Natural Supra-Molecular Structure Engineering for High-Performance Potassium Batteries Separator

摘要

Although potassium batteries (KBs), such as potassium-metal batteries andpotassium-ion batteries, promise low cost and high-energy density, specializedseparators are not available that can satisfy the KBs operations. In thiswork, a hierarchical porous cellulose (HPC) separator with high-performance,by engineering of the natural supra-molecular structure of cellulose, isreported. The supra-molecular and hierarchical structure of cellulose providesthe separator with high porosity, excellent mechanical properties, superiorelectrolyte wettability, and stable thermal performance. The incorporationof small pore size (0.64 μm) and suitable tortuosity (1.83) reveal that theseparator enables uniform current distribution and inhibits the puncturing ofK dendrites. Thus, a lifespan of more than 1000 h for a K//K symmetric cellis achieved without short-circuiting. Benefiting from the high K+ transferencenumber (0.69), graphite//K and Prussian blue (PB)//K cells with HPC separatorsexhibited pre-eminent cycling stability (400 and 200 cycles, respectively)and high-rate performance. Moreover, the PB//graphite full cell with HPCseparator is shown to deliver a reversible capacity of 86 mAh g~(?1) with 100cycles. This novel HPC separator provides a possibility for the sustainabledevelopment of KBs and other energy storage systems by the rational structuralmodification of plants.