Facile Fabrication of Hierarchical Manganese-Cobalt Mixed Oxide Microspheres as High-Performance Anode Material for Lithium Storage

The Review of Hybridization of Transition Metal-Based Chalcogenides for Lithium-Ion Battery Anodes

Transition metal chalcogenides as potential anodes for lithium-ion batteries have been widely investigated. For practical application, the drawbacks of low conductivity and volume expansion should be further overcome. Besides the two conventional methods of nanostructure design and the doping of carbon-based materials, the component hybridization of transition metal-based chalcogenides can effectively enhance the electrochemical performance owing to the synergetic effect. Hybridization could promote the advantages of each chalcogenide and suppress the disadvantages of each chalcogenide to some extent. In this review, we focus on the four different types of component hybridization and the excellent electrochemical performance that originated from hybridization. The exciting problems of hybridization and the possibility of studying structural hybridization were also discussed. The binary and ternary transition metal-based chalcogenides are more promising to be used as future anodes of lithium-ion batteries for their excellent electrochemical performance originating from the synergetic effect.

Phase structure engineering of MnCo2Ox within electrospun carbon nanofibers towards high-performance lithium-ion batteries

Metal oxides are prospective alternative anode materials to the commercial graphite for lithium ion batteries (LIBs), while their practical application is seriously hampered by their poor conductivities and large volume changes. Herein, we report the controllable synthesis of amorphous/crystalline MnCo₂O_x nanoparticles within porous carbon nanofibers (marked as MCO@CNFs) through a facile electrospinning strategy and subsequent annealing reactions. The phase structures from Co/MnO_X to amorphous MnCo₂O_x and crystalline MnCo₂O_4.5 can be readily tuned by thermal reduction/oxidation under controlled atmosphere and temperature. When examined as anode for LIBs, the optimized MCO@CNFs delivers a high stable capacity of 780.3 mA h g^-1 at 200 mA g^-1 after 250 cycles, which is attributed to the synergistic effect of the distinctive amorphous structure and defective carbon nanofiber matrices. Specifically, the amorphous structure with rich defects offers more reactive sites and multiple pathways for the Li⁺ diffusion, while carbon hybridization sufficiently improves the electrode conductivities as well as buffers the volume changes. More importantly, we demonstrate a convenient synthesis strategy to control the metal-to-oxide structure evolution within carbon matrices, which is of great importance in exploring high-performance electrodes for next generation LIBs.

Facile Synthesis of Flower-Like MnCo2 O4 @PANi-rGO: A High-Performance Anode Material for Lithium-Ion Batteries

Flower-like MnCo₂ O₄ was prepared in a self-assembly process and used in the formation of MnCo₂ O₄ @polyaniline (MnCo₂ O₄ @PANi) that proceeds by a simple in situ polymerization. The MnCo₂ O₄ @PANi-reduced graphite oxide (MnCo₂ O₄ @PANi-rGO) composite was then synthesized by introducing rGO into MnCo₂ O₄ @PANi. This modification improves the overall electronic conductivity of the MnCo₂ O₄ @PANi-rGO because of the dual conductive functions of rGO and PANi; it also provides a buffer for the changes in electrode volume during cycling, thus improving the lithium-storage performance of MnCo₂ O₄ @PANi-rGO. The electrochemical performance of the samples was evaluated by charge/discharge cycling testing, cyclic voltammetry, and electrochemical impedance spectroscopy. MnCo₂ O₄ @PANi-rGO delivers a discharge capacity of 745 mAh g^-1 and a Coulombic efficiency of 100 % after 1050 cycles at a current density of 500 mA g^-1 , and is a promising anode material for lithium-ion batteries.

Conversion-type Anode Materials for Alkali-Ion Batteries: State of the Art and Possible Research Directions

In this study, the potential of conversion-type anode materials for alkali-ion batteries has been examined and analyzed in terms of the parameters of prime importance for practical alkali-ion systems. Issues like voltage hysteresis, discharge profile, rate stabilities, cyclic stabilities, irreversible capacity loss, and Columbic efficiencies have been specifically addressed and analyzed as the key subjects. Relevant studies on achieving a better performance by addressing one or more of the issues have been carefully selected and outlook has been presented on the basis of this literature. Mechanistic insights into the subject of conversion reactions are discussed in light of the use of recent and advanced techniques like in situ transmission electron microscopy, in operando X-ray diffraction, and X-ray absorption spectroscopy. Three-dimensional plots depicting the performance of different materials, morphologies, and compositions with respect to these parameters are also presented to highlight the systematic of multiparameter dependencies. Inferences are drawn from these plots in the form of a short section at the end, which should be helpful to the readers, especially young researchers. We believe that this study differs from others on the subject in being focused toward addressing the practical limitations and providing possible research directions to achieve the best possible results from conversion-type anode materials.