Structurally Stable Ni(OH)2 Composite with Super Long-term Cycling Life for Aqueous High-performance Supercapacitor

We synthesized an electrochemical structurally stable composite electrode, containing Ni-doped Co(CO3)0.5OH ⋅ 0.11H2O nanoneedles and nanoflake-/nanofrustum-like Ni(OH)2 with highly hydrophilic group, leading to enhanced rare performance. The electrode exhibits an outstanding ultra-long cycle life of more than 140,000 cycles. Specially, the assembled aqueous hybrid supercapacitor presents more than 80 % capacity retention even after 170,000 cycles and high energy density of 44.5 Wh kg−1. This work highlights a feasible strategy to design and develop high-efficiency electrodes via engineering on composition and nanostructure.