Pseudo-solid-solution CuCo2O4/C nanofibers as excellent anodes for lithium ion batteries

CuCo2O4 Hollow Microspheres with Graphene Composite Targeting Superior Lithium-Ion Storage

CuCo₂O₄, a type of promising lithium-ion storage material, exhibits high electrochemical properties in lithium-ion batteries and enormous economic benefits. However, its practical application is limited by problems such as structural collapse and electrochemical stability during the charging and discharging process. In this work, the reduced graphene oxide (rGO)-coated CuCo₂O₄ (CuCo₂O₄/rGO) hollow microspheres were successfully prepared by electrostatic self-assembly. The CuCo₂O₄/rGO electrode shows an outstanding capability for lithium-ion storage and a remarkable rate capacity, e.g., 445 mA h g^-1 at 5 A g^-1. After 150 cycles at 0.1 A g^-1, the reversible capacity of the CuCo₂O₄/rGO electrode is as high as 1080 mA h g^-1, and it can still retain about 530 mA h g^-1 in the 400th cycle at 1 A g^-1. The hollow microspheres with mesoporous shells can cause electrolyte penetration into the spherical shell to effectively shorten the transfer distance of lithium ions, and the encapsulation of graphene improves the conductivity and stability of CuCo₂O₄, which endows CuCo₂O₄/rGO with a wonderful Li⁺ storage performance. It is proved that this is an efficient method to improve the electrochemical performance of metal compounds for better applications in energy storage.

Formation of uniform porous yolk-shell MnCo2O4 microrugby balls with enhanced electrochemical performance for lithium storage and the oxygen evolution reaction

Mixed transition metal oxides with favorable electrochemical properties are promising electrode materials in energy storage and conversion systems. In this work, uniform porous yolk-shell MnCo₂O₄ (denoted as YSM-MCO) microrugby balls have been synthesized by simple annealing treatment of metal carbonates with a microrugby ball shape in air. Benefiting from the desired porous structure and composition, the as-synthesized YSM-MCO exhibits enhanced electrochemical performance when investigated as anode materials for lithium-ion batteries and electrocatalysts for the oxygen evolution reaction. The YSM-MCO demonstrates remarkable lithium storage properties with a good cycling stability (94% capacity retention over 200 cycles at 0.5 A g^-1) and superior rate capability (414 mA h g^-1 at 5 A g^-1). In addition, the YSM-MCO also exhibits better OER activity than most of the reported MnCo₂O₄-based electrocatalysts.

Facile Preparation of Porous Rod-like Cu x Co3-x O4/C Composites via Bimetal-Organic Framework Derivation as Superior Anodes for Lithium-Ion Batteries

To meet growing demand of energy, lithium-ion batteries (LIBs) are under enormous attention. The development of well-designed ternary transition metal oxides with high capacity and high stability is important and challengeable for using as electrode materials for LIBs. Herein, a new and highly reversible carbon-coated Cu-Co bimetal oxide composite material (Cu x Co3-x O4/C) with a one-dimensional (1D) porous rod-like structure was prepared through a bimetal-organic framework (BMOF) template strategy followed by a morphology-inherited annealing treatment. During the annealing process, carbon derived from organic frameworks in situ fully covered the synthesized bimetal oxide nanoparticles, and a large number of porous spaces were generated in the MOF-derived final samples, thus ensuring high electrical conductivity and fast ion diffusion. Benefiting from the synergetic effect of bimetals, the unique 1D porous structure, and conductive carbon network, the as-synthesized Cu x Co3-x O4/C delivers a high capacity retention up to 92.4% after 100 cycles, with a high reversible capacity still maintained at 900 mA h g-1, indicating an excellent cycling stability. Also, a good rate performance is demonstrated. These outstanding electrochemical properties show us a concept of synthesis of MOF-derived bimetal oxides combining both advantages of carbon incorporation and porous structure for progressive lithium-ion batteries.

Reinforcing Germanium Electrode with Polymer Matrix Decoration for Long Cycle Life Rechargeable Lithium Ion Batteries

Germanium is a promising anode material for lithium ion batteries because of its high theoretical specific capacity and low operation voltage. However, a significant challenge in using Ge-based anodes is the large volume variation during cycling that causes pulverization and capacity fade. Despite intense studies in the past decade, unsatisfactory cycling stability of the Ge-based electrodes still impedes their widespread applications. In this study, we demonstrate a high-performance electrode through the synergistic combination of a high-capacity Ge film grown on a three-dimensional current collector and an in situ formed poly(vinylidene fluoride)-hexafluoropropene/SiO₂ protective layer. Specifically, the polymer matrix is in continuous contact with the surface of the Ge shell, which provides improved mechanical and ionic transport properties. As a highlight, we present impressive cycling stability over 3000 cycles at 1 C rate with a capacity retention as high as 95.7%. Furthermore, the LiCoO₂-Ge full battery operates at an average voltage of 3.3 V at 0.5 C and maintains good electrochemical performance, suggesting great potential for applications in energy storage and conversion devices.