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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]

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]

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]