In-situ Cross-Linked Multifunctional Polymer Electrolyte Buffer Layers for High-Performance Garnet Solid-State Lithium Metal Batteries

The garnet Li6.75La3Zr1.75Ta0.25O12 (LLZTO) is one of the most promising electrolytes for commercial appli-cation since of its high ionic conductivity and good stability to Li. Nevertheless, the poor electrolyte/elec-trode interface contact enlarges the interface impedance of all-solid-state battery (ASSB). Herein, a multifunctional polymer electrolyte (MPE) interface buffer layers are formed on both sides of LLZTO sur-face through an in-situ crosslinking strategy to improve the interface contact with electrodes, which can facilitate uniform Li' deposition/exfoliation and inhibit the growth of lithium dendrites as evidenced by the reduced interface impedance (103.4 X cm2), the increased critical current density (CDD, 1.2 mA cm-2) and 950 h stable cycle of Li symmetric cells at 0.7 mA cm-2, 0.7 mA h cm-2. Besides, the MPE layer can reduce the magnitude of electric field at the interface and widen the electrochemical window (0-5.2 V). The stable interface of the LLZTO@MPE/cathode enables the full cells matching with the LiFePO4 (LFP) and LiNi0.5Co0.2Mn0.3O2 (NCM523) cathodes to deliver superior electrochemical performances. Specifically, the Li/MPE@LLZTO@MPE/LFP delivers a capacity retention rate of 87% after 200 cycles at 1 C. When it's matched with the NCM523 cathode, a capacity retention rate of 98% is retained after 100 cycles at 1 C. This work provides an effective and simple way to build good-interface-contact and long-lifespan garnet solid-state lithium metal batteries (SSLMBs).(c) 2023 Elsevier Inc. All rights reserved.