In-Situ Li₂Se Interface Engineering in NiSe-Incorporated PVDF Electrolytes for High-Rate and Dendrite-Resistant Solid-State Lithium Batteries

Solid-state lithium metal batteries (SSLMBs) face critical challenges, including low ionic conductivity, unstable electrode–electrolyte interfaces, and lithium dendrite growth issues. To address these issues, we designed a PVDF-based composite electrolyte embedded with NiSe nanosheets (PVDF-NS). The two-dimensional NiSe facilitated the in situ formation of Li2Se at the interface, promoting dendrite suppression by enhancing Li+ transport (room-temperature ionic conductivity: 5.53 × 10–4 S·cm–1; transference number: 0.449) and constructing a stable SEI layer. Notably, PVDF-NS supported Li||Li symmetric cells demonstrated excellent stability for over 2000 h at 0.2 mA·cm–2. When paired with NCM811 cathodes, full cells demonstrated 86.3% capacity retention over 300 cycles at 2 C. Additionally, the electrolyte exhibited high oxidative stability (4.83 V vs Li+/Li) and retained a capacity of 65.6 mAh·g–1 at 5 C, underscoring its practical applicability. This interfacial engineering approach presents a scalable and effective route for developing durable, high-performance solid electrolytes for next-generation SSLMBs.