Search

• NiGa-LDHis firstly synthesized by simple hydrothermal method. • Ni 2 P and NiGa 2 O 4 are grown in situ on the NiGa-LDH by selectivephosphating. • DFT calculations confirm positive effect of phosphating on the conductivity of NiGa-LDH. • The Ni 2 P/NiGa 2 O 4 -1.2/NiGa-LDH/NF//Co 3 O 4 -C(72Wh kg-1) can light multiple LEDs in parallel. Layered double hydroxides (LDHs) materials are ideal electrode materials for supercapacitors (SCs) due to their high capacitance, large surface area and fast redox reaction. However, the limited reaction site of LDHs is one of the main obstacles to increasing the capacitance of SCs. Here, NiGa-LDH grown on nickel foam (NF) by one-step hydrothermal method is derived into Ni 2 P/NiGa 2 O 4 /NiGa-LDH/NF by partial phosphating method induced by NaH 2 PO 2. Ni 0.5 Ga 0.5 -LDH/NF has good electrochemical performance, and the capacitance can reach 295 mAh g−1 (2124F g−1) when the current density is 1 A g−1. Significantly, Ni 2 P/NiGa 2 O 4 /NiGa-LDH/NF well preserves the layered structure of LDHs, inherits the low transfer impedance of interlayer ions, and can greatly reduce the thickness of the nanosheets, exposing more active sites and speeding up the electron transfer speed. According to the first principle calculation, Ni 2 P and NiGa 2 O 4 formed by phosphating helps to increase the free electron ratio in Ni 2 P/NiGa 2 O 4 /NiGa-LDH/NF, thus improving the charge transfer behavior in electrochemical reactions. The material can provide an ultra-high electrochemical capacity of 454.7 mAh g−1 (3274F g−1) at 1 A g−1. In addition, a hybrid supercapacitors (HSCs) is prepared by coupling the Co 3 O 4 -C as negative electrode with the high capacitance Ni 2 P/NiGa 2 O 4 /NiGa-LDH/NF as positive electrode. Ni 2 P/NiGa 2 O 4 /NiGa-LDH/NF // Co 3 O 4 -C HSCs provides the energy density of 72 Wh kg−1 at the power density of 800 W kg−1 with excellent long-term stability up to 8000 cycles, and is expected to be used in next-generation energy storage systems. [ABSTRACT FROM AUTHOR]

• The ternary metal NiCoGa-LDHs is firstly synthesized by simple hydrothermal method. • The morphology, crystal structure stability and capacitance of NiCoGa-LDHs are systematically studied. • The Ni 1 Co 3 Ga 1 -LDHs@CC electrode exhibits excellent capacitance of 2012.5 F g-1 at 1 A g-1. • The asymmetric supercapacitor (84.22 Wh kg-1) can light multiple LEDs in parallel. Ternary metal layered double hydroxides (LDHs) have been widely used in supercapacitors (SCs) due to their polyvalent state and high electrochemical activity. In this study, Ga (III) doped NiCo layered double hydroxides (NiCoGa-LDHs) electrode material is prepared on carbon cloth (CC) by simple one-step hydrothermal method for the first time. The effects of Ga3+ with different molar ratios on the structure, morphology, crystallinity, ion transport mechanics and electrochemical properties of ternary LDHs electrode materials are systematically investigated. At Ga3+ = 1.0, the as-synthesized Ni 1 Co 3 Ga 1 -LDHs@CC exhibits a special electrochemical capacitance of 2012.5 F g-1 at 1 A g-1 with 57.7% capacitance retention observed at 5.0 A g-1. The synthesis and evaluation of the two bimetallic NiCo-LDHs and NiGa-LDHs are similar in order to demonstrate the performance improvement of gallium heterovalent substitution. And heterovalent substitution of gallium for cobalt ion and nickel ion is proved indirectly. An Asymmetric supercapacitors (ASCs) device is assembled with Ni 1 Co 3 Ga 1 -LDHs@CC as anode and mesoporous carbon (MPC) as cathode, providing a high energy density of 84.22 Wh kg-1 at a power density of 800.1 W kg-1, with excellent cyclic stability. This study provides a new way to improve the electrochemical performance and stability of ternary metal LDHs. [ABSTRACT FROM AUTHOR]

Abstract Supercapacitor is a new energy storage device between traditional capacitor and rechargeable battery. Not only has the characteristics of fast charging and discharging of capacitor, but also has the characteristics of energy storage of battery. The electrochemical tests indicate that the electrode in view of porous Ni 2 P 2 O 7 nanowires (NWs) has a specific capacitance of 772.5 Fg-1 at current density 1 Ag-1. Furthermore, porous Ni 2 P 2 O 7 NWs have been successfully applied to construct all-solid hybrid supercapacitors. Carbon nanotubes (CNT) and easily treated nickel pyrophosphate (Ni 2 P 2 O 7) are considered as electrode materials for supercapacitors under alkaline conditions. The equipment has a high energy density of 6.25 mWh cm−2 and good cycle stability of 94% capacitance retention after 3000 cycles, which identifies that porous Ni 2 P 2 O 7 nanowires are promising supercapacitor active materials. Highlights • A novel intercalated porous Ni 2 P 2 O 7 nanowires was prepared by simple chemical precipitation method. • The intercalated porous Ni 2 P 2 O 7 nanowires as new electrode materials exhibited great electrochemical properties. • Ni 2 P 2 O 7 //CNT ASC device is a promising material for fiber supercapacitors and electronic applications. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are a promising positive electrode material for super-capacitors (SCs) due to multiple oxidation reduction states. However, the structure of LDH is prone to collapse during the redox reaction and has low conductivity, which further hinders the improvement of capacity performance. Here in, nitrogen-doped graphene quantum dot (N-GQD) is assembled on nickel gallium layered double hydroxide (NiGa-LDH) derived from two-dimension nickel metal organic frameworks (Ni-MOF) on nickel foam (NF) to prepare stable interlaced nano-sheets hybrid structures. As a result of the above synergies, the NiGa-LDH/N-GQD/NF electrode has a high specific capacitance of 2160 F g−1 at 1 A g−1 and good cycling stability with a capacity retention rate of 87.5% in 5000 cycles. In addition, we also make ASC device using NiGa-LDH/N-GQD/NF and Carbon NSs as positive/negative electrodes. The energy density of the assembled ASC device is 78.8 Wh kg−1 at power density of 1432.7 W kg−1, while the capacitance retention after 8000 cycles reaches 81.2%. Meanwhile, individually assembled ASC device can power multiple LEDs in parallel. This work provides an effective way to construct new electrode materials with high energy storage density, good cycling performance and power density by assembling quantum dots into LDH nano-sheets derived from MOF through reasonable design. The NiGa-LDH/N-GQD electrode material prepared on nickel foam has good capacity and cycling stability due to the synergistic effect of interleave NiGa-LDH nano-sheet derived from Ni-MOF and N-GQD embedded in it. [Display omitted] • NiGa-LDH/N-GQD/NF is firstly synthesized by simple hydrothermal method. • The NiGa-LDH derived from the Ni-MOF prepared on nickel foam with interleaved nano-sheet hybrid structure have large specific surface area and can provide more reaction sites. • The introduction of N-GQD plays an important role in improving the electrical conductivity and surface wettability of electrodes. • The NiGa-LDH/N-GQD-2/NF//Carbon NSs asymmetric supercapacitors device (78.8 Wh kg−1) can light multiple LEDs in parallel. [ABSTRACT FROM AUTHOR]

• A novel intercalated Co 3 O 4 -C/Ni 2 P 2 O 7 was prepared by simple chemical precipitation method. • The intercalated Co 3 O 4 -C/Ni 2 P 2 O 7 as new electrode materials exhibited great electrochemical properties. • Co 3 O 4 -C/Ni 2 P 2 O 7 products are ideal electrode materials for supercapacitors. Nickel pyrophosphate (Ni 2 P 2 O 7) is considered as a potential next-generation electrode material for supercapacitors. Here, we report a new type of cathode material for supercapacitors in, which consists of rhombic dodecahedron Co 3 O 4 -C growing on two-dimensional (2D) Ni 2 P 2 O 7 nanosheets. Surprisingly, Co 3 O 4 -C/Ni 2 P 2 O 7 materials exhibit bright electrochemical properties with a relatively high specific capacitance of 2537.78 Fg−1 and remarkable cyclic stability (88.5% after 3000 cycles). Therefore, the prepared Co 3 O 4 -C/Ni 2 P 2 O 7 electrode material is a significant candidate material for supercapacitors. The synthesis process is simple, low cost and environmentally friendly. Notably, Co 3 O 4 -C/Ni 2 P 2 O 7 products have excellent electrochemical properties and are candidate electrode materials for supercapacitors. The Co 3 O 4 -C/Ni 2 P 2 O 7 products have excellent electrochemical properties, which indicate the Co 3 O 4 -C/Ni 2 P 2 O 7 materials imply their promising potential applications in the energy storage. Most importantly, this work provides a scalable strategy for morphology-controlled synthesis of metal oxides by recrystallization. [ABSTRACT FROM AUTHOR]