High-performance flexible hybrid supercapacitor based on NiAl layered double hydroxide as a positive electrode and nitrogen-doped reduced graphene oxide as a negative electrode

Facile Assembly of Hybrid Micro-Supercapacitors for a Sunlight-Powered Energy Storage System

Herein, hybrid micro-supercapacitors (MSCs), consisting of positive CoNi layer double hydroxides (LDHs) decorated on carbon nanotubes (CoNi LDHs@CNTs) and negative CNT electrodes, were assembled by facile drop-coated and electrodeposition methods. The as-fabricated MSCs were optimized in view of electrochemical performance, and the CoNi LDHs-2@CNTs//CNT MSC exhibited a favorable performance and was thus chosen to be the candidate for MSC device package. The packaged CoNi LDHs-2@CNTs//CNT MSC demonstrated a large areal capacitance of 11.0 mF·cm^-2 at a current density of 0.08 mA·cm^-2, a good rate performance (56% areal capacitance retained at a higher current density of 0.4 mA·cm^-2), and a favorable cycling stability and reversibility (92% of the original areal capacitance was retained after 5000 cycles). Furthermore, the MSC device recorded an energy density of 1.5 μWh·cm^-2 at a power density of 42.5 μW·cm^-2 and was successfully applied for the storage of energy supplied by solar cells to operate a red light-emitting diode. All these findings demonstrated the promising practical energy storage application of the as-fabricated hybrid MSC devices in the construction of sunlight-powered energy storage systems.

NiAlP@Cobalt substituted nickel carbonate hydroxide heterostructure engineered for enhanced supercapacitor performance

Transitional metal phosphides with high electrical conductivity and superb physicochemical features have been recognized as ideal battery-type electrode materials for outstanding performance supercapacitors. However, their specific capacities and structural stability are needed to be enhanced for large-scale practical applications. To overcome these shortcomings, we fabricated heterostructured NiAlP@cobalt substituted nickel carbonate hydroxide (Co-NiCH) nanosheet arrays by sequential a hydrothermal reaction, a phosphorization treatment, and a second hydrothermal reaction. Profiting from its core-shell porous nanostructure and synergistic effect of NiAlP with high electrical conductivity and Co-NiCH with high redox reactivity, the resultant NiAlP@Co-NiCH electrode delivers a large specific capacity of 825.7C g^-1 at 1 A g^-1, excellent rate capability with 78.9% capacity retention and long lifespan, superior to those of pure NiAlP and Co-NiCH electrodes. Additionally, an aqueous asymmetric supercapacitor device is constructed by NiAlP@Co-NiCH and lotus pollen-derived hierarchical porous carbon, which demonstrates a large energy density of 82.3 Wh kg^-1 at a power density of 739.8 W kg^-1, and wonderful cycle stability with 88.2% capacity retention after 10,000 cycles. This work proposes a feasible strategy on construction of transitional metal phosphide-based heterojunctions for advanced asymmetric supercapacitor devices.