Weaving strength and conductivity: spider silk-modulated polymer electrolytes for high-performance all-solid-state lithium-metal batteries

Abstract

Spider silk, renowned for its remarkable mechanical properties and unique molecular architecture, offers a solution for enhancing solid polymer electrolytes for all-solid-state lithium-metal batteries. This study demonstrates the effectiveness of bioengineered spider silk proteins in creating a truly solid phase polyethylene oxide (PEO)-based electrolyte that overcomes the challenge of balancing high ionic conductivity and robust mechanical integrity. Incorporating bioengineered major ampullate spidroin variants, R1 and R2, into PEO-based electrolytes results in simultaneous improvements in mechanical properties and ionic conductivity. Notably, R1- and R2-reinforced PEO exhibits up to 248.7 MJ m⁻³ toughness, twice that of natural dragline silk. Furthermore, the PEO/R2 SPEs with Li salt demonstrate a 35-fold increase in ionic conductivity (3.0 × 10⁻⁴ S cm⁻¹ at 30 °C), a 10-fold improvement in toughness, and a 4-fold increase in interfacial adhesion compared to pure PEO-based SPE. These enhancements lead to effective suppression of Li dendrite penetration in Li plating/stripping tests (4000 hours without short-circuiting at 0.2 mA cm⁻²) and superior cycling performance in LiFePO₄|Li cell tests at 25 °C (134.8 mA h g⁻¹ initial capacity and 94% retention after 70 cycles). This bio-inspired strategy facilitates the development of safer, more efficient, and environmentally friendly energy storage systems.