Polymer electrolytes offer increased safety and stability as compared to liquid electrolytes, yet there are a number of new challenges that polymer electrolytes introduce. A novel polymer electrolyte, as disclosed herein, is an ionically-conductive polymer with a backbone that is both highly flexible and highly conductive with high conductivity pendant chains attached, thus increasing the concentration of lithium coordination sites and improving ionic conductivity. Previous strategies for comb-type conductive polymers have focused on attaching either conductive pendant chains to a flexible non-conductive backbone or conductive pendant groups to a marginally flexible conductive backbone.