Building up ion-conduction pathways in solid polymer electrolytes through surface and pore functionalization of PVDF porous membranes with ionic conductors

Solid polymer electrolytes (SPEs) have received much research attention for the safety concerns about high energy density batteries. The major issues to be addressed for SPEs are relatively low ionic conductivity and poor electrolyte/electrode interfacial compatibility. In this work, lithium-ion-conduction pathways have been built up in SPEs through introduction of ion conductor-containing chains on the pore walls of porous PVDF membranes. SPEs employing the functionalized membranes as supporting matrix have been prepared through an in situ polymerization technique. The built-in ion-conduction pathways result in a 6.7-times of ionic conductivity to the corresponding SPEs, compared to the SPEs made with the neat PVDF support. The SPEs also exhibit an electrochemical stability window up to 4.5 V and a significant suppression on lithium dendrite formation. The corresponding LiFePO4/SPE/Li cells demonstrate a discharge capacity of 141 mAh g−1 at 0.1 C and a capacity retention of 95% after 100 charging/discharging cycles. The results provide a structural design and synthesis approach for conveniently building up lithium-ion transportation channels in SPEs for high performance lithium metal batteries.