Construction of a High-Performance Composite Solid Electrolyte Through In-Situ Polymerization within a Self-Supported Porous Garnet Framework

Abstract

Composite solid electrolytes (CSEs) have emerged as promising candidates for safe and high-energy-density solid-state lithium metal batteries (SSLMBs). However, concurrently achieving exceptional ionic conductivity and interface compatibility between the electrolyte and electrode presents a significant challenge in the development of high-performance CSEs for SSLMBs. To overcome these challenges, we present a method involving the in-situ polymerization of a monomer within a self-supported porous Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZT) to produce the CSE. The synergy of the continuous conductive LLZT network, well-organized polymer, and their interface can enhance the ionic conductivity of the CSE at room temperature. Furthermore, the in-situ polymerization process can also construct the integration and compatibility of the solid electrolyte-solid electrode interface. The synthesized CSE exhibited a high ionic conductivity of 1.117 mS cm^-1, a significant lithium transference number of 0.627, and exhibited electrochemical stability up to 5.06 V vs. Li/Li⁺ at 30 °C. Moreover, the Li|CSE|LiNi_0.8Co_0.1Mn_0.1O₂ cell delivered a discharge capacity of 105.1 mAh g^-1 after 400 cycles at 0.5 C and 30 °C, corresponding to a capacity retention of 61%. This methodology could be extended to a variety of ceramic, polymer electrolytes, or battery systems, thereby offering a viable strategy to improve the electrochemical properties of CSEs for high-energy-density SSLMBs.

Keywords: Composite solid electrolyte; LiF-and B-rich interphase layers; Scalable tape-casting method; Self-supported porous Li6.4La3Zr1.4Ta0.6O12.