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Owing to their multiple redox couples, titanium–niobium-based oxides are still considered promising candidates for use as anodes for safe, rechargeable lithium ion batteries with high energy and power densities. Titanium–niobium-based oxide electrodes have, however, exhibited relatively poor cycling performance as a result of pulverization. In this study, we report on a simple two-step solid-state reaction route for producing hybrid composites of Ti 2 Nb 10 O 29 (TNO) anchored on reduced graphene oxide (RGO), and the electrochemical performance of the resulting TNO/RGO composites. Solid-state reactions enable both the formation of TNO and the uniform distribution of RGO in the TNO/RGO composites. The TNO/RGO composites exhibited discharge and charge capacities of 261 and 256 mAh g −1 , respectively, with much better cycling performance (182 mAh g −1 after the 50th cycles) and rate capability (165 mAh g −1 at a current density of 500 mA g −1 ) compared to the pure TNO. [ABSTRACT FROM AUTHOR]

Small amount of reduce graphene oxide (rGO) nanosheets modified Li 4 Ti 5 O 12 nanoparticles composite has been synthesized by a facile and environmental in-situ hydrothermal reaction with subsequent annealing. The small amount of rGO (only 1.2 wt. %) greatly improves the whole morphology and electrochemical performance of composite. The nanoparticles uniformly grow on the rGO nanosheets effective suppressing the agglomeration and enhancing the specific surface area. Meanwhile, the special discharge capacity is 187 mAh g −1 at 1 C and the high rates discharge capacity is 128 mAh g −1 at 80 C (discharge-charge time only 33s). In particular, the cells remain in good work condition after 2000 cycles at 80 C, which credibly evidence the excellent electrochemical performance as an anode for high-power LIBs. [ABSTRACT FROM AUTHOR]

Flower-like hydrogenated TiO 2 (B) nanostructures have been synthesized via a facile solvothermal approach combined with hydrogenation treatment. The obtained TiO 2 (B) nanostructures show uniform and hierarchical flower-like morphology with a diameter of 124 ± 5 nm, which are further constructed by primary nanosheets with a thickness of 10 ± 1.2 nm. The Ti 3+ species and/or oxygen vacancies are well introduced into the structures of TiO 2 (B) after hydrogen reduction, resulting in an enhancement in the electronic conductivity (up to 2.79 × 10 −3 S cm −1 ) and the modified surface electrochemical activity. When evaluated for lithium storage capacity, the hydrogenated TiO 2 (B) nanostructures exhibit enhanced electrochemical energy storage performances compared to the pristine TiO 2 (B) nanostructures, including high capacity (292.3 mA h g −1 at 0.5C), excellent rate capability (179.6 mA h g −1 at 10C), and good cyclic stability (98.4% capacity retention after 200 cycles at 10C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of oxygen vacancies and the unique flower-like morphologies. [ABSTRACT FROM AUTHOR]

Abstract: In this study, size effect of NiO particles has been studied as the anode material of lithium ion battery. It is found that NiO nanoparticles synthesized in confined space of ordered mesoporous silica behave anomalous high capacity and higher energy efficiency than sub-micro-sized NiO does. The higher energy efficiency is resulted from the reduction of the hysteresis loop between charge and discharge voltage plateaus, the main drawback of conversion reaction-based metal oxide anode materials. The interesting behavior is proposed to be the reversible formation/dissolution of solid electrolyte interphase (SEI) layers associated with 3-D porous, originally nanostructured NiO electrode that is able to remain stable during charge–discharge process. [Copyright &y& Elsevier]

Abstract: A new method for a facile synthesis of nano-silicon/carbon mesoporous composite is proposed. Silicon nanoparticles can be obtained through the magnesium silicide reduction of amorphous silica using high energy mechanical milling process. And mesoporous carbon matrix is fabricated via simple carbon coating method on Si nanoparticles followed by chemical etching of preexisting magnesium oxide nano-particles. This nano-silicon/carbon mesoporous composite electrode shows an excellent electrochemical performance as an anode for lithium ion batteries, achieving a reversible capacity of c.a. 1600 mAh g−1 over 50 cycles at a current of 1.0 A g−1 and superior rate capabilities with reversible capacity of about 1530 mAh g−1 at a discharge current density of 3 A g−1. [Copyright &y& Elsevier]

Abstract: The composite of manganese monoxide and multi-walled carbon nanotubes (MnO/MWNTs) is prepared hydrothermally by MWNTs and KMnO4 followed with a sintering process. After reducing KMnO4 as the reductant, the leftover MWNTs are found randomly distributed in the final MnO rods forming a conducting network. More importantly, they can buffer the volume change of MnO during lithium incorporation/extraction. As a result, the rate capability and cycling performance of MnO as an anode material for lithium ion batteries are significantly improved. The MnO/MWNTs composite shows a reversible capacity as high as 770.6 mA h g−1 and 455.3 mA h g−1 at the current density of 7.21 mA g−1 and 310.23 mA g−1 respectively between 0.01 and 3.5 V (vs. Li/Li+ hereafter). Furthermore, the capacity retention is over 92.4% after 200 cycles at 216.14 mA g−1 between 0.01 and 3.0 V. [Copyright &y& Elsevier]

Abstract: An efficient synthesis is used for the first time to prepare CuO/reduced graphene oxide nanocomposite anode materials for lithium ion batteries. Initially, copper oxide (CuO) nanoparticles are synthesized via a simple, facile and inexpensive microwave-assisted method within short reaction times (<20 min) and subsequent heat treatment at 500 °C for 5 h. The obtained pure CuO nanoparticles are mixed with 10 wt% of graphene nanosheets by the use of spex mill for 1 min. By short-time spex-milling, a unique CuO/reduced graphene oxide nanocomposite is obtained with a microstructure of multi-scale CuO nanoparticles homogeneously dispersed in a graphene matrix. The synthesized samples are characterized using X-ray diffraction and field-emission transmission electron microscopy studies. The spex-milled nanocomposite anode exhibits better electrochemical performance with higher reversible capacity and excellent cyclability in comparison with pure CuO nanoparticles. The initial discharge capacity of the pure CuO nanoparticles and their nanocomposite are 785.2 mAh g−1 and 1043.3 mAh g−1 with reversible capacity retention of 392.1 mAh g−1 and 516.4 mAh g−1 after 45 cycles respectively. The excellent electrochemical performance of CuO/reduced graphene oxide nanocomposite can be attributed to their unique structures, which intimately combine the conductive graphene nanosheets network with uniformly dispersed CuO nanoparticles. [Copyright &y& Elsevier]

Abstract: Li3V2(PO4)3/C cathode material is synthesized by a carbon-thermal reduction method using polyvinyl alcohol as carbon source at 700°C. The Li3V2(PO4)3/C electrode presents a high initial discharge capacity of 84.3, 111.1, 128.7, 129.2 and 132.1mAhg−1 at −20, 0, 25, 40 and 65°C between 3.0 and 4.3V, and 118.9, 132.1, 187.6, 180.3 and 172.2mAhg−1 between 3.0 and 4.8V at 0.1C, respectively. However, the electrode only delivers small discharge capacities at −20°C at 10C rate. The capacity fade at low temperatures is mainly attributed to the reduced ionic and electronic conductivity of the electrolyte, the increased impendence of solid electrolyte interface (SEI) and charge-transfer resistance on the electrolyte–electrode interfaces. At higher temperatures, the capacity increases with increasing temperature between 3.0 and 4.3V, but decreases between 3.0 and 4.8V. In the potential range of 3.0–4.8V, the larger crystal structural distortion and non-uniformity of SEI layer at high temperatures may be the main reasons for the capacity loss. [Copyright &y& Elsevier]

Abstract: The reduction mechanism of ethylene sulfite (ES) in propylene carbonate (PC) based electrolyte is investigated using density functional theory in gas phase. Based on the electron affinity energy and lowest unoccupied molecular orbital (LUMO) energy, it can be known that free ES is reduced most easily compared with ES-Li+ and ES-Li+-PC, generating SO2 and propanal. However, the binding energy of ES-Li+ and ES-Li+-PC is quite negative, indicating that both of them are more possible in electrolyte solution than the free ES. The reductive decomposition products of ES-Li+ and ES-Li+-PC are OSO2Li, OSO2Li-R and ethylene. OSO2Li and OSO2Li-R are the main compositions of the solid electrolyte interphase film on the anode of lithium ion battery, which inhibits the reductive decomposition of PC. These calculations provide a detailed explanation on the experimental phenomena. [Copyright &y& Elsevier]

Abstract: The geometric parameters of 1, 3-benzodioxol-2-one (BO) and propylene carbonate (PC) was optimized at the B3LYP/6-311++G (d, p) level of density functional theory (DFT) with the polarized continuum models (PCM). The obtained frontier molecular orbital energies and vertical electron affinities indicate that BO is reduced more easily than PC. The transition state (TS) of ring-opening reaction BO −1 →BO −1 was optimized and confirmed by vibrational frequency analysis and intrinsic reaction coordinate (IRC) method. The bond orders and atomic charge distribution of the stable points along the minimum energy path (MEP) were analyzed using the natural bond orbital (NBO) method at the B3LYP/6-311++G(d, p) level of DFT. With these calculated results, the reduction mechanism of BO for the formation of solid electrolyte interface (SEI) film on anode of lithium ion battery can be inferred as: BO+e→BO −1 →BO −1 →⋯→SEI Film. [Copyright &y& Elsevier]