Activating Redox Chemistry of Quinones for High Energy Density Aqueous Sodium-Ion Batteries
Yizhong Gou, Nini Liu, Yu Peng, Jingwen Zhang, Jian Peng, Jiantao Han, Yunhui Huang, Chun Fang
Abstract
Anode materials with high capacity and suitable redox potential are crucial for improving the energy density of aqueous sodium-ion batteries (ASIBs). And organic anode materials play a promising role due to their tunable electrochemical performance. However, the insufficient electroactive sites lead to a low capacity, hindering the elevation of energy density. Thus, it is essential to design organic molecules with multiple redox-active sites. Herein, we propose a strategy to activate redox sites by regulating the spatial distribution of delocalized electrons within the conjugation system, and the quinone rings are successfully activated as new reversible Na-ion storage sites via enhancing the electron density. The obtained 2,5-dihydroxy-1,4-benzoquinonatocobalt (Co-DHBQ) with electroactive quinone rings exhibits a superior capacity of 183 mA h g –1 accompanied by a multiple-electron transfer. Benefiting from the high capacity, the Co-DHBQ||Na 2 Mn[Fe(CN) 6 ]·2H 2 O (MnHCF) full cell outputs a ultrahigh energy density of 110 W h kg –1 (based on the total active material mass of the anode and cathode) with a lifespan of 3000 cycles. This work proposes a strategy to activate new redox sites, providing a new impetus for designing high-performance organic electrode materials and developing high energy density ASIBs.