In Situ Formed LiI Interfacial Layer for All-Solid-State Lithium Batteries with Li6PS5Cl Solid Electrolyte Membranes

PVDF-HFP via Localized Iodization as Interface Layer for All-Solid-State Lithium Batteries with Li6PS5Cl Films

All-solid lithium (Li) metal batteries (ASSLBs) with sulfide-based solid electrolyte (SEs) films exhibit excellent electrochemical performance, rendering them capable of satisfying the growing demand for energy storage systems. However, challenges persist in the application of SEs film owing to their reactivity with Li metal and uncontrolled formation of lithium dendrites. In this study, iodine-doped poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP) as an interlayer (PHI) to establish a stable interphase between Li metal and Li6PS5Cl (LPSCl) films is investigated. The release of I ions and PVDF-HFP produces LiI and LiF, effectively suppressing lithium dendrite growth. Density functional theory calculations show that the synthesized interlayer layer exhibits high interfacial energy. Results show that the PHI@Li/LPSCl film/PHI@Li symmetrical cells can cycle for more than 650 h at 0.1 mA cm-2. The PHI@Li/LPSCl film/NCM622 cell exhibits a distinct enhancement in capacity retention of ≈26% when using LiNi0.6Mn0.2Co0.2O2 (NCM622) as the cathode, compared to pristine Li metal as the anode. This study presents a feasible method for producing next-generation dendrite-free SEs films, promoting their practical use in ASSLBs.

A Dynamically Stable Mixed Conducting Interphase for All-Solid-State Lithium Metal Batteries

All-solid-state lithium (Li) metal batteries (ASSLMBs) employing sulfide solid electrolytes have attracted increasing attention owing to superior safety and high energy density. However, the instability of sulfide electrolytes against Li metal induces the formation of two types of incompetent interphases, solid electrolyte interphase (SEI) and mixed conducting interphase (MCI), which significantly blocks rapid Li-ion transport and induces uneven Li deposition and continuous interface degradation. In this contribution, a dynamically stable mixed conducting interphase (S-MCI) is proposed by in situ stress self-limiting reaction to achieve the compatibility of Li metal with composite sulfide electrolytes (Li6 PS5 Cl (LPSCl) and Li10 GeP2 S12 (LGPS)). The rational design of composite electrolytes utilizes the expansion stress induced by the electrolyte decomposition to in turn constrain the further decomposition of LGPS. Consequently, the S-MCI inherits the high dynamical stability of LPSCl-derived SEI and the lithiophilic affinity of Li-Ge alloy in LGPS-derived MCI. The Li||Li symmetric cells with the protection of S-MCI can operate stably for 1500 h at 0.5 mA cm-2 and 0.5 mAh cm-2 . The Li||NCM622 full cells present stable cycling for 100 cycles at 0.1 C with a high-capacity retention of 93.7%. This work sheds fresh insight into constructing electrochemically stable interphase for high-performance ASSLMBs.

Insight into Dendrites Issue in All Solid-State Batteries with Inorganic Electrolyte: Mechanism, Detection and Suppression Strategies

All solid-state batteries (ASSBs) are regarded as one of the promising next-generation energy storage devices due to their expected high energy density and capacity. However, failures due to unrestricted growth of lithium dendrites (LDs) have been a critical problem. Moreover, the understanding of dendrite growth inside solid-state electrolytes is limited. Since the dendrite process is a multi-physical field coupled process, including electrical, chemical, and mechanical factors, no definitive conclusion can summarize the root cause of LDs growth in ASSBs till now. Herein, the existing works on mechanism, identification, and solution strategies of LD in ASSBs with inorganic electrolyte are reviewed in detail. The primary triggers are thought to originate mainly at the interface and within the electrolyte, involving mechanical imperfections, inhomogeneous ion transport, inhomogeneous electronic structure, and poor interfacial contact. Finally, some of the representative works and present an outlook are comprehensively summarized, providing a basis and guidance for further research to realize efficient ASSBs for practical applications.