Porous Wood Composite as a Green Approach for Enhancing Electrochemical Performance of Gel Polymer Electrolytes for Supercapacitors

Delignified wood (DW) is a kind of environment-friendly porous material, and its unique hierarchical orous structure and excellent wettability are conducive to the rapid transfer and storage of ions, which can be used as electrolyte matrix of supercapacitors. In order to solve the deficiency of mechanical properties of DW as electrolyte materials, a novel cross-linked polyurethane (CPU) with high water absorption is designed as a reinforced matrix to improve the mechanical properties of electrolytes while maintaining high ionic conductivity. First, DW is immersed in CPU precursor solution, and the DW/CPU composite (W-CPC) is obtained by thermal crosslinking. Finally, W-CPC is soaked in 1 M LiClO₄ aqueous electrolyte to obtain the composite gel polymer electrolyte (W-CPC-GPE). Benefiting from the good hydrophilicity of W-CPC, the anisotropic vertical channels inside the DW, and the synergism of hydrogen bond and covalent bond. The highest ionic conductivity and mechanical strength of W-CPC-GPE are 3.5×10^-2 S cm^-1 and 0.67 MPa, respectively. The W-CPC-5-G based supercapacitor exhibits a high specific capacitance of 146.52 F g^-1 and favorable capacitance retention rate of 90.7 % after 5000 cycles. The results show that compounding with DW is an efficient and green way to develop high-performance gel polymer electrolytes for supercapacitors.