Hydrothermal Synthesis of CuBi₂O₄ Nanosheets as Electrodes for Enhanced Performance in Aqueous Zn-Ion Battery and Supercapacitor

Aqueous zinc-ion batteries (AZIBs) and supercapacitors (SCs) have wide application prospects in the field of energy storage device due to high-safety, low cost, and environmental friendliness. However, their large-scale application is hampered by the lack of suitable electrode materials. In this work, the smooth CuBi₂O₄ nanosheets with thickness of about 4–5.5 nm have been prepared by a simple one-step hydrothermal method, and are reported as electrode materials of these two types of devices. Encouragingly, the as-prepared CuBi₂O₄ nanosheets exhibit fast electronic/ion diffusion, good reversibility and high pseudo-capacitance for AZIBs and SCs. For the AZIBs, CuBi₂O₄ nanosheets endows high capacity of 186 mAh g⁻¹ after a long-term stability of 800 cycles, Zn storage mechanism is also discussed. For the SCs, it delivers 666.7 F g⁻¹ at 10 A g⁻¹, with 95.8 pct capacitance retention after 7000 cycles. The result suggests a prospect use as electrode material for advanced AZIBs and SCs.