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Fe2O3 with high theoretical capacity (1007 mA h g−1) and low cost is a potential anode material for lithium‐ion batteries (LIBs), but its practical application is restricted by its low electrical conductivity and large volume changes during lithiation/delithiation. To solve these problems, Fe2O3@Ti3C2Tx composites were synthesized by a mussel‐like modification method, which relies on the self‐polymerization of dopamine under mild conditions. During polymerization, the electronegative group (−OH) on dopamine can easily coordinate with Fe3+ ions as well as form hydrogen bonds with the −OH terminal group on the surface of Ti3C2Tx, which induces a uniform distribution of Fe2O3 on the Ti3C2Tx surface and mitigates self‐accumulation of MXene nanosheets. In addition, the polydopamine‐derived carbon layer protects Ti3C2Tx from oxidation during the hydrothermal process, which can further improve the electrical conductivity of the composites and buffer the volume expansion and particle agglomeration of Fe2O3. As a result, Fe2O3@Ti3C2Tx anodes exhibit ~100 % capacity retention with almost no capacity loss at 0.5 A g−1 after 250 cycles, and a stable capacity of 430 mA h g−1 at 2 A g−1 after 500 cycles. The unique structural design of this work provides new ideas for the development of MXene‐based composites in energy storage applications. [ABSTRACT FROM AUTHOR]

In this work, we successfully designed and synthesized Ge nanoparticles encapsulated in a carbon matrix and supported by three-dimensional interconnected porous N-doped carbon foam (3D Ge/C-NCF) nanoarchitecture. When applied as an anode material for lithium ion batteries, the obtained composite electrode exhibits high capacity of 878.1 mAh g −1 at a current density of 0.5 A g −1 after 150 cycles. Additionally, it also achieves excellent rate capability and cycling stability. The significant improved electrochemical performance of Ge/C-NCF can be attributed to the synergetic effects of the carbon matrix and the N-doped carbon framework: including a highly conductive carbon network and a structure with large porous for mitigates volume changes of Ge nanoparticles. This study of the composite electrode may provide an interesting method to creating efficient and practical electrodes for those that suffer from huge volume expansion for energy storage applications. [ABSTRACT FROM AUTHOR]

Polythiophene-coated porous silicon core-shell nanospheres (Si@PTh) composite are synthesized by a simple chemical oxidative polymerization approach. The polythiophene acts as a flexible layer to hold silicon grains when they are repeatedly alloying/dealloying with lithium during the discharge/charge process. The long lifespan and high-current-density rate ­capability (at a current of 8 A g−1) of the Si@PTh composite are vastly improved compared with as-prepared Si spheres. Typically, these Si@PTh composite electrodes achieve a reversible capacity of 1130.5 mA h g−1 at 1 A g−1 current density after 500 cycles, and can even possess a discharge capacity up to 451.8 mA h g−1 at 8 A g−1. The improved electrochemical performance can be ascribed to the synergy effects of the flexible PTh coating and the distinctive core-shell nanospheres with porous structure, which can largely alleviate the volume expansion of the Si during alloying with lithium. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) titanium dioxide@germanium (TiO2@Ge) core-shell nanorod arrays on carbon textiles are fabricated by a facile two-step method and further investigated as flexible electrode for Li-ion batteries (LIBs). The synthesis of TiO2@Ge composite involves the hydrothermal growth of TiO2 nanorod arrays on carbon textiles and a subsequent coat with a thin layer of germanium with radio frequency (RF) magnetron sputtering. The TiO2 nanorod arrays can effectively not only increase the unit mass loading as a role of skeleton but also remarkably enhance the electrical conductivity via control the lithiation/delithiation voltage in the range of 0.01-1.0 V, where TiO2 can be in situ lithiated to LixTiO2 after the first discharge cycle. Moreover, each TiO2@Ge nanorod has enough space to accommodate the large volume expansion of Ge during charge and discharge cycles. Benefiting from unique electrode architectures, this additive free, self-supported electrode exhibits the high reversible capacity, outstanding rate capability, and the extremely long cycling stability even at a high rate (700.3 mAh g−1 is still retained at 5 A g−1 after 600 cycles). [ABSTRACT FROM AUTHOR]

Here, germanium (Ge) nanofilm as the high-capacity electrode was deposited on the three-dimensional porous nickel foam substrate by radio frequency sputtering. Then, cyclized-polyacrylonitrile (PAN) was coated on the surface of Ge nanofilm to get the excellent rate capability and cycle stability owing to the poor cycle life of the as-prepared Ge nanofilm. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy were employed to analyze the microstructure and morphology of the Ge/cyclized-PAN electrodes. The Ge/cyclized-PAN manifests excellent electrochemical performance with high specific capacity and good cycling stability due to the unique structural features. At the charge-discharge rate of 0.1, 0.2, 0.5, 1, 2, and 5 C over a voltage window of 0.01-1.0 V, the discharge capacities of the composite are 731, 722, 701, 676, 621, and 566 mAh g, respectively. The specific capacity retention is up to 98 % with less capacity fading after 100 cycles at 1 C. [ABSTRACT FROM AUTHOR]

Lithium‐ion batteries (LIBs) with outstanding energy and power density have been extensively investigated in recent years, rendering them the most suitable energy storage technology for application in emerging markets such as electric vehicles and stationary storage. More recently, sodium, one of the most abundant elements on earth, exhibiting similar physicochemical properties as lithium, has been gaining increasing attention for the development of sodium‐ion batteries (SIBs) in order to address the concern about Li availability and cost—especially with regard to stationary applications for which size and volume of the battery are of less importance. Compared with traditional intercalation reactions, conversion reaction‐based transition metal oxides (TMOs) are prospective anode materials for rechargeable batteries thanks to their low cost and high gravimetric specific capacities. In this review, the recent progress and remaining challenges of conversion reactions for LIBs and SIBs are discussed, covering an overview about the different synthesis methods, morphological characteristics, as well as their electrochemical performance. Potential future research directions and a perspective toward the practical application of TMOs for electrochemical energy storage are also provided. [ABSTRACT FROM AUTHOR]

Although silicon is considered as one of the most promising anode materials in next‐generation lithium‐ion batteries, large volumetric expansion during cycling hampers its practical application. The fabrication of silicon/carbon composites is an effective way to improve electrical conductivity and inhibit electroactive material delaminating from the current collector. Herein, a graphitic carbon‐coated porous silicon nanospheres (p‐SiNSs@C) composite is prepared through a chemical vapor deposition (CVD) technique by using the magnesiothermic reduction by‐product MgO as a template and catalyst. With the template of in situ generation of MgO, the p‐SiNSs@C material is obtained in a very short time. Due to the graphitic carbon shell and porous structure inside the silicon nanospheres, the obtained p‐SiNSs@C, with 8 min carbon growing time (p‐SiNSs@C‐2), deliver a high initial reversible capacity of 2220 mAh g−1 at 0.1 A g−1 and respectable rate capability. Furthermore, the p‐SiNSs@C‐2//LiCoO2 Li‐ion full cell displays a high energy density of ≈409 Wh kg−1 and good cycling performance. The high performance of the p‐SiNSs@C‐2 composite can be attributed to the synergistic effect of nanoscale‐sized Si, porous structure, and stable carbon shell. [ABSTRACT FROM AUTHOR]

A highly graphitized carbon on a silicon monoxide (SiO) surface coating at low temperature, based on polymer precursor π–π stacking, was developed. A novel conductive and electrochemically stable carbon coating was rationally designed to modify the SiO anode materials by controlling the sintering of a conductive polymer, a pyrene-based homopolymer poly (1-pyrenemethyl methacrylate; PPy), which achieved high graphitization of the carbon layers at a low temperature and avoided silicon carbide formation and possible SiO material transformation. When evaluated as the anode of a lithium-ion battery (LIB), the carbon-coated SiO composite delivered a high discharge capacity of 2058.6 mAh/g at 0.05 C of the first formation cycle with an initial Coulombic efficiency (ICE) of 62.2%. After 50 cycles at 0.1 C, this electrode capacity was 1090.2 mAh/g (~82% capacity retention, relative to the capacity of the second cycle at 0.1 °C rate), and a specific capacity of 514.7 mAh/g was attained at 0.3 C after 500 cycles. Furthermore, the coin-type full cell composed of the carbon coated SiO composite anode and the Li[Ni0.5Co0.2Mn0.3O2] cathode attained excellent cycling performance. The results show the potential applications for using a π–π stacking polymer precursor to generate a highly graphitize coating for next-generation high-energy-density LIBs. [ABSTRACT FROM AUTHOR]