Optimization of Gel Polymer Electrolyte with different quaternary ammonium Cl salts for Chloride-ion battery

Chloride-ion batteries (CIBs) are auspicious energy storage materials because of their high theoretical volumetric energy density and facile availability of precursors with chlorine. The intrinsic cyclability, however, in traditional CIBs is low because of the dissolution of Cl-containing cathode materials in liquid electrolytes. Gel polymer electrolytes (GPEs) can solve the dissolution issue. In this study, effect of quaternary Cl salts on properties of PVDF-HFP-based GPEs and their compatibility with VCl₃ cathode are investigated. The Cl salts largely affect properties of GPEs. The highest ionic conductivity of 4.36 × 10⁻⁴ S cm⁻¹ is obtained in triethyl methyl ammonium chloride (TEMACl) containing-GPE. VCl₃ cathode is tested by using the developed GPE. The initial capacity is 66 mAh g⁻¹ and capacity retention is 25% at the 50th cycle, which exhibits reversible accommodation of Cl-ion in VCl₃ for the first time. This proves VCl₃ is a possible cathode material for rechargeable CIBs. The performance would be improved by reducing the particle size and compositing with carbonaceous materials.