An integrated solvent-free modification and composite process of Li6.4La3Zr1.4Ta0.6O12/Poly(ethylene oxide) solid electrolytes: Enhanced compatibility and cycle performance

With the increasing demand for higher energy density Lithium-ion batteries, the battery safety issue has gained growing attention. Solid-state electrolytes (SSEs) are considered a promising solution to the volatilization and inflammable problems of the traditional liquid electrolytes. In this work, we propose a novel solvent-free modification process using stearic acid as a modifying agent for LLZTO/PEO hybrid electrolytes. Compared to the conventional solvent-casting process, the new one integrates surface modification and composite in a successive solvent-free step, so it can greatly improve the process efficiency and meet the requirement of green chemistry. Fourier Transform Infrared spectrometry (FTIR), X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM) observation confirm the structure of the uniform coating layer. The solvent-free modification and composite process are proved to significantly inhibit the agglomeration of LLZTO particles and the side reactions on particle surfaces in the polymer matrix by using Scanning Electron Microscope (SEM) and Thermal Gravimetric-Differential Thermal Analysis (TG-DTA) characterization. Thus, the prepared electrolyte has the ionic conductivity of up to 8.3 × 10−4 S cm−1 at 70 °C. It has better electrochemical stability as well, which can achieve about 900 cycles in Li symmetric cells with a current density of 0.1 mA cm−2.