| This paper covers two parts. The first part reported Mn(III)/Mn(II) couple was used to be the cathode in a redox flow cell. The second one studied tin-based materials for anodes in lithium-ion batteries.The potential of Mn(III)/Mn(II) redox couple in H2SO4 is 1.51V vs.NHE, which may be suitable for the positive half-cell in a redox flow storage system. But studies on this couple as a positive electrode in this system have not been reported so far. In the first part of this paper, Mn(III)/Mn(II) couple in H2SO4 was firstly applied as the positive couple to this system, i.e. redox flow cell. Its chemical, electrochemical properties, redox kinetics and related parameters were characterized and discussed by rotating disc electrode (RDE), cyclic voltammetry (CV), a.c.impedance (A.C.Imp), chronoamperometry, tafel curve, and galvanostatic charge/discharge techniques. Conclusions have been drawn as follows:1.The electrochemical kinetics of Mn(III)/Mn(II) redox couple in 6.3M H2SO4 solution were studied by means of rotating disc electrode (RDE) technique on platinum electrode. The experiment results showed that electron transfer and/or mass transport become the rate-determining step for the electrode process depending on the magnitude of the overpotential and the rotating speed of RDE. And the kinetic parameters of Mn(III)/Mn(II) redox process were calculated to be ks=1.771×10-4cm·s-1 , io=4.801mA·cm-2 and α=0.234. The value of ks is sufficient to warrant further study to improve the reaction rate and to assess the feasibility of this couple as positive half-cell in a redox-cell system.2.Redox behaviors of Mn(III)/Mn(II) couple on static platinum electrode in H2SO4 were investigated by cyclic voltammetry with the change of Mn(II) concentration, acid concentration, scan rate, temperature and convection. It was demonstrated that the redox process of Mn(III)/Mn(II) was a simple one-electron, and pseudo-reversible reaction between Mn(II) and Mn(III). The electrochemical kinetics of Mn(III)/Mn(II) on static Pt electrode was mass transfer controlled. Increasing acid concentration and Mn(II) concentration favors the stability of Mn(III), i.e. inhibit the disproportionation and hydrolysis of Mn(III). Higher temperature and stirring enhanced the redox rate of Mn(III)/Mn(II).3.The electrochemical behaviors of Mn(III)/Mn(II) redox couple were studied through cyclic voltammetry, a.c.impedance, and galvanostatic charge/discharge techniques on three different graphite electrodes respectively. The results indicated that the electrochemical reversibility and charge/discharge efficiency on spectral pure graphite electrode are superior to that on the other two, and the possible causes of these differences are presented. First, it is associated with the prepared conditions of spectral pure graphite electrode; second, compared with the untreated graphite, the surface functional groups of —OH and —COOH on the treated one increased dramatically with hot concentrated H2SO4 and the impurities on electrode surface decreased significantly with ultrasonic rinse. A sequence reaction mechanism was proposed for the EIS of Mn(Ⅲ)/Mn(Ⅱ) on different graphite electrodes. The spectral graphite and the treated one can be suitable for the inert electrode of Mn(Ⅲ)/Mn(Ⅱ) cathode.4.Through the galvanostatic charge/discharge experiments with different schedules, it was found that Mn(Ⅲ)/Mn(Ⅱ) in acidic media as half-cell in a novel redox flow system is practically feasible in that it has such advantages as low cost, high open voltage, a certain coulombic efficiency with low charge/discharge current, and long cycling life.In the second part, CoSn alloy and Cu-Sn samples were synthesized firstly by H2-reduction following solid-state reaction between Co(II),Cu(II),Sn(IV),and NaOH at ambient temperature. And Cu6Sn5 alloy were synthesized by chemical reduction between Cu(II), Sn(IV) and Zn. Samples were characterized by XRD, SEM and TEM. The results showed that B sample was globe-shaped, ultra-fine hexagonal CoSn alloy (80~200nm) an...
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