Low-Cost Hollow Mesoporous Polymer Spheres and All-Solid-State Lithium, Sodium Batteries

A practical, low-cost synthesis of hollow mesoporous organic polymer (HMOP) spheres is reported. The electrochemical properties of Li⁺/Na⁺-electrolyte membranes with these spheres substituting for oxide filler particles in poly(ethylene oxide) (PEO)-filler composite are explored. The electrolyte membranes are mechanically robust, thermally stable to over 250 °C, and block dendrites from a metallic-lithium/sodium anode. The Li⁺/Na⁺ transfer impedance across the lithium/sodium-electrolyte interface is initially acceptable at 65 °C and scavenging of impurities by the porous-spheres filler lowers this impedance relative to that with Al₂O₃. All-solid-state Li/LiFePO₄ and Na/NaTi₂(PO4)₃ cells give stable discharge capacity of ≈130 and 80 mAh g^-1, respectively, at 0.5 C and 65 °C for 100 cycles.