Thin and lightweight flexible lithium-ion batteries (LIBs) with high volumetric capacities are crucial for the development of flexible electronic devices. In the present work, we reported a paper-like ultrathin and flexible Si/carbon nanotube (CNT) composite anode for LIBs, which was realized by conformal electrodeposition of a thin layer of silicon on CNTs at ambient temperature. This method was quite simple and easy to scale up with low cost as compared to other deposition techniques, such as sputtering or CVD. The flexible Si/CNT composite exhibited high volumetric capacities in terms of the total volume of active material and current collector, surpassing the most previously reported Si-based flexible electrodes at various rates. In addition, the poor initial coulombic efficiency of the Si/CNT composites can be effectively improved by prelithiation treatment and a commercial red LED can be easily lighted by a full pouch cell using a Si/CNT composite as a flexible anode under flat or bent states. Therefore, the ultrathin and flexible Si/CNT composite is highly attractive as an anode material for flexible LIBs.

Although the electrochemical properties of porous LiMn 2 O 4 microspheres are usually improved compared to those of irregular LiMn 2 O 4 particles, the effects of the different synthesis conditions on the preparation of the porous LiMn 2 O 4 microspheres are rarely discussed in detail. In the present work, porous LiMn 2 O 4 microspheres were successfully synthesized by using molten LiOH and porous Mn 2 O 3 spheres as a template. Multiple factors were considered in the preparation process, including reagent concentration, pH, adding mode, heating time, etc. The morphology of the MnCO 3 template was crucial for the preparation of porous LiMn 2 O 4 microspheres and it was mainly affected by the concentration of reactants and the pH value of the solution during the precipitation process. During the lithiation of Mn 2 O 3 microspheres, the heating temperature and the ratio between Mn 2 O 3 and lithium salt were the most significant variables in terms of control over the morphology and purity of the LiMn 2 O 4 microspheres. Furthermore, we demonstrated that the porous LiMn 2 O 4 microspheres presented better rate capability and cyclability compared to commercial LiMn 2 O 4 powder as cathode materials for lithium-ion batteries (LIBs). This study not only highlights the shape-controllable synthesis of LiMn 2 O 4 microspheres as promising cathode materials, but also provides some useful guidance for the synthesis of porous LiMn 2 O 4 microspheres and other LIB' electrode materials.

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