Interface Engineering via Regulating Electrolyte for High‐Voltage Layered Oxide Cathodes‐Based Li‐Ion Batteries

Abstract

Abstract Li‐rich and Ni‐rich layered oxides as next‐generation high‐energy cathodes for lithium‐ion batteries (LIBs) possess the catalytic surface, which leads to intensive interfacial reactions, transition metal ion dissolution, gas generation, and ultimately hinders their applications at 4.7 V. Here, robust inorganic/organic/inorganic‐rich architecture cathode‐electrolyte interphase (CEI) and inorganic/organic‐rich architecture anode‐electrolyte interphase (AEI) with F‐, B‐, and P‐rich inorganic components through modulating the frontier molecular orbital energy levels of lithium salts are constructed. A ternary fluorinated lithium salts electrolyte (TLE) is formulated by mixing 0.5 m lithium difluoro(oxalato)borate, 0.2 m lithium difluorophosphate with 0.3 m lithium hexafluorophosphate. The obtained robust interphase effectively suppresses the adverse electrolyte oxidation and transition metal dissolution, significantly reduces the chemical attacks to AEI. Li‐rich Li1.2Mn0.58Ni0.08Co0.14O2 and Ni‐rich LiNi0.8Co0.1Mn0.1O2 in TLE exhibit high‐capacity retention of 83.3% after 200 cycles and 83.3% after 1000 cycles under 4.7 V, respectively. Moreover, TLE also shows excellent performances at 45 °C, demonstrating this inorganic rich interface successfully inhibits the more aggressive interface chemistry at high voltage and high temperature. This work suggests that the composition and structure of the electrode interface can be regulated by modulating the frontier molecular orbital energy levels of electrolyte components, so as to ensure the required performance of LIBs.

Keywords

• graphite anodes
• high‐voltage electrolytes
• interface engineering
• Li‐rich/Ni‐rich cathodes
• lithium‐ion batteries