The construction of multifunctional solid electrolyte interlayers for stabilizing Li6PS5Cl-based all-solid-state lithium metal batteries†

The electrochemical performance of all-solid-state Li metal batteries (ASSLMBs) can be improved by resolving the challenges triggered by the uncontrolled growth of Li dendrites throughout the solid electrolytes (SEs). Herein, a well-defined composite of micro-Li₆PS₅Cl (LPSC) and nano-Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is designed as a LPSC–LATP interlayer sandwiched between LPSC electrolytes for ASSLMBs. This fabrication exhibits electron-blocking functionalities, which reduce the probability of reaction with Li⁺ ions for the formation of anode-initiated and grain boundary (GB)-initiated dendrites. More importantly, it also creates localized eliminated micro-environments of Li dendrites through the high transient reactivity between them, and the remaining cracks can be dynamically and effectively filled by decomposition products, thereby clearly suppressing Li dendrite nucleation, propagation and penetration as well as simultaneously contributing to the enhancement of battery performance and stability. With this approach, a fine-tuned LPSC–LATP (8S–2O) interlayer enables symmetrical Li/LPSC/8S–2O/LPSC/Li cells to achieve an ultra-high critical current density (CCD) of over 5 mA cm⁻² at room temperature, and ultra-long-term cycling at a current density of 10 mA cm⁻² for over 1600 h. Additionally, ASSLMBs employing commercial LiCoO₂ cathodes can deliver exceptional durability, with an extremely high 85.6% retention of initial discharge capacity and coulombic efficiency (CE) of >99.6% after 1200 cycles at 1C (1.28 mA cm⁻²). These experimental batteries demonstrate the application potential of this configuration of SEs for the commercialization of ASSLMBs.