A flexible [(DMPI+)(AlCl4−)]/PVDF-HFP polymer gel electrolyte and its electrochemical performance for dual-graphite batteries

Abstract

Recently, dual-graphite batteries (DGBs) receive growing attention for their advantages of high working voltage, environmental friendliness and inexpensive. However, the conventional liquid organic electrolytes used in DGBs still possess issues of safety and electrolyte leakage that might limit their further development. Herein, a non-flammable [(DMPI+)(AlCl4−)] ionic liquid (DAIL) is embedded into a polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) matrix to prepare a [(DMPI+)(AlCl4−)] polymer gel electrolyte (DAPGE) for solving these conventional issues. The DAPGE, as both the electrolyte and separator, is characterized and electrochemically tested in DGB, which shows favourable ionic conductivity of 2.28 × 10−3 S cm−1. The DGB using a DAPGE shows a specific capacity of 80 mAh g−1 at a current density of 100 mA g−1. Moreover, the DGB pouch cell with DAPGE can work well under bending, critical temperature and even exposure to air. Besides, DAPGE decreases the utilization (around 40%) of liquid IL electrolyte as compared to that of conventional glass fibre separators does. Consequently, the application of DAPGE in DGBs shows promise for achieving higher energy density and better robustness.