the LIBs. Considerable improvements in the design and optimization of anode composition and structure are still required.This note reports our design and implementation of a SnS 2based nanocomposite anode for the NIBs. SnS 2 has a CdI 2 -type of layered structure (a = 0.3648 nm, c = 0.5899 nm, space group P3m1) consisting of a layer of tin atoms sandwiched between two layers of hexagonally close packed sulfur atoms. This layered structure with a large interlayer spacing (c = 0.5899 nm) should easy the insertion and extraction of guest species and adapt more easily to the volume changes in the host during cycling. This has been confi rmed by the performance of SnS 2 as a reversible lithium storage host in several studies. [ 17 ] The electrochemical properties of layered sulfi des (SnS 2 , MoS 2 , WS 2 ) were further improved by integration with graphene. The structural compatibility between the two layered compounds and the good electronic properties of graphene led to very stable composites (i.e. long cycle-life) with high reversible capacity and good rate performance in LIB applications. [ 18 ] The SnS 2 layer structure should also be viable for reversible Na + storage since, in comparison with tin and other tin-based materials, it has the largest buffer for the volume changes in Na-Sn reactions. The LIB developmental efforts also suggest layer-structured SnS 2reduced graphene oxide (SnS 2 -RGO) nanocomposites as an improved version of the SnS 2 anode.The design of the SnS 2 -RGO hybrid structure for reversible storage of Na + was based on the following materials principles: 1) a large interlayer spacing in the SnS 2 structure benefi ting Na + intercalation and diffusion, and more buffering space for benefi cial adjustment the volume changes in the host during cycling; 2) fast collection and conduction of electrons through a highly conductive RGO network; and 3) inhibition of Sn (Na x Sn) aggregation during cycling by RGO after material hybridization. The experimental results validated the expectations: the SnS 2 -RGO anode delivered a high charge (desodiation) specifi c capacity of 630 mAh g −1 at 0.2 A g −1 , and more impressively, 544 mAh g −1 after a ten-fold increase in current density to 2 A g −1 . The electrode was also very stable to cycling; providing a nearly unvarying capacity of 500 mAh g −1 at 1 A g −1 even after 400 charge-discharge cycles.The SnS 2 -RGO nanocomposite was produced by a facile hydrothermal route from a mixture of tin (IV) chloride, thioacetamide (TAA) and graphene oxide (GO) (details in the Experimental Section). In the comparison of the X-ray diffraction (XRD) patterns of the SnS 2 -RGO composite, SnS 2 and GO in Figure 1 a, GO only displayed a single diffraction peak at 10.9° from the (002) planes. [ 19 ] The powder XRD patterns of SnS 2 and The idea of sodium-ion batteries (NIBs) as a substitute of lithium-ion batteries (LIBs) for grid-scale energy storage was initially driven by cost considerations. [ 1 ] Research in the last several years has shown that NIBs are not necessar...

Easy to hollow: A hollow porous Si nanocomposite with Ag nanoparticles (NPs) is prepared (see scheme; PS=polystyrene, HP=hollow porous). The free volume in the HPSi structure effectively cushioned the volume change in Li–Si alloying and de‐alloying reactions, giving an impressive performance as a high‐capacity anode for lithium‐ion batteries.

No abstract

Graphene-encapsulated ordered aggregates of Fe(3)O(4) nanoparticles with nearly spherical geometry and hollow interior were synthesized by a simple self-assembly process. The open interior structure adapts well to the volume change in repetitive Li(+) insertion and extraction reactions; and the encapsulating graphene connects the Fe(3)O(4) nanoparticles electrically. The structure and morphology of the graphene-Fe(3)O(4) composite were confirmed by X-ray diffraction, scanning electron microscopy, and high-resolution transmission microscopy. The electrochemical performance of the composite for reversible Li(+) storage was evaluated by cyclic voltammetry and constant current charging and discharging. The results showed a high and nearly unvarying specific capacity for 50 cycles. Furthermore, even after 90 cycles of charge and discharge at different current densities, about 92% of the initial capacity at 100 mA g(-1) was still recoverable, indicating excellent cycle stability. The graphene-Fe(3)O(4) composite is therefore a capable Li(+) host with high capacity that can be cycled at high rates with good cycle life. The unique combination of graphene encapsulation and a hollow porous structure definitely contributed to this versatile electrochemical performance.

Two-dimensional nanosheets can leverage on their open architecture to support facile insertion and removal of Li(+) as lithium-ion battery electrode materials. In this study, two two-dimensional nanosheets with complementary functions, namely nitrogen-doped graphene and few-layer WS2, were integrated via a facile surfactant-assisted synthesis under hydrothermal conditions. The layer structure and morphology of the composites were confirmed by X-ray diffraction, scanning electron microscopy and high-resolution transmission microscopy. The effects of surfactant amount on the WS2 layer number were investigated and the performance of the layered composites as high energy density lithium-ion battery anodes was evaluated. The composite formed with a surfactant : tungsten precursor ratio of 1 : 1 delivered the best cyclability (average of only 0.08% capacity fade per cycle for 100 cycles) and good rate performance (80% capacity retention with a 50-fold increase in current density from 100 mA g(-1) to 5000 mA g(-1)), and may find uses in power-oriented applications.