Safe propylene carbonate/water hybrid electrolyte for supercapacitor
Electrolyte is one of the most essential components for determining the safety, energy density, and cycling performance of the energy storage device, especially supercapacitors. Conventional high-concentration electrolytes have been widely used in high-performance energy storage devices due to their non-flammability and broad working voltage range. Nevertheless, almost all things have two sides, the low electrical conductivity and high viscosity of conventional high-concentration electrolytes commonly restrict the high rate performance of supercapacitors. Herein, propylene carbonate (PC) is introduced to conventional high-concentration electrolyte system to form a mixed electrolyte of "LiTFSI-PC/H2O". Compared to the conventional high-concentration electrolyte, this electrolyte has a significantly lower viscosity and higher conductivity without sacrificing. The supercapacitor assembled with 7 M LiTFSI-PC/H2O electrolyte remained at 15 F/g after cycling for 10,000 cycles at a current density of 1 A/g, and the Coulomb efficiency was still close to 100%. At the same time, this novel LiTFSI-PC/H2O hybrid electrolyte also reduces costs and improves safety.