Ma J.-L.,Harbin Institute of Technology |
Wang D.-L.,Harbin Institute of Technology |
Chen F.,Tianneng Group |
Fang M.-X.,Tianneng Group
Chinese Journal of Inorganic Chemistry | Year: 2013
Lead sulfate/graphene nano sheets (GNS) composites were fabricated by using a simple impregnation method. The composite was used as a negative active material for lead acid battery. Compared with pure lead sulfate electrodes, the composite electrodes display higher specific capacity and rechargeable performance under high charge and discharge rates. An average discharging specific capacity of PbSO4/GNS composites reaches 110, 94 and 69 mAh·g-1 at current density of 100 mA·g-1, 200 mA·g-1 and 300 mA·g-1, respectively. However, the average discharging capacity of PbSO4 only reaches 49, 5 and 0.5 mAh·g-1 at the same condition. The electrochemical characteristic of the composites electrode was studied by cyclic voltammetry (CV) and battery tests. The cyclic voltammetry results show that capacitive effect and the hydrogen evolution of graphene nano sheets become more obvious with the increase in scanning rate resulting in 20% lower charging efficiency of PbSO4/GNS composites compared to lead sulfate. The battery charge-discharge curves confirm that graphene nano sheets improve the charging voltage about 0.1 V and can also help double the capacity of lead sulfate. The XRD and SEM results show that lead sulfate particles are well dispersed on the surface of graphene nano sheets instead of agglomerating.
Zhang J.,South China Normal University |
Shu D.,South China Normal University |
Shu D.,Tianneng Group |
Shu D.,Power-battery |
And 9 more authors.
Journal of Alloys and Compounds | Year: 2012
Polyaniline (PANI) and manganese dioxide (MnO 2) composite (PANI/MnO 2) was synthesized via a simultaneous-oxidation route. In this route, all reactants were dispersed homogenously in precursor solution and existed as ions and molecules, and involved reactions of ions and molecules generating PANI and MnO 2 simultaneously. In this way, PANI molecule and MnO 2 molecule contact each other and arrange alternately in the composite. The inter-molecule contact improves the conductivity of the composite. The alternative arrangement of PANI molecules and MnO 2 molecules separating each other, and prevents the aggregation of PANI and cluster of MnO 2 so as to decrease the particle size of the composite. The morphology, structure, porous and capacitive properties are characterized by scanning electron microscopy, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, Branauer-Emmett-Teller test, thermogravimetric analysis, Fourier transform infrared spectroscopy, cyclic voltammetry, charge-discharge test and the electrochemical impedance measurements. The results show that MnO 2 is predominant in the PANI/MnO 2 composite and the composite exhibits larger specific surface area than pure MnO 2. The maximum specific capacitance of the composite electrode reaches up to 320 F/g by charge-discharge test, 1.56 times higher than that of MnO 2 (125 F/g). The specific capacitance retains approximately 84% of the initial value after 10,000 cycles, indicating the good cycle stability. © 2012 Elsevier B.V.
He W.,Tianneng Group |
He W.,Hefei University of Technology |
Chen Q.,Tianneng Group |
Zhang T.,Tianneng Group |
And 2 more authors.
Micro and Nano Letters | Year: 2015
A uniform precursor of Li3V2(PO4)3 nanoparticles was synthesised by a solvothermal method using ethanolamine lactate as both solvent and carbon sources at ambient pressure. Nanostructured Li3V2(PO4)3/C cathode materials could be successfully prepared by subsequent heat treatment. The scanning and transmission electron microscopy observation shows that the as-synthesised Li3V2(PO4)3/C powders retained the morphology and the particle size of the precursor that was formed during the solvothermal process. The Li3V2(PO4)3 particles are coated with uniform carbon layers with a thickness of about 5 nm. The material presents excellent performance with a high-rate capacity and cycle stability. It can deliver discharge capacities of 127.9, 117.7, 104.9 and 95.6 mAh g-1 in the potential ranges of 3.0-4.3 V, 164.0, 154.8, 141.0 and 131.1 mAh g-1 between 3.0 and 4.8 V corresponding to 0.5, 1, 5 and 10 C rate after cycles, respectively. The charge transfer impedance increases from 55.55 to 127.31 Ω after 50 cycles at 1.0 C, which is attributed to the refined structure and the uniform carbon film on the surface of the as-prepared Li3V2 (PO4)3/C powders. © The Institution of Engineering and Technology 2015.