Cycle-Life and Storage Tests of Lithium-Ion Secondary Cells with and without Additive in Electrolyte Solution

Abstract

Two 7.5 Ah lithium-ion secondary cells were fabricated with the same design of electrodes and separator. One cell had the mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) as an electrolyte solution containing vinylene carbonate as an additive to control the solid electrolyte interphace, while the other cell used a conventional electrolyte solution. These cells were used in cycle-life and storage tests and the increases in their impedances were monitored. The activation energy calculated from the temperature dependence of the impedance remained constant after 1,000 h. It was found that the additive like vinylene carbonate do not influence to the activation energy as a function of time for the electrochemical reaction inside the cell.