No abstract

Despite the design of nano-structured SnO 2 anodes has attracted much attention because of its high theoretical capacity, good electron mobility, and low potential of lithium-ion intercalation, challenges remain due to their weak mechanical stability, complex processing and rapid capacity decay. The one-dimensional binder-free porous CC/SnO 2 nanotube arrays are synthesized with a well-suited core etching method to meet the needs of steady operation of flexible devices under mechanical deformation. This porous, binder-free nanostructure has large contact area with the electrolyte and excellent electron transport performance. The electrochemical measurements demonstrate that these nanotube arrays have high energy density and high-rate capability. After 500 cycles at a current density of 200 mA g −1 , their stable capacity remains at 595.7 mA h g −1 .

Graphene-based MoS 2 nanocomposites are expected to be promising anode materials for lithium ion batteries because of their large specific capacity and high conductivity. However, the aggregation of graphene and the weak interaction between the two components hinder their practical application. Inspired by the sandwich structure, novel three-dimensional flower-like MoS 2-PrGO sandwich composites were proposed as an advanced anode material for lithium-ion batteries. The separated 2D ultrathin rGO nano-sheets were connected by PEO chains and assembled into a well-organized 3D layered spatial structure, which not only avoids the aggregation of graphene but also accommodates a high mass loading of the micro-scale MoS 2 nano-flowers. MoS 2 nano-flowers with open architecture deliver large specific area. The rGO interlayers act as a conductive framework, making all flower-like MoS 2 nano-stuffing electrochemically active. The ultra-thin 2D nano-sheets provide excellent cycle stability due to their neglectable volume changes during cycling. The 3D flower-like MoS 2-PrGO sandwich composites deliver high energy density, excellent conductivity and stable cyclic performance during charge-discharge process. With a nearly 100% coulombic efficiency, their reversible capacity is retained at 1,036 mA h g −1 even after 500 cycles at current densities of 100 mA g −1. This novel design strategy provides a broad prospect for the development of advanced anode materials for superior lithium storage.

SnO2 is a promising anode material for lithium-ion batteries due to its high theoretical specific capacity and low operation voltage. However, its poor cycling performance hinders its commercial application. In order to improve the cycling stability of SnO2 electrodes, novel flower-like SnO2/TiO2 hollow spheres were prepared by facile hydrothermal method using carbon spheres as templates. Their flower-like shell and mesoporous structure highlighted a large specific surface area and excellent ion migration performance. Their TiO2 hollow sphere matrix and 2D SnO2 nano-flakes ensured good cycle stability. The electrochemical measurements indicated that novel flower-like SnO2/TiO2 hollow spheres delivered a high specific capacity, low irreversible capacity loss and superior rate performance. After 1,000 cycles at current densities of 200 mA g−1, the capacity of the flower-like SnO2/TiO2 hollow spheres was still maintained at 720 mAh g−1. Their rate capacity reached 486 mAh g−1 when the current densities gradually increase to 2,000 mA g−1.

The performance of anodes of lithium-ion batteries relies largely on the architecture and composition of the hybrid active materials. We present a two-step, seed-free, solution-based method for the direct growth of hierarchical charantia-like TiO 2 /Fe 2 O 3 core/shell nanotube arrays on carbon cloth substrates. An ultrahigh loading of the nanomaterial on carbon fibers was achieved with this method without the use of a binder. This three-dimensional porous hollow architecture and its direct contact with the CC current collector ensure an efficient electronic pathway. The hollow TiO 2 framework effectively protects the hierarchical charantia-like TiO 2 /Fe 2 O 3 hollow core/shell arrays from collapsing because of its negligible volume change during cycling. Meanwhile, the self-assembled α-Fe 2 O 3 hollow nanospheres guarantee a large capacity and contact area with the electrolyte. This flexible anode with a 3D porous charantia-like hollow architecture exhibits high cycle performance, reversible capacity, and rate capability. These nanotube arrays maintain a high reversible capacity of 875 mAh g −1 after 200 cycles at a current density of 200 mA g −1. This simple, cost-effective, and scalable electrode fabrication strategy can be implemented in the fabrication of high-performance wearable energy storage devices.