The multi-scale dissipation mechanism of composite solid electrolyte based on nanofiber elastomer for all-solid-state lithium metal batteries.

Abstract

Developing next generation batteries necessitates a paradigm shift in the way to engineering solutions for materials challenges. In comparison to traditional organic liquid batteries, all-solid-state batteries exhibit some significant advantages such as high safety and energy density, yet solid electrolytes face challenges in responding dimensional changes of electrodes driven by mass transport. Herein, the critical mechanical parameters affecting battery cycling duration are evaluated based on Spearman rank correlation coefficient, decoupling them into strength, ductility, stiffness, toughness, elasticity, etc. Inspired by the statistical results to apply the materials with stress-relief mechanisms, we propose an elastic solid electrolyte based on the multi-scale mechanical dissipation mechanism. The Li_6.4La₃Zr_1.4Ta_0.6O₁₂/thermoplastic polyurethanes curled fibrous framework is designed and prepared by side-by-side electrospinning technique, serving as elastic source and ion-transport pathways for the composite with poly(ethylene oxide) matrix. Dominated sequentially by electrolyte deformation, network orientation, extendable fibers and molecular chain unfolding, the prepared elastic electrolyte exhibits excellent resilience, compression and puncture resistance. Meanwhile, the curled fast ion conductor fibers can also provide the transport pathways along the component of transmembrane direction, endowing the composite electrolyte with an ionic conductivity of 1.46 × 10^-4 S cm^-1 at 30 °C. A low capacity decay of 0.011 % per cycle at 2 C in assembled LiFePO₄/Li battery and an excellent lifespan of 1000 cycles at 50 °C in LiNi_0.8Mn_0.1Co_0.1O₂/Li battery can be achieved. The elastic electrolyte system presents a promising strategy for enabling stable operation of high-energy all-solid-state lithium batteries.