Anthraquinone-functionalized reduced graphene oxide as a negative electrode for aqueous Ni(OH)₂/NiOOH hybrid cells

Aqueous organic-inorganic hybrid systems offer a safe and sustainable platform for high-power energy storage, yet mitigating redox instability in carbon-supported organic electrodes remains challenging. This study reports a full-cell pairing a reduced graphene oxide (RGO) electrode, covalently functionalized with anthraquinone (AQ) units, with a Ni(OH)₂ positive electrode in alkaline electrolyte. The nitrene-grafted RGO-methyl AQ material immobilizes AQ units on a conductive carbon framework, mitigating dissolution and enabling effective electron transfer.Electrochemical analysis reveals a hybrid charge-storage mechanism combining reversible AQ redox with capacitive buffering from RGO. The RGO–methyl AQ‖Ni(OH)₂/NiOOH full-cell delivers an average operating voltage of 0.89 V and a specific capacity of 139.6 mAh g−1 (anode mass) at 0.09C. It retains 84 % of its capacity (51 mAh g−1) after 101 cycles at 12.7C and remains operational at 33C. The anode-based energy density decreases from 61 Wh kg−1 at 2C to 34 Wh kg−1 at 33C. When projected to a practical device assuming a 25–40 % active-mass fraction, the estimated power density (281–449 W kg−1) lies within the lower range of commercial high-power NiMH systems.These results identify covalently grafted AQ-RGO as a promising electroactive anode candidate for sustainable, critical-metal-free NiMH-type chemistries, while explicitly highlighting performance limits associated with interfacial instability.