Sea cucumber inspired “polymer-in-salt electrolyte” boosting dendrite-free and flexible lithium metal batteries

Abstract

The inherent coupling between lithium salt concentration and mechanical robustness, along with inadequate anode compatibility, constrain the practical application of “polymer-in-salt electrolytes” (PISEs). Inspired by biomimetic design principles, a sea cucumber mimetic multifunctional poly(vinyl chloride-co-2-(((2,2,3,3-tetrafluoropropoxy) carbonyl) amino) ethyl acrylate)-based solid polymer electrolyte (PVCTF-SPE) is developed through hydrogen-bond engineering, achieving liquid to solid phase transition via a solvent-free tape casting approach. The introduced multi −NH−···OC− hydrogen-bond interactions decouple the intrinsic trade-off in PISEs, endowing PVCTF-SPE with an ionic conductivity of 1.21 × 10⁻⁴ S cm⁻¹, exceptional stretchability (1380 % strain), and autonomous self-healing capability. Furthermore, the superior elastic deformation behavior and strong Li-PVCTF interfacial adhesion effectively mitigate interfacial impedance and suppress tip-induced Li dendrite growth, enabling stable Li deposition/stripping for 3800 h in Li/Li symmetric cells. The strategically engineered molecular structure also delivers an expanded electrochemical window (>4.8 V) and flame-retardant characteristics. A 1.5 Ah Li/LiFePO₄ pouch cell demonstrates stable cycling performance (100 cycles, 70 % capacity retention) even under 7.5 % tensile strain and passes rigorous safety tests. This hydrogen bond engineering provides a universal paradigm for developing solid electrolytes with synergistically enhanced ion transport and mechanical stability.