In Situ construction of PVDF/LLTO electrolyte with stable electrolyte/electrode interphase for integrated solid-state lithium batteries

Abstract

Solid-state lithium (Li) metal batteries (LMBs) are promising owing to enhanced safety and high energy density. However, the issues of Li dendrite growth and large electrolyte-electrode interfacial resistance still hinder their practical applications in LMBs. Here, a Li anode-electrolyte structure integration has been developed using in-situ chemical reactions between the polyvinylidene fluoride/Li3xLa2/3−xTiO3/N-methyl pyrrolidone (PVDF/LLTO/NMP) solution and the Li metal interphase. After gradually coating the PVDF/LLTO/NMP solution onto Li metal, NMP as catalyst, inducing PVDF reacted with Li spontaneously to form lithium fluorine (LiF), and the accompanying Ti4+ ions (in LLTO) are reduced to Ti3+ ions to form a LLTO ionic/electronic conductor (LixLLTO). After NMP evaporation, an ionic/electronic conductor protective layer of LiF/LixLLTO is created between the PVDF/LLTO electrolytes and Li metal. When applying the integrated solid-state Li batteries (ISSLBs), the protective layer can reduce interfacial resistance and the formation of Li dendrites by regulating the even Li deposition redistributing the Li-ion transport. As a result, the as-assembled LiNi0.8Co0.1Mn0.1O2/ISSLBs achieves an initial capacity of 181 mA h g−1 and retains 83% capacity after 200 cycles at 0.5 C. This design can be an effective strategy to tailor the properties of Li-metal anodes for achieving dendrite-free LMBs with high performance and high safety.