Electron cloud engineering enables low-potential multi-redox-center organic anodes: towards dendrite-free, high-energy aqueous zinc-ion batteries

Abstract

Developing organic anode materials to fabricate zinc metal-free zinc ion batteries (ZF-ZIBs) is a prospective strategy to address the safety risks aroused by zinc dendrite. However, previously reported organic anodes are often criticized for their high potentials or low capacities. Here, an enlarged redox-active π-conjugated molecule, diquinoxalino[2,3-f:2′,3′-h]quinoxalino-[2,3-i]phenazine-2,3,8,9,17,18,23,24-octam-ethoxy-13,28-dione (DQPOD), is developed based on the electron cloud regulation strategy. Notably, the incorporation of the eight methoxy groups effectively increases the electron cloud density of the conjugated system, thus enabling the material to obtain an eminently low average discharge potential (0.44 V vs. Zn/Zn²⁺), while the enlarged π-conjugated redox-active structure produces an exceptional theoretical capacity of 390.5 mAh g⁻¹ and distinguished electrochemical performance. As expected, DQPOD exhibits superior practical capacity (300.22 mAh g⁻¹ at 0.1 A g⁻¹), satisfying cyclic stability and excellent rate capability. The MnO₂/DQPOD full battery presents an average operating voltage of up to 0.81 V at 5 A g⁻¹ and an ultrahigh power density of 3636 W kg⁻¹. The novel molecular architecture engineering strategy of DQPOD not only furnishes a unique outlook about the design of organic anode materials but also contributes valuable insights to the ongoing discourse of high-safety, high-energy–density metal-ion battery systems.

Graphical Abstract

Low-potential multi-electron redox organic anodes for zinc ion batteries are developed through active centers combination and electron cloud regulation strategy.