Redox equilibrium of a zwitterionic radical polymer in a non-aqueous electrolyte as a novel Li⁺ host material in a Li-ion battery

Poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate-co- styrenesulfonate) was prepared and utilized as a Li⁺ host material for a cathode in a Li-ion battery. The polymer allowed high density incorporation of the Li⁺ ion per repeating unit at a positive redox potential near 0.6 V vs. Ag/AgCl. Redox equilibrium involving the Li⁺ migration was proved by the theoretical approach based on the Nernst equation as well as a microgravimetry analysis using an electrochemical quartz crystal microbalance technique. A cell fabricated with the polymer as the cathode-active material showed a high power rate capability with an average discharging potential near 3.9 V vs. the lithium metal anode.