电解质界面膜,可以在高压下提供阴极的稳定循环.含有THFP添加剂的对称Li||Li和Li/NCM622全电池具有较小的极化和较长的循环寿命,这表明添加剂对锂金属电池的应用具有重要性.

关 键 词：Lithium metal batteries Electrolytes Non-flammable electrolytes Lithium dendrites Solid state interphase 

分 类 号：TQ225.24[化学工程—有机化工] TM912[电气工程—电力电子与电力传动]