Activated graphene nanosheets/spinule-like Ni(OH)2 composite as cathode materials for high performance supercapacitors

Rational Design and in-situ Synthesis of Ultra-Thin β-Ni(OH)2 Nanoplates for High Performance All-Solid-State Flexible Supercapacitors

The all-solid-state flexible supercapacitor (AFSC), one of the most flourishing energy storage devices for portable and wearable electronics, attracts substantial attentions due to their high flexibility, compact size, improved safety, and environmental friendliness. Nevertheless, the current AFSCs usually show low energy density, which extremely hinders their practical applications. Herein, ultra-thin β-Ni(OH)₂ nanoplates with thickness of 2.4 ± 0.2 nm are in-situ grown uniformly on Ni foam by one step hydrothermal treatment. Thanks to the ultra-thin nanostructure, β-Ni(OH)₂ nanoplates shows a specific capacitance of 1,452 F g⁻¹ at the scan rate of 3 mV s⁻¹. In addition, the assembled asymmetric AFSC [Ni(OH)₂//Activated carbon] shows a specific capacitance of 198 F g⁻¹. It is worth noting that the energy density of the AFSC can reach 62 Wh kg⁻¹ while keeping a high power density of 1.5 kW kg⁻¹. Furthermore, the fabricated AFSCs exhibit satisfied fatigue behavior and excellent flexibility, and about 82 and 86% of the capacities were retained after 5,000 cycles and folding over 1,500 times, respectively. Two AFSC in series connection can drive the electronic watch and to run stably for 10 min under the bending conditions, showing a great potential for powering portable and wearable electronic devices.

Hierarchical CoO@Ni(OH)2 core-shell heterostructure arrays for advanced asymmetric supercapacitors

Constructing multicomponent electrode materials with a rational structure is an effective route to develop high-performance supercapacitors. We herein report a novel nickel-foam-supported hierarchical CoO@Ni(OH)₂ nanowire-nanosheet core-shell heterostructure array synthesized by a facile hydrothermal-electrodeposition strategy. The core CoO nanowire arrays with good electrical conductivity and shell Ni(OH)₂ nanosheets with thickness of ∼ 2 nm synergistically contributes to increased active sites, fast mass transfer, and improved structural stability. Consequently, the optimal CoO@Ni(OH)₂-400 s architecture delivers a high specific capacitance of 1418.2 F g^-1 at 1 A g^-1 and 93.7% retention after 5000 cycles. Furthermore, the CoO@Ni(OH)₂//activated carbon asymmetric supercapacitor could achieve an outstanding energy density of up to 92.47 W h kg^-1 at 800 W kg^-1. This simple but effective strategy provides insight into the development of core-shell hierarchical architectures for constructing high-performance supercapacitors.

Hierarchical Co-doped SnS2@Ni(OH)2 double-shell crystalline structure on carbon cloth with gradient pore distribution for superior capacitance

Hierarchical Co-doped SnS₂@Ni(OH)₂ double-shell nanosheet arrays are coated on carbon cloth, the vertically aligned arrays with gradient pore distribution can facilitate the charge/ion transfer rate, thus improve the energy storage performance.

Co(OH)F nanorods@K x MnO2 nanosheet core-shell structured arrays for pseudocapacitor application

In this work, Co(OH)F nanorods@K x MnO2 nanosheet core-shell nanostructure was assembled on Ni foam by a facile hydrothermal method and incorporated with an electrodeposition process. Benefiting from their core-shell nanostructure and heterogeneous nanocomposites, the arrays present high areal capacitance up to 1046 mF cm-2 at 1 mA cm-2 and display a remarkable specific capacitance retention of 118% after 3000 cycles. When the current density increases to 10 mA cm-2, the capacitance is 821 mF cm-2 displaying a good rate capability. The excellent electrochemical properties allow them to be used as a promising electrode material for pseudocapacitors and display wide application potential in the field of electrochemical capacitors.