In this work, we have fabricated a graphene-wrapped MnO/carbon nanofibers (MnO/CNFs@G) membrane by a facile electrospinning technique followed by an ambient pressure chemical vapor deposition (APCVD) process. The resultant MnO/CNFs@G membrane with uniform MnO particle distribution in porous carbon nanofibers and with a graphene layer covering not only facilitates the transport of both electrolyte ions and electrons to the MnO surface, but also relieves the pulverization that originated from the large volume change of MnO during the charge/discharge cycles. Interestingly, the free-standing and binder-free MnO/CNFs@G membranes can deliver a high reversible capacity of 946.5 mA h g−1 when the current density is switched back to 0.1 A g−1 after 110 cycles. Even at a high rate (10 A g−1), the electrode can still keep 426.7 mA h g−1 after 5000 cycles with coulombic efficiency of above 99%. This is the best specific capacity and longest cycling life reported for the MnO composite film anodes. We believe that the approach based on CNFs and CVD graphene as a structural support for the transition metal oxide can be potentially extended to improve the electrochemical performance of other electrode materials in lithium ion batteries.

•Densities, viscosities and speed of sound of binary systems are measured.•Excess molar volumes and viscosity deviations are calculated•The thermal expansion coefficients and isentropic bulk modulus are obtained.•This result will be helpful to understand molecular interactions and thermodynamic behaviorsIn this work, the experimental densities, viscosities, and speed of sound of binary mixtures of γ-butyrolactone (γ-GBL) + acetonitrile (ACN) and γ-GBL + dimethyl carbonate (DMC) have been measured at temperatures (293.15 to 333.15) K and γ-GBL + tetrahydrofuran (THF) at temperatures (293.15 to 323.15) K in the atmospheric pressure. Excess molar volumes (VE), viscosity deviations (Δη), thermal expansion coefficients (α), Bulk Modulus (βs), and the excess Gibbs energy (ΔGE*)ΔGE* were calculated. VE and Δη were fit with the Redlich–Kister equation and optimal fitting parameters are presented. It was found that values of VE and Δη are negative deviations from ideal behaviors for the three binary mixtures. With the concentration of γ-GBL decreasing, these excess properties for the these mixtures shows more negative deviations from ideal solutions, until a minimum values of VE are reached at mole fraction of γ-GBL around 0.5–0.6. Meantime, the negative deviation behaviors can be also observed when the temperature increases. This behavior can be explained by the strong interaction (dipole–dipole interaction and the dispersion force) between different molecules.

In this study, a series of LiFePO4/CNTs/C composite cathode materials for Li-ion batteries were synthesized by a simple homogeneous precipitation and subsequent annealing process. The investigation of the influence of CNTs on the structural and electrochemical characteristics of the LiFePO4/CNTs/C composites shows that the resulting composite materials exhibit smaller particle size, lower electron-transfer resistance, and faster lithium ion migration, which contribute to improve lithium ion transfer due to the incorporated CNTs. At 1C, the LiFePO4/CNTs/C composite delivers a stable specific capacity of ∼126 mA h g−1 after 500 cycles. At high rates (e.g. 10C), the CNT-incorporated composite is still able to deliver stable capacities of up to ∼119 mA h g−1, which is ∼42% greater than its pristine counterpart.

A series of La-doped Li3V2(PO4)3/C cathode materials for Li-ion batteries are synthesized by a sol–gel-assisted, low-temperature sintering process. La(NO3)3 acts not only as the La source, but also, together with the intermediate product LiNO3, promotes combustion, the ultrahigh exothermic energy that is advantageous for the nucleation process. The subsequent sintering process at 600 °C for 4 h is sufficient to produce highly crystalline La-doped Li3V2(PO4)3/C composites. The as-prepared cathode materials display smaller particle size, lower electron-transfer resistance and faster Li ion migration, which is ascribed to enhanced Li-ion transfer because of the La doping. The resulting Li3V1.96La0.04(PO4)3/C cathode has a stable specific capacity of 160 mA h g−1 at low charge–discharge rates over 100 cycles, and retained a stable capacity of up to 116 mA h g−1 at a rate of 5 C, which is 40% higher than the undoped pristine cathode.

We report a novel far-infrared (FIR) thermal reduction process to effectively reduce graphene oxide films for supercapacitor electrode applications. The binder-free graphene oxide films used in this study were produced by electro-spray deposition of a graphene oxide colloidal solution onto stainless steel current collectors. The reduction of graphene oxide was performed using a commercial FIR convection oven that is ubiquitous in homes for cooking and heating food. The reduction process incorporated a simple, one-step FIR irradiation carried out in ambient air. Further, the FIR irradiation process was completed in ∼3 min, wherein neither special atmosphere nor high temperature was employed, resulting in an economic, efficient and simplified processing technique. The as-produced FIR graphene electrode gave a specific capacitance of ∼320 F/g at a current density of ∼0.2 A/g with less than 94% loss in specific capacitance over 10,000 charge/discharge cycles. This is one of the best specific capacitances reported for all-carbon electrodes without any additives. Even at ultrafast charge/discharge rates (current densities as high as ∼100 A/g), the FIR graphene electrode still delivered specific capacitances in excess of 90 F/g. The measured energy and power densities of the FIR supercapacitors were found to be ∼3–6 times higher than commercial (activated carbon) supercapacitor devices. This excellent electrochemical performance of the FIR graphene coupled with its ease of production (in air at low temperatures) using a commercial home-use FIR convection oven indicates the significant potential of this concept for large-scale commercial electrochemical supercapacitor applications.

The modification techniques of applying carbon coating on particle surface and doping vanadium at Fe site were applied to make the LiFePO4 cathode materials achieve high rate performance in lithium ion batteries. To design and synthesize these LiFe(1−x)VxPO4/C (x = 0, 0.02, 0.05, or 0.08) composites, an aqueous solution–evaporation method was taken, in which every kind of raw material was distributed at a high degree of uniformity. The LiFe0.95V0.05PO4/2.57 wt% C composite displayed the best electrochemical performances. At rates of 0.1, 0.5, 2, 5, and 10 C (1 C = 170 mAg−1), it delivered a discharge capacity of 157.8, 156.9, 149, 139.6, and 130.1 mAh g−1, respectively. The composite exhibited perfect cycle stabilities as well, maintaining 100 % (0.5 C), 99.7 % (2 C), 98.9 % (5 C), and 96.6 % (10 C) of the first discharge capacity after 100 cycles at different rates, respectively.

The solubility data of lithium bis(oxalate)borate (LiBOB) were measured in six different solvents using the synthetic method and laser monitoring technique at temperatures ranging from (293.15 to 363.15) K under atmospheric pressure. The experimental solubilities of LiBOB in different solvents were correlated by the modified Apelblat equations. It is found the calculated solubility data show good consistency with the experimental values. On this basis, some thermodynamic parameters of LiBOB in different solvents, such as dissolution enthalpy, dissolution entropy, and dissolution Gibbs free energy, are also calculated. These results concerning the solubility of LiBOB in different solvents will provide fundamental data in the commercial application of LiBOB.

•Synthesis of Ce-doped Li3V2(PO4)3/C cathode by microwave sol–gel route.•At 1C, the Ce-doped cathode delivers a stable capacity of ∼170 mAh g−1.•At 10C, the Ce-doped cathode delivers a stable capacity of ∼120 mAh g−1.In this paper, a series of Ce-doped Li3V2(PO4)3/C composite cathode materials for Li-ion batteries were synthesized by a facile and fast microwave assisted sol–gel route. The investigation of the influence of Ce doping on the structural and electrochemical characteristics of Li3V2(PO4)3/C shows that the resulting composite exhibits smaller particle size, lower electron-transfer resistance, and faster lithium ion migration, which are attributed to improved lithium ion transfer by the Ce doping. At low charge/discharge rates, the Ce-doped Li3V1.98Ce0.02(PO4)3/C composite delivers a stable specific capacity of ∼170 mAh g−1 for over 100 cycles. At high rates (e.g. 10C), the Ce-doped composite is still able to deliver stable capacities of up to ∼120 mAh g−1 which is ∼60% greater than its un-doped counterpart.

One of the primary challenges in the development of a breakthrough lithium ion battery technology is to identify a composition that can effectively provide high power densities as well as high energy densities. Conventional graphitic anodes are considerably limited in this regard, owing to a limited charge storage capacity and constrained ionic and electrical conductivity. In this work, we report the use of a facile, scalable and low-cost Far Infrared (FIR) reduction strategy for the synthesis of graphene anodes as an alternative to conventional graphitic anodes. FIR irradiation was found to effectively reduce graphene oxide to graphene in under 3 min and displayed exceptional charge/discharge rates and charge storage capacities when used as an anode in lithium ion batteries. The binder-free FIR graphene anodes provided a very high reversible capacity of ~1016 mA h/g at a C-rate of ~1 C. Further, the FIR-reduced graphene anodes displayed impressive rate capabilities, delivering remarkably steady capacities as high as ~181 mA h/g at a C-rate of ~40 C over 1000 charge/discharge cycles, corresponding to an average power density of ~14 kW/kg.