Rocking-Chair Proton Batteries with Conducting Redox Polymer Active Materials and Protic Ionic Liquid Electrolytes

Rechargeable batteries that use redox-active organic compounds are currently considered as an energy storage technology for the future. Functionalizing redox-active groups onto conducting polymers, to make conducting redox polymers (CRPs) can effectively solve the low conductivity and dissolution problems of redox-active compounds. Here we employ a solution-processible postdeposition polymerization (PDP) method, where the rearrangements ensured by partial dissolution of intermediated trimer during polymerization was found significant to produce high performance CRPs. We show that quinizarin (Qz) and naphthoquinone (NQ) based CRPs can reach their theoretical capacity through optimization of the polymerization conditions. Combining the two CRPs, with the Qz-CRP as cathode and the NQ-CRP as anode, and a protic ionic liquid electrolyte, yields a 0.8 V proton rocking-chair battery. The conducting additive-free all-organic proton battery exhibits a capacity of 62 mAh/g and a capacity retention of 80% after 500 cycles using rapid potentiostatic charging and galvanostatic discharge at 4.5 C.