Cotton Fiber/PVA-Based Neutral Hydrogel with Al<sup>3+</sup> as an Electrolyte Additive for High-Performance Supercapacitors
Zhixing Zhao, Yun Huang, He Zheng, Ling Zhao, Jiapin Liu, Chao Zou, Zhi Hui Dong, Xing Li, Mingshan Wang, Yuanhua Lin
Abstract
Electrolyte additives have been widely studied in the improvement of stability of aqueous electrolytes. Here, we report a crosslinking cotton fiber-/PVA-based membrane (CPM) with an excellent porosity of 73.82% and an ultrahigh liquid electrolyte uptake of 900 wt %, prepared by the solution casting method. Li 2 SO 4 as an electrolyte salt and various concentrations of Al 3+ as additives were used for fabricating the gel polymer electrolyte (GPE). On adding Al 3+ into the Li 2 SO 4 electrolyte, dissociative water and bound water in Li + solvation interact with Al 3+; this affects water molecule activity and reduces Li + solvation. While the presence of Al 3+ electrolyte exhibits better electrochemical stability under a high operating voltage of 1.6 V, the highest specific capacitance of a supercapacitor (SC) is 136 F g –1 at 1.0 A g –1, and it has 91% initial capacitance retention after 20 000 charge–discharge cycles, which is higher than that of the Li 2 SO 4 electrolyte. This work provides a path for designing a high-output-voltage aqueous supercapacitor via electrolytes and the membrane strategy.