Designing the Interface Layer of Solid Electrolytes for All-Solid-State Lithium Batteries

Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is one of the most attractive solid-state electrolytes (SSEs) for application in all-solid-state lithium batteries (ASSLBs) due to its advantages of high ionic conductivity, air stability and low cost. However, the poor interfacial contact and slow Li-ion migration have greatly limited its practical application. Herein, a composite ion-conducting layer is designed at the Li/LATP interface, which a MoS₂ film is constructed on LATP via chemical vapor deposition, followed by the introduction of a solid polymer (SP) liquid precursor to form a MoS₂@SP protective layer. This protective layer not only achieves a lower Li-ion migration energy barrier, but also adsorbs more Li-ion, which is able to promote interfacial ion transport and improve interfacial contacts. Thanks to the improved migration and adsorption of Li-ion, the Li symmetric cell containing LATP-MoS₂@SP exhibits a stable cycle of more than 1200 h at 0.1 mA cm^-2. More remarkably, the capacity retention of the full cell assembled with LiFePO₄ cathode is as high as 86.2% after 400 cycles at 1 C. This work provides a design strategy for significantly improving unstable interfaces of SSEs and realizing high-performance ASSLBs.