Co3O4/NiO/C composites derived from zeolitic imidazolate frameworks (ZIFs) as high-performance anode materials for Li-ion batteries

Hybridization of layered double hydroxides with functional particles

Layered double hydroxides (LDHs) are a class of materials with useful properties associated with their anion exchange abilities as well as redox and adsorptive properties for a wide range of applications including adsorbents, catalysts and their supports, electrodes, pigments, ceramic precursors, and drug carriers. In order to satisfy the requirements for each application as well as to find alternative applications, the preparation of LDHs with the desired composition and particle morphology and post-synthetic modification by the host-guest interactions have been examined. In addition, the hybridization of LDHs with various functional particles has been reported to design materials of modified, improved, and multiple functions. In the present article, the preparation, the heterostructure and the application of hybrids containing LDHs as the main component are overviewed.

Porous Co3O4/NiO@C Chains Assembled from Nanosheets with Excellent Lithium Storage Performance

Carbon layers-coated porous Co3O4/NiO (denoted as PCNO@C) chains are synthesized by the facile solvothermal method and subsequently annealing treatment under an Ar atmosphere, which are assembled from numerous Co3O4/NiO nanosheets. Benefiting from the unique porous chain structure, the volume change of the electrode is greatly relieved during the long-term cycling processes, and then an excellent cycling stability is obtained (the reversible specific capacity of the 1000th cycle can reach 637.3 mA h g-1 at 5000 mA g-1). Besides, a continuous conductive network is constructed by the coated carbon layers and long chains, the movement rate of electrons is effectively accelerated, and the high rate capability is obtained (the high reversible specific capacity of 480.6 mA h g-1 is retained at 10,000 mA g-1). This work contributes a new idea to construct porous chain structure anode materials.

Formation of Carbon-Incorporated NiO@Co3O4 Nanostructures via a Direct Calcination Method and Their Application as Battery-Type Electrodes for Hybrid Supercapacitors

Nickel and cobalt oxides are promising electrode materials for supercapacitors, but their poor conductivity and sluggish kinetics seriously hinder their application. Herein, a simple one-step calcination method was proposed to prepare carbon-incorporated NiO@Co₃O₄ (denoted as CNC) using a NiCo Prussian blue analogue (NiCo-PBA) as a precursor. The effect of calcination temperature on the electrochemical behavior of CNC was investigated. Benefiting from the relatively large specific surface area and porous structure characteristics, when used as an electrode for supercapacitors, the CNC obtained at 400 °C shows the typical features of a battery-type electrode, with a good specific capacitance of 208.5 F g^-1 at 1 A g^-1 and a rate capability of 70.8% at 30 A g^-1. The hybrid supercapacitor (HSC) constructed with the optimum CNC electrode can provide a high energy density of 32.6 Wh kg^-1 at the corresponding power density of 750.0 W kg^-1 and an excellent cycling stability of 87.1% over 5000 cycles. This study provides a simple calcination method for preparing MOF-derived high-conductivity mixed metal oxide electrode materials for supercapacitors.

Sandwich shelled TiO2@Co3O4@Co3O4/C hollow spheres as anode materials for lithium ion batteries

A sandwich shelled hollow TiO₂@Co₃O₄@Co₃O₄/C composite is synthesized by consecutive coating of Co₃O₄ nanosheets and TiO₂ particles on Co₃O₄/C hollow spheres. The composite delivers an excellent lithium storage performance, maintaining 1081.78 mA h g^-1 after 100 cycles at 0.2 A g^-1 and 772.23 mA h g^-1 after 300 cycles at 1 A g^-1, due to its superior structure combining the advantages of each component with favorable electron-transfer, Li⁺-diffusion properties, and distinguished stability.