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.