Synthesis and electrochemical properties of a new class of low-glass-transition-temperature electrochemical cell polymers based on polyalkoxysiloxanes is described. Unlike ethyleneoxide (EO)-based polymers, these materials are oxidatively stable above 4.2 V, the operating voltage of high energy cells that use cathode materials such as nickel cobalt aluminum oxide (NCA) and nickel cobalt manganese oxide (NCM). Use of these electrochemical cell polymers as catholyte alternatives to PEO in high voltage cells is described.