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• A high-performance nickel electrode integrated with Co and carbon dots (CD-Co/Ni(OH) 2) has been prepared by cathodic electrodeposition. • The introduction of Co greatly improves the stability of the Ni(OH) 2 electrode, particularly at high current density. • The CDs-Co/Ni(OH) 2 electrode presents a high specific capacitance and an excellent capacitance retention. • The Ni/Zn supercapattery assembled with a zinc flake as negative electrode and a CDs-Co/Ni(OH) 2 electrode as positive electrode exhibits high power density, high energy density and remarkable cycling stability. Nickel hydroxide (Ni(OH) 2) is one of the most valuable electrode materials for supercapacitors. Owing to the low stability and conductivity of Ni(OH) 2 electrode, the preparation of a fast and high-stability Ni(OH) 2 electrode is a significant challenge. Nickel hydroxide integrated with cobalt and carbon dots (CDs-Co/Ni(OH) 2) as a high performance electrode has been prepared by cathodic electrodeposition for supercapattery in this work. Compared with unintegrated Ni(OH) 2 electrode or carbon dots integrated Ni(OH) 2 electrode, the introduction of Co greatly improves the stability of the Ni(OH) 2 electrode, particularly at high current density. The as-obtained CDs-Co/Ni(OH) 2 electrode presents a high specific capacitance of 338.6 mAh/g at 5 A/g and an extraordinary cycling stability with 1000 cycles even under a high current density of 40 A/g (retaining 84.6%). Besides, the CDs-Co/Ni(OH) 2 electrode exhibits an energy density of 281.2 Wh/kg at a power density of 57.2 kW/kg. Such a glorious stable CDs-Co/Ni(OH) 2 electrode may provide significant insight into future multifarious electronics and electrified vehicle applications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, α-Ni(OH) 2 with controllable pristine crystal size is directly electrodeposited on a substrate of Ti wire mesh to fabricate the integrated electrode. The nanoscale effects on morphology, microstructure and electrochemical performance of the cathodic deposited α-Ni(OH) 2 are studied. The results show that the morphology of α-Ni(OH) 2 varies from irregular honeycomb-like nanopieces, ball-shaped particles to oval nanoplates as the cathodic deposition current density increases. The nanostructure diversity of the cathodic deposited α-Ni(OH) 2 is due to the different nanosize which directly depends on the cathodic deposition current density. The electrochemical performances of the cathodic deposited α-Ni(OH) 2 increase with the decrease of the pristine crystal size of α-Ni(OH) 2 . The oval α-Ni(OH) 2 nanoplates consisting of nanosheets with a pristine crystal size of 3 ∼ 5 nm × 5 ∼ 7 nm show the ultrahigh specific capacities of ∼348 mAh g −1 and ∼312.5 mAh g −1 at charge/discharge current density of 5 A g −1 and 100 A g −1 , respectively, and over 70% specific capacity still remains after 1000 cycles, while the irregular honeycomb-like α-Ni(OH) 2 consisting of nanosheet with a pristine crystal size of 10 ∼ 15 nm × 15 ∼ 20 nm shows only ∼260 mAh g −1 specific capacity at 5 A g −1 and ∼150 mAh g −1 at 100 A g −1 . The ultrahigh electrochemical performances are attributed to the nanoscale and the defective nanostructure of the cathodic deposited α-Ni(OH) 2 . [ABSTRACT FROM AUTHOR]

In this work, we successfully synthesized Ni(OH) 2 thin film electrode in situ doped with CNTs/rGO by cathodic electrodeposition on titanium mesh. The doping effects of CNTs and/or rGO, and the technical conditions, are investigated. The doping of CNTs/rGO can greatly improve the electrochemical performance by forming the porous structure and the conductive network in the Ni(OH) 2 thin film. The highest capacity, 429.5 mAh/g at a current density of 5 A/g, is achieved for the electrode with 0.24 mg/cm2 Ni(OH) 2 and codoped with CNTs and rGO, as compared with only 323.9 mAh/g for undoped electrode. Even at 100 A/g, the specific capacity can still remain 347.5 mAh/g (vs. 221.5 mAh/g for the undoped electrode), and after 1000 cycles, the retention rate of the specific capacity is 74.9% as compared with only 42.7% for the undoped electrode. Even with higher loading amounts of 1.92 mg/cm2 Ni(OH) 2 , the specific capacity retention rate of the codoped electrode is still much higher than that of the undoped electrode. The high electrochemical performance can be attributed to the better ion/electron transfer ability of the codoped electrode. In conclusion, by the cathodic electrodeposition and in situ doping of CNTs/rGO, the porous structure and the conductive network in Ni(OH) 2 film can be constructed, which can improve the ion/electron transfer ability, therefore, the high performance film electrode with higher loading amount of Ni(OH) 2 can be prepared. [ABSTRACT FROM AUTHOR]