A binary contact-curved nano-shield design for separators to suppress dendrite formation for stable lithium-metal batteries

The development of mechanically robust interfacial barriers is critical to address lithium (Li) dendrite penetration through separators in Li-metal batteries (LMBs) during prolonged cycling. Herein, we propose a novel binary contact-curved (BC) nano-shield separator architecture, characterized by two fibers positioned side-by-side in close contact, forming a unique curved interface. Mechanical analysis and multiphysics simulations demonstrate that the geometry of the BC separator effectively mitigates localized stress, while its enhanced effective Young's modulus compared to the single-curved (SC) counterpart significantly suppresses Li dendrite growth. Besides, the unique structure of the BC separator endows it with superior electrolyte affinity, achieving exceptional wettability and enhanced ionic conductivity. As a proof of concept, Li||LiFePO₄ (LFP) and Li||sulfurized polyacrylonitrile (SPAN) full cells using this BC separator demonstrate outstanding electrochemical performance, including extended cycle life and distinguished rate capability. Furthermore, the BC separator also shows outstanding compatibility with a range of alkali metal batteries across diverse electrolyte systems, consistently delivering significant performance improvements. This work establishes a universal design paradigm for next-generation separators, advancing the development of safe, high-performance alkali metal anode batteries for energy storage applications.