Ionic Porous Organic Polymers Synthesized Using Solvothermal and Mechanochemical Methods as Solid Electrolytes for Lithium Metal Batteries

Lithium metal batteries (LMBs) have considerable potential to become the next generation of energy storage devices, because of their high energy density. However, when used with liquid electrolytes, dendrite growth and thermal runaway can cause serious safety problems. Solid-state electrolytes with high Li⁺ conductivity, durability, and stability can effectively solve these problems. However, existing solid electrolytes do not meet the desirable criteria of having low interfacial contact, high electrochemical stability, high conductivity, and low manufacturing cost. Herein, we demonstrate that Li⁺-coordinated silicate and sulfonate porous organic polymers (denoted as Li⁺@Si-S-POPs) synthesized using solvothermal (ST) and mechanochemical (MC) methods can be used as solid electrolytes for LMBs. Benefiting from the incorporated ionic groups, permanent porosity, and low interfacial resistance, products synthesized using ST and MC methods exhibited high Li⁺ conductivity values of 1.1 × 10^-4 and 1.5 × 10^-4 S cm^-1 at room temperature and Li⁺ transference numbers of 0.94 and 0.96, respectively. Such excellent conduction behaviors facilitate high Li plating/stripping stability on Li metal electrodes, demonstrating the potential of Li⁺@Si-S-POPs for use in solid-state LMBs.