I. Basumallick

Electrochemical studies on Li + /K + ion exchange behaviour in K4Fe(CN)6 cathode material for Li, K-ion battery

AbstractThe electrochemical studies of anhydrous K4Fe(CN)6 is reported. Anhydrous material was produced after dehydrating K4Fe(CN)6.3H2O crystal at 200°C in an open atmosphere. The material, as obtained, was characterized by various spectroscopic techniques, such as UV-Visible, FTIR, powder X-ray diffraction and FESEM-EDX. Electrochemical and Li+/K+ ion exchange behaviour of the synthesized material were studied by cyclic voltametry (CV), chronoamperometry (CA) and galvanostatic charge-discharge method after preparing a laboratory model cell against lithium anode instead of potassium. During anodic scan in the 1st cycle, peak maximum was observed at 3.93 V vs. Li+/Li due to removal of K+ ions from the ferrocyanide matrix, whereas, in the reverse scan (cathodic sweep) as well as in consequent cycles, peak maxima due to Li+ ion insertion and extraction were observed at 2.46 V and 3.23 V vs. Li+/Li, respectively. Cell, assembled using ferrocyanide cathode and lithium anode, shows an open circuit potential of 3.08 V and delivers a maximum capacity of 61 mAh g−1 (theoretical capacity 72 mAh g−1) at a rate of 0.2 C at room temperature. Graphical AbstractHighly dispersed crystalline K4Fe(CN)6 has been synthesized by simple cost effective route. The material was charge-discharged using lithium-salt electrolyte against Li metal. The redox peak current increment, shift of peak position in CV and capacity enhancement during charge-discharge cycles were explained in terms of faster exchange rate of K+ by Li+ ion.

Fabrication and Characterization of Nano Electrocatalyst (Pt) for Methanol Electro Oxidation

Nanosized platinum catalysts were deposited onto graphite and carbon felt surface by both chemical and electrochemical techniques. The controlled potentiostatic condition was used for electrodeposition using cationic surfactant, CTAB, at pre-CMC concentration in electrolytic bath. Electrocatalytic activity of such electrodes for methanol oxidation were studied and compared. The parameters like peak potential (Ep), peak current (ip), apparent diffusion coefficient for methanol (Dapp), Tafel slope and apparent rate constant (k) were obtained from cyclic voltammograms of methanol oxidation in acid medium. The morphology and crystal structure of these electrodes were analyzed by SEM and XRD. Electrokinetic parameters of these systems clearly indicate that methanol oxidation rates are almost comparable onto these electrodes. It is thus suggested to follow electrochemical route using surfactant as capping agent. Graphites are found to be better substrate than felt material. SEM pictures clearly indicate formation of highly dispersed catalytic particles (Pt) via electrochemical route.