In situ cascade steric stabilization of poly(ionic liquid) mediated hexagonal nickel hydroxide morphogenesis for high-performance flexible supercapacitors

Abstract

A hybrid material comprising nickel hydroxide (Ni(OH)₂) enveloped in a poly(ionic liquid) (PIL-Br), poly(1-butyl-3-vinylimidazolium bromide), is effectively employed as an additive in this study, wherein PIL-Br provides precise control over the shape and arrangement of Ni(OH)₂ crystals. The PIL can chemically couple with the as-synthesized Ni(OH)₂, imparting a modified surface electronic structure. This innovation introduces a fresh perspective for energy storage applications. Extensive characterization, along with density functional theory calculations, has explored the impact of PIL polymer groups. The findings indicate that these polymers facilitate a more favourable redox response on the surface of Ni(OH)₂. The desired morphology of the nanoarchitectonics leads to a high performing solid-state free-standing device with 245 F g⁻¹ specific capacitance at 1 A g⁻¹. When integrated with an activated carbon electrode and a unique polyvinyl 1-butyl-3-methylimidazolium tetrafluoroborate/polyvinyl alcohol (BMIMBF₄/PVA) configuration, the hybrid device achieves an ED of 86.2 W h kg⁻¹ at a PD of 800 W kg⁻¹. Profoundly, it retains a capacity retention of 96% even after undergoing 10 000 cycles at 5 A g⁻¹. The utilization of stabilized nanoarchitectonics incorporating redox-active polymers marks a novel direction in various energy applications.