J. Mater. Sci. Technol. ›› 2025, Vol. 210: 10-19.DOI: 10.1016/j.jmst.2024.05.033

• Research Article • Previous Articles     Next Articles

Solid-solution RuxCu1-xO2 nanocrystals: A promising negative electrode for high-energy-density aqueous hybrid supercapacitors

Xuting Li1, Xiaotang Meng1, Qian Zhang, Jinfeng Sun, Linrui Hou, Changzhou Yuan*   

  1. School of Materials Science & Engineering, University of Jinan, Jinan 250022, China
  • Received:2024-02-02 Revised:2024-04-03 Accepted:2024-05-10 Online:2024-06-04
  • Contact: *E-mail address:. mse_yuancz@ujn.edu.cn (C. Yuan)
  • About author:1These authors contributed equally to this work.

Abstract: The low specific capacitances (SCs) of traditional carbonaceous negative electrodes significantly limit the enhancement in energy density of aqueous hybrid supercapacitors (AHCs). It is still hugely challengeable to explore a candidate with large SCs, which can stably operate in the negative potential region meanwhile. For this propose, we design and fabricate solid-solution RuxCu1-xO2 nanocrystals (NCs), which exhibit competitive SCs and electrochemical stability within the potential range from-0.9 V to 0.0 V in the aqueous KOH electrolyte. The incorporation of Cu enhances the electrochemical utilization of RuO2, reaction kinetics, electronic conductivity, and hydrogen evolution overpotentials, which are all highly dependent upon the added contents of Cu species. The optimized Ru0.8Cu0.2O2 (RuCu82) electrode of a high mass loading of 5 mg cm-2 reveals the best electrochemical capacitances in terms of reversible SCs and capacitance degradation at room temperature and-20 °C. Furthermore, the reversible K+-(de)intercalation induced pseudocapacitance is proposed for electrochemical charge storage process of RuCu82. In particular, remarkable specific energy of 59.1 Wh kg-1 at 400 W kg-1 and excellent cycling stability are achieved in the assembled NiCoO2// RuCu82 AHCs. Our contribution here presents a new promising negative electrode platform with high SCs and electrochemical stability for next-generation AHCs.

Key words: Aqueous hybrid supercapacitors, Negative electrodes, Solid-solution Ru0.8 Cu0.2 O2, Faradaic redox reaction, High energy density