One-pot synthesis of manganese oxide-carbon composite microspheres with three dimensional channels for Li-ion batteries

The fabrication of manganese oxide-carbon composite microspheres with open nanochannels and their electrochemical performance as anode materials for lithium ion batteries are investigated. Amorphous-like Mn₃O₄ nanoparticles embedded in a carbon matrix with three-dimensional channels are fabricated by one-pot spray pyrolysis. The electrochemical properties of the Mn₃O₄ nanopowders are also compared with those of the Mn₃O₄-C composite microspheres possessing macropores resembling ant-cave networks. The discharge capacity of the Mn₃O₄-C composite microspheres at a current density of 500 mA g⁻¹ is 622 mA h g⁻¹ after 700 cycles. However, the discharge capacity of the Mn₃O₄ nanopowders is as low as 219 mA h g⁻¹ after 100 cycles. The Mn₃O₄-C composite microspheres with structural advantages and high electrical conductivity have higher initial discharge and charge capacities and better cycling and rate performances compared to those of the Mn₃O₄ nanopowders.

Direct large-scale synthesis of 3D hierarchical mesoporous NiO microspheres as high-performance anode materials for lithium ion batteries

Hierarchically porous materials are an ideal material platform for constructing high performance Li-ion batteries (LIBs), offering great advantages such as large contact area between the electrode and the electrolyte, fast and flexible transport pathways for the electrolyte ions and the space for buffering the strain caused by repeated Li insertion/extraction. In this work, NiO microspheres with hierarchically porous structures have been synthesized via a facile thermal decomposition method by only using a simple precursor. The superstructures are composed of nanocrystals with high specific surface area, large pore volume, and broad pore size distribution. The electrochemical properties of 3D hierarchical mesoporous NiO microspheres were examined by cyclic voltammetry and galvanostatic charge-discharge studies. The results demonstrate that the as-prepared NiO nanospheres are excellent electrode materials in LIBs with high specific capacity, good retention and rate performance. The 3D hierarchical mesoporous NiO microspheres can retain a reversible capacity of 800.2 mA h g(-1) after 100 cycles at a high current density of 500 mA g(-1).

Encapsulation of MnO nanocrystals in electrospun carbon nanofibers as high-performance anode materials for lithium-ion batteries

A novel and controllable approach is developed for the synthesis of MnO nanocrystals embedded in carbon nanofibers (MnO/CNFs) through an electrospinning process. The as-formed MnO/CNFs have a porous structure with diameters of 100-200 nm and lengths up to several millimeters. When used as an anode material for lithium-ion batteries, the resulting MnO/CNFs exhibit superior electrochemical performances with high specific capacity, good cyclability, and excellent rate capability. The unique porous carbon nanofibers (PCNFs) can not only improve the contact area between the electrode and the electrolyte, but also alleviate the impact of the large volume effect of MnO during the electrochemical cycling. It is expected that the present synthetic strategy can be extended to synthesize other nanostructured oxides encapsulated in carbon nanofibers for extensive energy transfer and storage applications.

All-nanowire based Li-ion full cells using homologous Mn2O3 and LiMn2O4

We report an all-nanowire based flexible Li-ion battery full cell, using homologous Mn2O3 and LiMn2O4 nanowires for anodes and cathodes, respectively. The same precursors, MnOOH nanowires, are transformed from hydrothermally grown MnO2 nanoflakes and directly attached on Ti foils via reaction with poly(vinyl pyrrolidone). The Mn2O3 anode and LiMn2O4 cathode are subsequently formed by thermal annealing and reaction with lithium salt, respectively. The one-dimensional nanowire structures provide short lithium-ion diffusion path, good charge transport, and volume flexibility for Li(+) intercalation/deintercalation, thus leading to good rate capability and cycling performance. As proof-of-concept, the Mn2O3 nanowire anode delivers an initial discharge capacity of 815.9 mA h g(-1) at 100 mA g(-1) and maintains a capacity of 502.3 mA h g(-1) after 100 cycles. The LiMn2O4 nanowire cathodes show a reversible capacity of 94.7 mA h g(-1) at 100 mA g(-1) and high capacity retention of ∼ 96% after 100 cycles. Furthermore, a flexible Mn2O3//LiMn2O4 lithium ion full cell is fabricated, with an output voltage of >3 V, low thickness of 0.3 mm, high flexibility, and a specific capacity of 99 mA h g(-1) based on the total weight of the cathode material. It also exhibits good cycling stability with a capacity of ∼ 80 mA h g(-1) after 40 charge/discharge cycles.

Synthesis of Mn₂O₃ nanomaterials with controllable porosity and thickness for enhanced lithium-ion batteries performance

Mn₂O₃ has been demonstrated to be a promising electrode material for lithium-ion batteries. Thus, the fabrication of Mn₂O₃ nanomaterials with high specific capacity and cycling stability is greatly desired. Here we report a simple but effective method to synthesis Mn₂O₃ nanomaterials from a Mn(OH)₂ precursor, which was prepared from manganese acetate in ethylene glycol and water at 180 °C for 12 h. The morphology and sheet thickness of Mn(OH)₂ precursor could be tuned by controlling the ethylene glycol/H₂O volume ratio, resulting in a further tunable morphology and sheet thickness of the porous Mn₂O₃ nanomaterials. In the electrochemical tests the prepared Mn₂O₃ nanomaterials, with the porous architecture and thin thickness exhibited a high and stable reversible capacity, indicating that both small thickness and porous sheets structure are crucial for improving the electrochemical performance of Mn₂O₃ in terms of specific capacity and stability.

Morphology-mediated tailoring of the performance of porous nanostructured Mn2O3 as an anode material

The experiments determined the effects of different morphologies of synthesized porous Mn₂O₃ on its performance as an anode material in Li-ion batteries.

Fabrication and formation mechanism of Mn2O3 hollow nanofibers by single-spinneret electrospinning

Well-defined Mn₂O₃ hollow nanofibers with a smooth wall were successfully fabricated by the single-spinneret electrospinning method. The possible formation mechanism was introduced based on temperature-dependent experiments.

Recent advances in Mn-based oxides as anode materials for lithium ion batteries

The Mn-based oxides including MnO, Mn₃O₄, Mn₂O₃, MnO₂, CoMn₂O₄, ZnMn₂O₄and their carbonaceous composite/oxide supports with different morphologies and compositions as anode materials are reviewed.

High performance pure sulfur honeycomb-like architectures synthesized by a cooperative self-assembly strategy for lithium–sulfur batteries

Honeycomb-like pure sulfur architectures were synthesized by a cooperative self-assembly strategy for improving electrochemical performance of Li–S batteries.

Green and facile fabrication of hollow porous MnO/C microspheres from microalgaes for lithium-ion batteries

Hollow porous micro/nanostructures with high surface area and shell permeability have attracted tremendous attention. Particularly, the synthesis and structural tailoring of diverse hollow porous materials is regarded as a crucial step toward the realization of high-performance electrode materials, which has several advantages including a large contact area with electrolyte, a superior structural stability, and a short transport path for Li(+) ions. Meanwhile, owing to the inexpensive, abundant, environmentally benign, and renewable biological resources provided by nature, great efforts have been devoted to understand and practice the biotemplating technology, which has been considered as an effective strategy to achieve morphology-controllable materials with structural specialty, complexity, and related unique properties. Herein, we are inspired by the natural microalgae with its special features (easy availability, biological activity, and carbon sources) to develop a green and facile biotemplating method to fabricate monodisperse MnO/C microspheres for lithium-ion batteries. Due to the unique hollow porous structure in which MnO nanoparticles were tightly embedded into a porous carbon matrix and form a penetrative shell, MnO/C microspheres exhibited high reversible specific capacity of 700 mAh g(-1) at 0.1 A g(-1), excellent cycling stability with 94% capacity retention, and enhanced rate performance of 230 mAh g(-1) at 3 A g(-1). This green, sustainable, and economical strategy will extend the scope of biotemplating synthesis for exploring other functional materials in various structure-dependent applications such as catalysis, gas sensing, and energy storage.

CoMn(2)O(4) spinel hierarchical microspheres assembled with porous nanosheets as stable anodes for lithium-ion batteries

Herein, we report the feasibility to enhance the capacity and stability of CoMn₂O₄ anode materials by fabricating hierarchical mesoporous structure. The open space between neighboring nanosheets allows for easy diffusion of the electrolyte. The hierarchical microspheres assembled with nanosheets can ensure that every nanosheet participates in the electrochemical reaction, because every nanosheet is contacted with the electrolyte solution. The hierarchical structure and well interconnected pores on the surface of nanosheets will enhance the CoMn₂O₄/electrolyte contact area, shorten the Li⁺ ion diffusion length in the nanosheets, and accommodate the strain induced by the volume change during the electrochemical reaction. The last, hierarchical architecture with spherical morphology possesses relatively low surface energy, which results in less extent of self-aggregation during charge/discharge process. As a result, CoMn₂O₄ hierarchical microspheres can achieve a good cycle ability and high rate capability.