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Abstract: A high performance Li3V2(PO4)3 cathode material for lithium ion batteries was synthesized by the microwave-assisted hydrothermal method followed by a post annealing process. The synchrotron X-ray diffraction analysis results confirmed that single-phase Li3V2(PO4)3 with monoclinic structure was obtained. Scanning electron microscope and transmission electron microscope images revealed that the as-prepared Li3V2(PO4)3 was composed of nanowires and microsized particles. Electrochemical results demonstrated that the Li3V2(PO4)3 electrode measured at 10 C after 500 cycles can deliver discharge capacities of 85.4 mAh g−1 and 103.4 mAh g−1, with a capacity retention of 99.3% and 95.9%, in the voltage ranges of 3.0–4.3 V and 3.0–4.8 V, respectively, indicating good cycling stability. Furthermore, the electrochemical performance of Li3V2(PO4)3 in ionic liquid electrolytes between 3.0 V and 4.8 V was also measured. [Copyright &y& Elsevier]

Abstract: To overcome the problems of vanadium dissolution and the higher charge transfer resistance that results from it, VO2/graphene composite has been synthesized by an in-situ hydrothermal process directly from graphene oxide and V2O5, and characterized by X-ray diffraction, Raman spectroscopy, FT-IR spectroscopy, thermogravimetric analysis, atomic force microscope, and field emission scanning electron microscopy. Electrochemical tests show that the VO2/graphene composite features high discharge capacity (380 mAh g−1) and 99% capacity retention after 50 cycles. It has very low resistance, only 67% of that of pure VO2, indicating the enhancement of electronic conductivity. Carbon dispersed in the electrode material can provide a pathway for electron transport, resulting in improvement of the electronic conductivity. Graphene woven VO2 nanoribbons prevent the agglomeration of VO2 nanoribbons, meanwhile graphene and the VO2 nanoribbons together form a porous network in the random hybrid composite that can be filled with electrolyte, resulting in superior performance and enhanced reversible capacity in comparison with the pure VO2. Thus, this work provides a facile route to synthesize VO2/graphene composite which shows excellent electrochemical performance and is a potential material for lithium ion battery. [Copyright &y& Elsevier]

Abstract: LiNi1/3Mn1/3Co1/3O2 (NMC) as a cathode material for lithium ion batteries has been synthesized by the sol–gel method. The X-ray diffraction Rietveld refinement results indicated that single-phase NMC with hexagonal layered structure was obtained. Scanning electron microscope images revealed well crystallized NMC with uniform particle size in the range of 100–200 nm. The performance of the NMC electrodes with sodium carboxylmethyl cellulose (CMC), poly(vinylidene fluoride) (PVDF), and alginate from brown algae as binders was compared. Constant current charge–discharge test results demonstrated that the NMC electrode using CMC as binder had the highest rate capability, followed by those using alginate and PVDF binders, respectively. Electrochemical impedance spectroscopy test results showed that the electrode using CMC as the binder had lower charge transfer resistance and lower apparent activation energy than the electrodes using alginate and PVDF as the binders. The apparent activation energies of NMC electrodes using CMC, alginate, and PVDF as binders were calculated to be 27.4 kJ mol−1, 33.7 kJ mol−1, and 36 kJ mol−1, respectively. [Copyright &y& Elsevier]

Abstract: Porous Co3O4 nanostructured thin films are electrodeposited by controlling the concentration of Co(NO3)2 aqueous solution on nickel sheets, and then sintered at 300°C for 3h. The as-prepared thin films are characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The electrochemical measurements show that the highly porous Co3O4 thin film with the highest electrochemically active specific surface area (68.64m2 g−1) yields the best electrochemical performance compared with another, less-porous film and with a non-porous film. The highest specific capacity (513mAhg−1 after 50 cycles) is obtained from the thinnest film with Co3O4 loaded at rate of 0.05mgcm−2. The present research demonstrates that electrode morphology is one of the crucial factors that affect the electrochemical properties of electrodes. [Copyright &y& Elsevier]

Abstract: LiV3O8–polyaniline nanocomposites have been synthesized via chemical oxidative polymerization directed by the anionic surfactant sodium dodecyl benzene sulfate. The polyaniline particles are uniformly coated on the LiV3O8 nanorods. The composite with 12 wt.% polyaniline retains a discharge capacity of 204 mAh g−1 after 100 cycles and had better rate capability (175 mAh g−1 at 2 C and 145 mAh g−1 at 4 C) than the bare LiV3O8 electrode in the potential range of 1.5–4.0 V. The polyaniline coating can buffer the dissolution into the LiPF6 electrode that occurs in LiV3O8 during cycling. The charge transfer resistance of the composite electrode was much lower than that of the bare LiV3O8 electrode, indicating that polyaniline coating significantly increases the electrical conductivity between the LiV3O8 nanorods. Polyaniline is a conductive binder which buffers the dissolution of LiV3O8 into the electrolyte and reduces the contact resistance among nanorods, so performance of the composite is significantly improved. [Copyright &y& Elsevier]