A high strength and dendrite free low-temperature nanocellulose composite PVA gel electrolyte for zinc ion batteries

Abstract

With the increasing global energy demand, water-based zinc ion batteries have received widespread attention. However, the growth of zinc dendrites and the occurrence of side reactions on the surface of zinc electrodes can affect the capacity of zinc ion batteries, hindering their practical application. This study reports a multifunctional dendrite-free gel electrolyte prepared by introducing carboxyl modified nanocellulose (C-CNFs) into a polyvinyl alcohol (PVA) based gel electrolyte. At the same time, we also add the antifreeze agent dimethyl sulfoxide (DMSO) to it, which greatly improves the low-temperature performance of gel electrolytes. The rich functional groups on the surface of C-CNFs can effectively adjust the continuous movement of PVA and improve the mechanical strength of the gel electrolyte, and at the same time, they can effectively absorb zinc ions, enable uniform distribution of zinc ions in the electrolyte, reduce the interface concentration gradient, and reduce the occurrence of side reactions, so that the zinc ion deposition is more uniform, and dendrite free deposition is achieved. The polyaniline zinc ion battery assembled with this electrolyte can stably cycle over 3000 times at room temperature, with a capacity retention rate of 83.23%. At −20 °C, the capacity retention rate reaches 60% after 1200 cycles.