Facile synthesis of Pr-doped Co3O4 nanoflakes on the nickel-foam for high performance supercapacitors

Electrode Materials, Structural Design, and Storage Mechanisms in Hybrid Supercapacitors

Currently, energy storage systems are of great importance in daily life due to our dependence on portable electronic devices and hybrid electric vehicles. Among these energy storage systems, hybrid supercapacitor devices, constructed from a battery-type positive electrode and a capacitor-type negative electrode, have attracted widespread interest due to their potential applications. In general, they have a high energy density, a long cycling life, high safety, and environmental friendliness. This review first addresses the recent developments in state-of-the-art electrode materials, the structural design of electrodes, and the optimization of electrode performance. Then we summarize the possible classification of hybrid supercapacitor devices, and their potential applications. Finally, the fundamental theoretical aspects, charge-storage mechanism, and future developing trends are discussed. This review is intended to provide future research directions for the next generation of high-performance energy storage devices.

Zeolitic Imidazolate Framework 67-Derived Ce-Doped CoP@N-Doped Carbon Hollow Polyhedron as High-Performance Anodes for Lithium-Ion Batteries

Zeolitic Imidazolate Framework 67 (ZIF-67) and its derivates have attracted extensive interest for lithium-ion batteries (LIBs). Here, Cerium-doped cobalt phosphide@nitrogen-doped carbon (Ce-doped CoP@NC) with hollow polyhedron structure materials were successfully synthesized via ionic-exchange with Co and Ce ions using the ZIF-67 as a template followed with a facile low-temperature phosphorization treatment. Benefitting from the well-designed hollow polyhedron, steady carbon network, and Ce-doping structural merits, the as-synthesized Ce-doped CoP@NC electrode demonstrated superior performance as the anode in LIBs: a superior cyclability (400 mA h g−1 after 500 cycles) and outstanding rate-capability (590 mA h g−1, reverted to 100 mA g−1). These features not only produced more lithium-active sites for LIBs anode and a shorter Li-ion diffusion pathway to expedite the charge transfer, but also the better tolerance against volume variation of CoP during the repeated lithiation/delithiation process and greater electronic conductivity properties. These results provide a methodology for the design of well-organized ZIFs and rare earth element-doped transition metal phosphate with a hollow polyhedron structure.

Fabrication of honeycomb-structured composite material of Pr2O3, Co3O4, and graphene on nickel foam for high-stability supercapacitors

The Pr2O3/Co3O4/rGO/NF electrode has been prepared by hydrothermal method and annealing process, with high specific capacitance and excellent cycle stability.