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Abstract: γ-MnO2 has been synthesized by hydrothermal process, and studied as electrode material in aqueous asymmetric super-capacitor. We studied the blend formed by electrochemical polymerization of pyrrole deposited onto γ-MnO2 particles. The composite materials (PPy/MnO2) were characterized by different methods including cyclic voltammetry, chronoamperometry, X-ray diffractometry and BET measurements. The specific capacitance at constant current density 2 mA cm−2 was calculated from galvanostatic charge-discharge cycling tests. The asymmetric super-capacitor using (PPy/MnO2) composite material has high specific capacitance of 141.6 F g−1 compared with 73.7 F g−1 for γ-MnO2 before PPy coating. The improvement of the coating is not only due to the electronic conductivity of the polymer, but also due to an increase of the BET surface area that raises to 125 m2 g−1 after coating, against 64 m2 g−1 for pristine MnO2. [Copyright &y& Elsevier]

Abstract: Ni3Sn2 and several Co–Sn alloys prepared by electrodeposition in molten LiCl–KCl were studied as anode materials in rechargeable Li-ion battery. In the case of Ni3Sn2, the charge–discharge curves do not exhibit any plateau in contrast with Co–Sn alloys. For Ni3Sn2, the reversible capacity and the coulombic efficiency tend to constant values of about 225mAh/g and 85%, respectively, after subsequent cycles. Among the studied Co–Sn alloys, the best electrochemical performances was observed when CoSn2 was used as anode material: the reversible capacity and the coulombic efficiency observed after 60 cycles were about 530mAh/g and 96%, respectively. Whatever the alloys, SEM investigations performed before and after cycling do not reveal any significant difference between the original material and the cycled material, indicating a good stability of the electrodeposited films upon cycling. [Copyright &y& Elsevier]

Abstract: Co–Sn alloys were prepared by an electrochemical route in molten LiCl–KCl between 400 and 550°C. The Sn(IV)/Sn(II), Sn(II)/Sn(0) and Co(II)/Co(0) redox couples were studied by cyclic voltammetry and/or chronopotentiometry over the temperature range. The diffusion coefficient values of Co(II) ions were measured. For example, it was found that the D Co(II) values deduced from chronopotentiometry range from D Co(II) =1.65×10−5 cm2 s−1 at 400°C to 4.95×10−5 cm2 s−1 at 550°C. The standard potential of the Co(II)/Co(0) redox couple in molten LiCl–KCl was measured at 400°C: vs Cl2/Cl−. Finally, Co–Sn alloys were prepared in potentiostatic mode. The influence of the temperature of molten LiCl–KCl, the applied potential and the deposition time on the morphology and the composition of the Co–Sn alloys were also investigated. For T >450°C, the following tendency has been observed: the more negative the potential, the higher the Sn content in the deposited alloy. Thus, depending on the operating conditions, pure CoSn or CoSn2 can be prepared. [Copyright &y& Elsevier]

Abstract: Improvements of the electrochemical features of CF x cathode materials in primary lithium battery were obtained by the electrodeposition of polypyrrole (PPy) performed in acetonitrile with Py monomer. The electrodeposition does not affect the core of the CF x powder as revealed by XRD and TEM. The maximum discharge rate which is 1C for pristine CF x increases for PPy–CF x and reaches 4C in the case of PPy–CF0.80 1M LiPF6–EC:DMC (1:1) electrolyte. A maximum power density of 5235W/kg (4C-rate) has been achieved with PPy–CF0.80, a value around 3.8 times higher than for CF0.80 (1C-rate). [Copyright &y& Elsevier]