Interfacial dual-modulation via electrostatic shielding and dead lithium reactivation for solid-state lithium energy storage

Abstract

Solid-state lithium metal battery with high energy density suffers from a short lifespan owing to the ceaseless generation of inactive lithium and electrically-isolated lithium at electrode/electrolyte interface. One strategy for interfacial dual modulation is proposed by introducing a KI-modified solid polymer electrolyte (SPE-KI). The utilization of lithium sources is significantly improved through the electrostatic shielding effect of trace K⁺ and reactivation of the dead lithium by I⁻/I₃⁻ redox couple. Further sensitive in situ/ex situ characterizations and finite element simulations quantify the structural distribution and specific content of solid electrolyte interphase (SEI) generated by KI interfacial dual-modulation. The resulted Li|SPE-KI|LiFePO₄ cell displays an excellent cycling performance with 82.7 % capacity retention after 1600 cycles at 2 C. Such interfacial dual-protection strategy stemmed from trace functional additives broadens design horizons for solid-state lithium energy storage.