Phenazinetetrone electrode for high-energy-density organic batteries via oxygen- and nitrogen-based redox reactions

The use of redox-active organic compounds that exhibit multielectron transfer reactions as an electrode material can effectively increase the capacity and energy density of rechargeable lithium batteries. Herein, we propose an organic compound, phenazinetetrone (PZTO), a high-energy-density molecular unit with redox-active carbonyl and imine moieties. Its theoretical capacity reaches as high as 670 mAh/g. The synthesized PZTO exhibits a high gravimetric energy density, although there is room for cycling stability. Solid-state nuclear magnetic resonance measurements and theoretical calculations reveal that the PZTO particles maintain a π-stacked moiety and band-like electronic structure in their crystals even when Li+ ions are inserted. Furthermore, a thousands-fold conductivity increase by Li+ insertion was experimentally confirmed. This mechanism can explain the high utilization of many other organic electrode materials that have been reported so far and dispel concerns regarding the practical applications of these organic compounds. Redox-active organic compounds that exhibit multielectron transfer reactions are promising electrodes for lithium batteries. Here, phenazinetetrone electrodes with redox-active carbonyl and imine moieties achieve a theoretical capacity as high as 670 mAh/g.