An electrolyte to improve the deep charge-discharge performance of LiNi0.8Co0.15Al0.05O2 cathode

作者：Zhou, Hongming; Yang, Zhaohui; Xiao, Demin; Xiao, Kaiwen; Li, Jian^*

来源：Journal of Materials Science: Materials in Electronics , 2018, 29(8): 6648-6659.

DOI：10.1007/s10854-018-8650-y

• LITHIUM DIFLUORO(OXALATO)BORATE LIDFOB
• HIGH-VOLTAGE
• ELECTROCHEMICAL PERFORMANCES
• LINI0.5MN1.5O4 CATHODE
• ION BATTERIES
• CARBONATE
• SALT
• SULFONE
• TRIS(TRIMETHYLSILYL)PHOSPHATE
• SOLVATION

The electrochemical behaviors of electrolytes, 1 M lithium difluoro(oxalate)borate (LiODFB) in sulfone and dimethyl carbonate blends, have been investigated for LiNi0.8Co0.15Al0.05O2 (NCA) cathode. The viscosity and conductivity tests have been used to investigate the relationship among the solution viscosity, conductivity and electrolyte composition. Through linear sweep voltammetry, cyclic voltammetry, AC impedance and charge-discharge test, we have compared the electrochemical stability of different electrolytes, the reversibility, capacity, cycling performance, rate capability and interfacial impedance of NCA cathode in different electrolytes. SEM, XPS, TEM and FTIR analyses have utilized to discuss the surface nature of NCA cathode after cycles at deep charge-discharge voltage. These results demonstrate that 1 M LiODFB/(SL-DMC, 4:6) electrolyte shows the maximum conductivity value (kappa(max) = 4.25 S cm(-1)), proper viscosity (eta = 3.43 mPa s) and high oxidative decomposition potential (5.66 V) and NCA cathode can present superior reversibility, higher columbic efficiency during cycles in this electrolyte than in 1 M LiPF6/(EC-DMC, 3:7) electrolyte. Besides, a dense deposition layer is formed on the NCA cathode when NCA/Li cells cycle in 1 M LiODFB/(SL-DMC, 4:6) electrolyte with deep charging and discharging process, which can avoid the erosion of electrolyte to transition-metal elements, restrain the damage of NCA structure, and then improves the cycle performance of NCA/Li cells.

• 出版日期2018-4
• 单位中南大学