Lipoic Acid-Assisted In Situ Integration of Ultrathin Solid-State Electrolytes

Abstract

Ultrathin solid-state electrolytes (SSEs) have contributed to high-energy-density lithium-ion batteries (LIBs). However, when reducing thickness of SSEs, mechanical properties will inevitably deteriorate, even increasing the safety hazards. In this work, we developed an in-situ integration strategy to form an ultrathin SSE by combining a lipoic acid-assisted semi-interpenetrating polymer network and an ultrathin porous membrane. With this strategy, the thickness of the obtained SSE (named LA-SSE) is only 10 μm, and the LA-SSE possesses extraordinary mechanical performances to suppress the growth of lithium dendrites. Meanwhile, the flexible LA-SSE presents anionic conductivity of 0.036 mS cm–1 and promotes interfacial compatibility between the lithium anode and the electrolyte. By employing LA-SSE as the electrolyte, the assembled Li∥LA-SSE∥Li symmetric cell operated with long-term cycling (more than 3000 h), and the LiFePO4∥LA-SSE∥Li full battery worked steadily over 200 cycles at 0.5 C with a capacity retention of 84% at room temperature. This work provides a promising strategy for designing ultrathin SSEs, with satisfactory mechanical properties, excellent interfacial compatibility, and safety, for LIBs.