Molecular Design of Polymeric Metal-Organic Nanocapsule Networks for Solid-State Lithium Batteries

Solid-state electrolytes (SSEs) have emerged as high-priority materials for ensuring the safe operation of solid-state lithium (Li) batteries. However, current SSEs still face challenges of balancing stability and ionic conductivity, which limits their practical applications in solid-state Li batteries. Here, we report a general strategy for achieving high-performance SSEs by constructing a Li⁺-conducted polymeric metal-organic nanocapsule (PolyMONC(Li)) network through molecular design. With the unique cage structure and pore size, metal-organic nanocapsule (MONC) can achieve excellent anion confinement effects. The PolyMONC(Li) network with continuous Li⁺ conduction pathways serves as a solid electrolyte exhibiting a high ionic conductivity (0.18 mS cm^-1 at 25 °C) and a high Li⁺ transference number (0.83). Combining the two superiorities of optimal balance between mechanical strength and excellent Li⁺ conductivity, the PolyMONC(Li) can still restrain the dendrite growth and prevent Li symmetric batteries from short-circuiting even over 900 h cycling. The PolyMONC(Li)-based SSEs Li-metal batteries achieved a higher specific capacity than common polymer electrolytes such as polyethylene oxide-based SSE. Additionally, taking advantage of the PolyMONC(Li) electrode binder, the solid-state Li-O₂ battery achieves a stable cycling over 400 cycles. This work provides a comprehensive guideline for developing porous solids from molecule design to practical application.