Study of electrochemical performance of LiFePO4 and graphite electrodes with EC/DMC electrolyte in Li-ion batteries

The demand for reachargeable batteries with longer cycle-lives and higher performance for modern electrical devices has been increasingly developed. For many years, these needs havebeen met by variants of the lithium-ion battery that has been first commercialized by Sony [1].Recently, LiFePO4 has been investigated intensively as a potential cathode material for rechargeable Li-ion batteries because of its low cost and improved safety [2-5]. The performanceof industrial electrodes, lithium iron (II) phosphate, LiFePO4, as a cathode material and graphite as an anode in a lithium secondary battery was evaluated using conventional electrochemical analyses such as cyclic voltammetry, charge-discharge profile, and Electrochemical ImpedanceSpectroscopy (EIS). Both anode and cathode materials were tested in half cell separately versus Li/Li+ as reference electrode. A conventional solvent such as ethylene carbonate and dimethyl carbonate (EC/DMC; 1:1 v/v %) with 1M LiPF6 were used in all tests. The EIS measurementsshowed an eligible resistance value for both anode and cathode electrodes. CV studies of these system were also done in which the peak current was not noticeably changed during first cycles.Half wave potential and the intensity of peaks confirmed the mechanism of insertion/deletion oflithium into working electrode as redox mechanism in LIB’s. The specific capacity and cyclic stability were also investigated at 0.1 C-rates, at room temperature. The discharge capacity at 1st cycle and the cycleability during 25 cycles were studied. The discharge capacity and cycleability were comparable with current values of LiFePO4 and graphite based electrodes.

کلیدواژه ها:

Lithium-ion batteries ، LiFePO4 ، Graphite ، discharge capacity ، and cycleability