Anion-Rocking Chair Batteries with Tuneable Voltage using Viologen- and Phenothiazine Polymer-based Electrodes

Organic battery electrode materials offer the unique opportunity for full cells to operate in an anion-rocking chair mode. For this configuration a pair of p-type redox-active electrode materials is required with a substantial potential gap between their redox processes. We herein investigate viologen-functionalized polystyrenes as negative electrode paired with a phenothiazine polymer as positive electrode in all-organic full cells. The 10 % crosslinked viologen polymer X₁₀ -PVBV gave better performance than the linear PVBV and was employed in a full cell as negative electrode with cross-linked poly(3-vinyl-N-methylphenothiazine) (X-PVMPT) as positive electrode. Three cell configurations regarding the voltage range were investigated, of which one with an operating potential of 0.9 V gave the highest performance. The full cell delivered a specific discharge capacity of 64 mA h g^-1 (of X-PVMPT) in the first cycle and a capacity retention of 79 % after 100 cycles. This is one of only few reported anion rocking chair all-organic cells and the first employing a phenothiazine-based positive electrode material.