In situ formation of a dual-function interlayer for enhanced cycling stability in solid state lithium battery

Abstract

Garnet-type LLZO is a promising solid electrolyte for solid-state lithium batteries as its superior performance. However, the mismatch in lithium-ion migration at the Li/LLZO interface, and rapid electron migration within LLZO, facilitates the growth of lithium dendrites. Herein, an interlayer consisted of multiphase metal sulfides (ZnS, In₂S₃ and Li₂S) is synthesized by in-situ reaction between a ZnIn₂S₄ (ZIS) modification layer on LLZO and lithium anode. ZnS promote lithium ion migration at the interface, and In₂S₃ and Li₂S prevent electron leakage from the anode, effectively inhibiting the formation of lithium dendrites. Benefiting from this dual-function interlayer design, the symmetrical lithium battery achieve a low interfacial impedance of 2.5 Ω cm², a high critical current density of 1.6 mA cm⁻² at 25 °C and 3.4 mA cm⁻² at 60 °C, and excellent cycling stability over 3000 h at 0.3 mA cm⁻² (25 °C) and 1000 h at 1 mA cm⁻² (60 °C). Furthermore, the LiFePO₄/ZIS-LLZTO/Li battery presents a high discharge capacity of 129.32 mAh·g⁻¹ at 1 C, with 80 % capacity retention after 600 cycles. This work lays a foundation for developing garnet-based solid-state batteries with enhanced long-term cycling performance.