In situ grown Na+-doped NH4V4O10 nano-arrays on carbon cloth with ultra-high specific capacity for high-performance aqueous ammonium ion hybrid supercapacitors†

Abstract

Aqueous ammonium ion hybrid supercapacitors (A-HSCs) have sparked significant interest due to their safety, sustainability, and low cost. However, the quest for superior electrode materials for storing ammonium ions still encounters many challenges. Since layered vanadium-based materials usually have a high theoretical capacity and open crystal structure, and the introduction of sodium ions can enhance ionic bonds and cycle stability, this work reports a Na⁺-doped NH₄V₄O₁₀ nano-array grown in situ on carbon cloth through a hydrothermal approach (NaNVO@CC), which serves as a novel cathode material for A-HSCs. The irreversible deammoniation reaction of NH₄V₄O₁₀ was effectively inhibited due to the growth on the carbon cloth and the synergistic effect of Na⁺. Thanks to these advantages, the NaNVO@CC cathode demonstrates outstanding electrochemical performance, achieving an ultra-high specific capacity of 712 F g⁻¹ at 0.50 A g⁻¹ and exceptional cycle stability, retaining 71.1% of its capacitance at 5.00 A g⁻¹ over 20 000 cycles. The built A-HSC exhibits significant power density (8556.6 W kg⁻¹), energy density (77.7 W h kg⁻¹) and superior cycle life. This work proves the enormous potential of doping in enhancing electrode performance, which will offer insights for the creation of high-performance A-HSCs.