Hydrogen bond stabilized β-Ni(OH)x–SO4 interlaminar materials for highly active supercapacitors

Abstract

To improve the intrinsic property of Ni(OH)₂ for advanced supercapacitors, structural and valence engineering are combined here to prepare porous β-Ni(OH)_x–SO₄ (NSO) interlaminar materials. NSO has an expanded interplanar spacing and in-plane porous channels, thus offering a 3D accessible structure for the charging and discharging process. The intercalation of SO₄²⁻ can retain the layer spacing of NSO through hydrogen bond during the charge transport and effectively drive electrons close to the Fermi level of NSO, which significantly enhances the stability and conductivity of the sample. The rigid interlayer space and in-plane channels enable NSO to exhibit a high specific capacity of 212.5 mA h g⁻¹ at 3 A g⁻¹. The assembled asymmetric supercapacitor device shows a high energy density of 41.2 W h kg⁻¹ at 796.9 W kg⁻¹ and maintains 86.8% capacity retention after 10 000 cycles at 4 A g⁻¹.