In-Situ-Grown Mg(OH)₂-Derived Hybrid α-Ni(OH)₂ for Highly Stable Supercapacitor

Abstract

EXPERIMENTAL SECTION Synthesis of Mg(OH) 2 slurry. Commercial MgO (A. R.) was calcined at 973 K and then mixed with water according to the mass ratio of 1:10 (MgO/H 2 O) under vigorous stirring for 24 h. After stirring, a slurry of Mg(OH) 2 was obtained and the morphology of the prepared Mg(OH) 2 was confirmed by transmission electron microscopy (TEM) shown in Figure S1 in supporting information. Growth of Mg-Ni(OH) 2 on nickel foam. Typically, the prepared Mg(OH) 2 slurry was coated onto nickel foam (1 cm × 2 cm) and then dried at 373 K for 12 h. The obtained Mg(OH) 2 /nickel foam was pressed at 10.0 M Pa and immersed in 0.5 M Ni(NO 3 ) 2 solution for 48 h at room temperature. After ion-exchange reaction, the obtained Ni(OH) 2 /nickel foam was washed for 5 min under sonication to remove the weakly attached products on the surface before drying at 373 K overnight. The nickel hydroxide obtained by the ion-exchange reaction was denoted as Mg-Ni(OH) 2 . Synthesis of dopant-free Ni(OH) 2 . The dopant-free Ni(OH) 2 was synthesized by hydrothermal method with hexamethylenetetramine (HMA) as precipitation reagent.Typically, 1.45 g nickel nitrate and 0.7 g HMA were dissolved in 35 ml water and then

One‐Step Solvothermal Synthesis of 3D Hierarchical NixCo9‐xS8 Structures for High‐Performance Supercapacitors

“…As we can see from this graph, Ni x Co 9‐x S 8 and P‐Ni x Co 9‐x S 8 electrodes still remained about 69.03 % and 78.83 % of the highest values, indicating a potential application of P‐Ni x Co 9‐x S 8 in high‐rate pseudocapacitors. This can be ascribed to the 3D hierarchical structures with high specific surface area, which is beneficial for the fast transfer of electrons, leading to high specific capacitance and good rate performance ,…”

Metal Oxide and Hydroxide–Based Aqueous Supercapacitors: From Charge Storage Mechanisms and Functional Electrode Engineering to Need‐Tailored Devices

“…[76] The spontaneous ion-exchange reaction, due to differences in the solubility product of Mg(OH) 2 and Ni(OH) 2 , led to simultaneous formation of Ni(OH) 2 and doping with Mg. Mg-doped α-Ni(OH) 2 displayed high Brunauer-Emmett-Teller surface area (202 m 2 g −1 ) and pore volume of 0.56 cm 3 g −1 , which resulted in high specific capacity values: 1931 and 1496 F g −1 at 0.5 to 20 A g −1 in 6 m KOH, respectively. [76] The spontaneous ion-exchange reaction, due to differences in the solubility product of Mg(OH) 2 and Ni(OH) 2 , led to simultaneous formation of Ni(OH) 2 and doping with Mg. Mg-doped α-Ni(OH) 2 displayed high Brunauer-Emmett-Teller surface area (202 m 2 g −1 ) and pore volume of 0.56 cm 3 g −1 , which resulted in high specific capacity values: 1931 and 1496 F g −1 at 0.5 to 20 A g −1 in 6 m KOH, respectively.…”

“…Nevertheless, the specific capacitance decreased quickly after 200 cycles to 47.7% of the initial capacitance due to chemical dissolution of V 3+ Adv. [76] Copyright 2016, American Chemical Society. 2019, 6, 1801797 2 for 3000 charge-discharge cycles and Mg-doped Ni(OH) 2 for 10 000 charge-discharge cycles at 10 A g −1 ; inset shows cyclic voltammograms of Mg-doped Ni(OH) 2 after 1st, 5000th, and 10 000th cycles.…”

“…For example, N-doped graphene||NiO, [50] reduced graphene oxide||Co x Ni 1−x O-reduced graphene oxide, [112] activated carbon nanorod||NiCo 2 O 4 , [113] activated carbon||NiMoO 4 , [114] activated carbon||Mg-doped α-Ni(OH) 2 , [76] activated carbon||Ni-Co hydroxide-N-doped carbon, [100] and carbon nanofoam paper (CNFP)||Ni x Co 1−x (OH) 2 -CNFP cells have been proposed. For example, N-doped graphene||NiO, [50] reduced graphene oxide||Co x Ni 1−x O-reduced graphene oxide, [112] activated carbon nanorod||NiCo 2 O 4 , [113] activated carbon||NiMoO 4 , [114] activated carbon||Mg-doped α-Ni(OH) 2 , [76] activated carbon||Ni-Co hydroxide-N-doped carbon, [100] and carbon nanofoam paper (CNFP)||Ni x Co 1−x (OH) 2 -CNFP cells have been proposed.…”

Optimizing the Supercapacitive Performance and Cyclability of Ni(OH)2 by Combining with CuO Concomitant with Mutual Doping

“…In our recent work, the Mn 3 O 4 /Ni(OH) 2 nanocomposite (assigned to MnNi‐3) synthesized by water‐boiling treatment denoted a high pseudocapacitance and rate property (742 and 318 F g −1 at 1 and 8 A g −1 , respectively) but still with unsatisfactory cyclic stability. The hybrid Ni(OH) 2 fabricated by in situ ion‐exchange reaction with Mg(OH) 2 revealed 95 % retention after 10000 cycles . The Ni−Co nanosheet prepared by hydrothermal treatment delivered a capacitance of 960 F g −1 at 50 A g −1 .…”