Asymmetry-structure electrolyte with rapid Li+ transfer pathway towards high-performance all-solid-state lithium–sulfur battery

Abstract

All-solid-state lithium–sulfur (Li–S) battery, with solid state electrolyte (SSE) replacing liquid electrolyte, is considered as promising candidate for next-generation energy storage devices due to the high capacity and safety. However, the fabrication of SSE with high ion conduction and efficient dendrite suppression remains a daunting challenge. Herein, an asymmetric Li0.33La0.557TiO3 (LLTO) framework with porous layer and dense layer is designed and fabricated, followed by impregnating poly (ethylene oxide) (PEO) to prepare SSE. The continuous LLTO framework serves as rapid lithium ion (Li+) transfer pathway, imparting an excellent ionic conductivity of 1.49 × 10−4 S cm−1 at 30 °C, over 40 times higher than that of blank PEO. The presence of dense layer remarkably improves the compression strength of composite electrolyte and facilitates the Li+ uniform deposition, thus effectively suppressing the lithium dendrite growth. As a result, the assembled Li–S battery exhibits extraordinary cycling stability, which preserves a capacity of 907.6 mAh g−1 after 100 cycles with a Coulombic efficiency of ~ 99%. Meanwhile, the continuous PEO phase that rooted in the porous layer of framework also imparts composite electrolyte favorable flexibility and processability.