The Regulation of Ion Transport Microenvironment in Micropores to Precisely Construct Porous Polymer Electrolytes for Solid-State Lithium–Metal Batteries

Porous solid-state polymer electrolytes have emerged as promising candidates for next-generation batteries owing to their superior safety, excellent interfacial compatibility, and efficient ion transport properties. However, systematically tuning the Li⁺ solvent microenvironment within the micropores of PIMs (inherent microporous polymers) to significantly enhance Li⁺ conduction remains unexplored. Herein, we propose a strategy for performing microenvironmental engineering within microporous channels. By creating interconnected subnanometer-scale ion transport channels within a rigid and twisted PIM backbone, we precisely regulate the Li⁺ solvent interactions in the pore microenvironment. This dual optimization enables the porous polymer electrolyte to exhibit an excellent room-temperature ionic conductivity of 1.08 × 10^-3 S cm^-1, a high lithium-ion transference number (0.88), and wide electrochemical window (5.2 V). These superior electrochemical properties allow the assembled Li-Li symmetric battery to achieve stable deposition/plating over 1500 h at 0.1 mA cm^-2. Consequently, the assembled LFP|PIM-CONH₂|Li delivers an initial discharge specific capacity of 158.2 mAh g^-1 at 0.5 and 25 °C, with a capacity retention rate of 93.6% after 400 cycles. More notably, the assembled pouch cells still exhibit a high discharge specific capacity of 139.2 mAh g^-1 after folding and cutting under 0.5 C. Moreover, the introduction of our proposed nonflammable PIM-CONH₂ electrolyte represents a significant advancement, facilitating the transition toward the practical implementation of high-safety and high-energy-density solid-state batteries.