High-mass-loading hierarchical CoNiOOH nanosheet arrays for high-energy and durable alkaline zinc-ion hybrid supercapacitors

Alkaline zinc-ion hybrid supercapacitors (A-ZHSs) have emerged as promising aqueous energy storage systems owing to their unique ability to simultaneously deliver high energy and power densities. However, achieving long-term cycling stability and structural integrity under high mass loading and ultrahigh current density remains a straightforward and scalable synthesis strategy was developed to construct hierarchical CoNiOOH nanosheet array microspheres (CoNi‑OOH‑MSs) on activated carbon cloth. Benefiting from the unique layered-network architecture, high mass loading (13.3 mg cm⁻²), and favorable reaction kinetics, the CoNi-OOH-MSs electrode delivered a high capacitance of 16.9 F cm⁻² at 10mA cm⁻². Moreover, the assembled aqueous A-ZHS device delivers a high energy density of 4.225 mWh cm⁻² at a power density of 3.25 mW cm⁻² and retains 81% of its initial capacity after 20,000 cycles at 50 mA cm⁻² (equivalent to 3.85 A g⁻¹). The charge storage mechanism and practical applicability were further verified by electrochemical analyses and flexible device evaluations. These findings demonstrate the superior performance of high-mass-loading CoNiOOH electrodes and establish a practical and broadly applicable design strategy for advanced alkaline zinc-ion hybrid supercapacitors with high energy density, high power capability, and long-term durability. © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.