Biomimetic and biodegradable separator with high modulus and large ionic conductivity enables dendrite-free zinc-ion batteries

The advancement of aqueous zinc-based batteries is greatly restricted by zinc dendrites. One potential solution to this challenge lies in the employment of high-modulus separators. However, achieving both high modulus and large ionic conductivity in a single separator remains a formidable task. Inspired by the wood architecture, this study breaks this trade-off by designing an anisotropic and biodegradable separator. This design significantly improves the modulus along the oriented direction while simultaneously facilitating fast Zn2+ ion transport through aligned vertical channels. Additionally, this configuration resolves the contradiction between low separator thickness and good dendrite-inhibition capability. These benefits are supported by finite element simulations and comprehensive experimental validation, which also underscore the critical role of modulus enhancement for separators. By employing the anisotropic separator, a prolonged life span is realized for Zn||Zn cells, along with improved cyclability in full batteries. This work presents a strategy for separator modification towards dendrite-free metal batteries.