Trinitarian Stabilization of Electrolyte/Interphase/Cathode for 5.0–5.4 V Dual‐Ion Batteries Realized by a Gel‐Polymer Electrolyte Capable of HF Elimination

Dual-ion batteries (DIBs) that are composed of graphite cathodes and low-potential anodes such as Li possess the unique advantages of high working voltage (≈5.0 V) and high power density, but suffer from the serious oxidative decomposition of electrolyte and cointercalation of solvent/anions into graphite cathode, leading to unsatisfactory cycling stability. From the perspectives of blocking the generation of corrosive HF in electrolyte and reinforcing the stability of cathode/electrolyte interphase (CEI), a gel-polymer electrolyte incorporating zeolite molecular sieve into the polymer matrix of polyvinylidene fluoride and polyacrylonitrile is prepared and utilized in DIBs. The physicochemical and electrochemical properties of this gel-polymer electrolyte are systematically studied and compared with those of liquid electrolytes. This gel-polymer electrolyte is demonstrated to be able to mitigate the oxidative decomposition of solvent at graphite cathode and inhibit the generation of HF that corrodes CEI. The stability of the CEI layer and graphite cathode during the long-term cycling is improved significantly. The assembled Li||graphite DIBs exhibit an outstanding capacity retention of 88.3% after 6000 cycles at 25 °C, and also allow stable cycling at 60 °C and a high cutoff voltage of 5.0-5.4 V.