Multilayered Si/RGO anode nanostructures, featuring alternating Si nanoparticle (NP) and RGO layers, good mechanical stability, and high electrical conductivity, allow Si NPs to easily expand between RGO layers, thereby leading to high reversible capacity up to 2300 mAh g(-1) at 0.05 C (120 mA g(-1) ) and 87% capacity retention (up to 630 mAh g(-1) ) at 10 C after 152 cycles.

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Lithium titanate (LTO), Li 4 Ti 5 O 12 is a promising material for energy storage due to its high-rate capabilities and safety. However, gas generation, which can be observed under high-temperature operation, present a challenge to the large-scale application of lithium ion batteries made from LTO anodes. Here we analyzed sources of gas generation in an LTO system through isotopic tagging of primary suspected sources of H 2 . Specifically, we added small amounts of heavy water (D 2 O) to the electrolyte, D 2 O to the LTO electrode, or deuterated dimethyl carbonate (DMC) to the electrolyte. Upon cycling, the isotopic tagging method enables the separation of deuterated from non-deuterated gas products using combined gas chromatography and mass spectroscopy (GC/MS) analysis. The results demonstrate that cell performance and generation of H 2 are both strongly related to moisture content within the cells. Cells with deuterated DMC in the electrolyte show negligible breakdown as determined by the lack of H-D/D 2 gas production when compared to samples that contain D 2 O added into the electrode or electrolyte. These results indicate that the primary source of gas generation in LTO-based cells is residual moisture in the electrodes and electrolyte, reinforcing the importance of low-moisture processing conditions for LTO-based lithium ion batteries. The rechargeable lithium ion battery is one of the most important energy storage technologies today as the power source in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs) and full electric vehicles (EVs) as well as for large-scale storage of renewable energy.1 Current lithium ion batteries typically utilize a graphite anode because of the low potential vs Li, good cycle life and good rate capability. However, safety is a major issue that hinders the wide scale usage of lithium ion batteries in automobiles. At elevated temperatures using graphite anodes, for example, the solid electrolyte interphase (SEI) between the non-aqueous electrolyte and the graphite surface becomes less stable and may even decompose at temperatures as low as 60• C. 2,3 Lithium ion batteries containing lithium titanate (LTO) anodes, Li 4 Ti 5 O 12 , are promising energy storage systems for their higher rate capabilities, safety, and long cycle-life, owing to their zero volumetric growth during lithiation 4,5 and higher anode voltage compared to graphite. Gas generation is a common phenomenon leading to the degradation of battery performance in Li-ion batteries. In LTO specifically, the gas generation and associated swelling, which are accelerated under high-temperature operation, present a challenge to the widespread application of lithium ion batteries made from LTO anodes. 6,7 Much research has focused on gas evolution in LTO anode based cells. It is well known that much of the gas generation can be attributed to chemical decomposition and redox decomposition of the electrolyte solvents on the anode or cathode. A well-defined mechanism for gas generation from LTO based cell...

Silicon, an anode material with the highest capacity for lithium-ion batteries, needs to improve its cyclic performance prior to practical applications. Here, we report on a novel design of Si/metal composite anode in which Si nanoparticles are welded onto surfaces of metal particles by forming intermetallic interphases through a rapid heat treatment. Unlike pure Si materials that gradually lose electrical contact with conductors and binders upon repeated charging and discharging cycles, Si in the new Si/metal composite can maintain the electrical contact with the current collector through the intermetallic interphases, which are inactive and do not lose physical contact with the conductors and binders, resulting in significantly improved cyclic performance. Within 100 cycles, only 23.8% of the capacity of the pure Si anode is left while our Si/Ni anode obtained at 900 °C maintains 73.7% of its capacity. Therefore, the concept of employing intermetallic interphases between Si nanoparticles and metal particles provides a new avenue to improve the cyclic performance of Si-based anodes.

Tin is a promising anode candidate for nextgeneration lithium-ion batteries with a high energy density, but suffers from the huge volume change (ca. 260 %) upon lithiation. To address this issue, here we report a new hierarchical tin/carbon composite in which some of the nanosized Sn particles are anchored on the tips of carbon nanotubes (CNTs) that are rooted on the exterior surfaces of micro-sized hollow carbon cubes while other Sn nanoparticles are encapsulated in hollow carbon cubes. Such a hierarchical structure possesses a robust framework with rich voids, which allows Sn to alleviate its mechanical strain without forming cracks and pulverization upon lithiation/de-lithiation. As a result, the Sn/C composite exhibits an excellent cyclic performance, namely, retaining a capacity of 537 mAh g À1 for around 1000 cycles without obvious decay at a high current density of 3000 mA g À1 .Existing commercial graphite anodes are capable of delivering a capacity of approximately 330 mAh g À1 , thereby approaching its theoretical capacity (372 mAh g À1 ). New anodes are required to meet the demands of next-generation lithium-ion batteries (LIBs) for high energy and power densities and a long cycle life. Sn, despite its high costs, is of significant interest and has been investigated extensively because of its high capacity (993.4 mAh g À1 ; from Sn to Li 4.4 Sn), abundance, and environmentally-friendliness; however, a huge volume change of the Sn anode (ca. 260 %) upon lithiation leads to very poor cyclic performance, inhibiting its practical applications.To address this issue, besides employing Sn-based nanocrystals [1,2] and thin films, [3][4][5] forming SnM (M = Co, [6] Cu, [7]