Electrochemistry of Disulfide Compounds: I . Electrochemical Polymerization‐Depolymerization Process of 2,5‐Dimercapt‐1,3,4‐thiadiazole

Abstract

The electrochemical polymerization‐depolymerization of an organodisulfide compound, 2,5‐dimercapt‐1,3,4‐thiadiazole (DMcT), was investigated under in situ conditions by quartz crystal microbalance (EQCM) and atomic force microscopy (AFM) measurements employed simultaneously with electrochemical voltammetry. The EQCM results, together with the cyclic voltammetric results, suggest that the polymerization and depolymerization processes of DMcT do not occur with the same coulombic efficiency. The number of electrons consumed during the polymerization process is greater than that for the depolymerization process, indicating that some other chemical process occurs at the same time. The EQCM analysis and AFM observations indicated that the oxidation of DMcT, especially at higher potentials, involves not only a straightforward polymerization process via S‐S bonds but also an overoxidation or degradation (decomposition) process of the poly(DMcT) deposited on the electrode surface. The AFM images of the deposited poly(DMcT) show smooth/uniform and isolated/island growth at low (0.8 V) and high (1.4 V) potentials, respectively. Substantial decomposition of poly(DMcT) was confirmed from both EQCM and AFM analysis when the polymer was formed at high potential (1.4 V). This behavior can be regarded as a serious drawback when the material is used as battery material.

A Review of Metal Oxide Composite Electrode Materials for Electrochemical Capacitors

“…17 The experimental speci¯c capacitance values of PANI, PPy and PEDOT are 240, 530 and 92, respectively. 69 66 With these reasons, three main approaches are proposed: (i) replacing electrode material with higher capacitance nanostructured carbon or pseudocapacitive materials, (ii) changing electrolyte by durable new electrolytes and (iii) developing hybrid cell con¯gurations. 67 In particular, exploring new hybrid energy storage systems have received a great deal of attention.…”

“…3, that the most widely investigated metal oxide is ruthenium oxide because of its excellent pseudocapacitive behavior, good reversibility and high conductivity. 29,66 However, the high cost of this precious metal oxide hinders its practical applications. Consequently, relatively low-cost materials such as MnO 2 25 In order to reduce the cost of materials while maintaining its high charge storage performance, extensive works have focused on the development of combining RuO 2 with carbonaceous materials to form bulk composite electrodes.…”

“…The reported speci¯c capacitances for both EDLCs and pseudocapacitors including metal oxides and conducting polymers in single or composite electrode materials. 66 69 It should be pointed out that, the capacitance increase with ruthenium loading is likely counterbalanced by a loss of rate capability. An increase in the ohmic voltage drop or ESR, with increase in RuO 2 loading is veri¯ed by galvanostatic charging-discharging measurements.…”

“…115 Following this work, other systems have been designed, coupling a negative lithiated compound to a positive AC at low voltage. 66 The nonaqueous asymmetric hybrid capacitors utilizing lithium-intercalated compounds (Li 4 116 These 500 F devices were made in the same technology as Li-ion batteries, demonstrating speci¯c energy of 11 Wh/kg in 2 M LiBF 4 . Additionally, the cycle-life of this lithiated electrode is more superior as compared to Li-ion batteries, approaching that of EC.…”

Cathodic Stripping Voltammetry of 2-Mercapto-5-Methyl-1,3,4-Thiadiazol and 2,5-Dimercapto-1,3,4-Thiadiazol at a Controlled-Growth Mercury Drop Electrode

“…Magee [4] chose DMTD as a new type of ligand in the determination of cadmium and zinc by adsorptive stripping voltammetry. Only in recent years has it been extensively studied as a cathode active material for rechargeable lithium batteries by Visco et al [5,6] and Oyama [7][8][9][10][11][12][13] et al…”