Halide-sulfide bilayer electrolytes for LiFePO4-based all-solid-state batteries

Abstract

All-solid-state lithium batteries (ASSLBs) are increasingly regarded as one of the next-generation energy storage technologies, offering good abuse tolerance, a wide operating temperature range, and a simplified battery system suitable for automotive applications. In the pursuit of cost-effectiveness and battery thermal stability, LiFePO₄ (LFP) has recently attracted widespread attention in both industry and academia as a cathode active material for ASSLBs. However, the poor interfacial compatibility between the electrode and electrolytes has significantly hindered the development of LFP-based ASSLBs. In this study, an advanced Li₂ZrCl₆ (LZC) – Li_9.54Si_1.74P_1.4S_11.7Cl_0.3 (LiSiPSCl) bilayer electrolyte is rationally designed for LFP-based ASSLBs, aiming to simultaneously achieve favorable interfacial compatibilities with both the LFP cathode layer and alloy anode layer. As a result, the developed LFP-LZC/LZC/LiSiPSCl/Li–In ASSLB can not only deliver a high initial discharge capacity of 144.9 mA h g⁻¹, but also manifest a high-capacity retention up to 89% after 400 cycles at the current density of 1C. The strategy used in this work sheds light on a promising method to engineer stabilized interfaces for LFP-based ASSLBs.