Aging mechanism analysis and its impact on capacity loss of lithium ion batteries

In this paper, aging mechanism of lithium ion batteries and its impact on capacity loss is analyst in detail, based on the simplified electrochemical model. The internal aging mechanism of the battery is identified from the open circuit voltage curve. These aging behaviors which result in capacity loss are classified into four parts: capacity loss of positive and negative electrode, loss of lithium ion inventory, and total polarization potential increase. The positive and negative electrode active materials continuously decay during cycling; and the lithium ions circulating between the positive and negative electrodes are also consumed inevitably during the charging and discharging process; and the total polarization voltage of the battery increases significantly which makes the battery reach the charge and discharge cut-off points in advance; these all lead to the battery capacity drop. Find out these factors from identification can help us understand the battery aging state and ensure the safe use of the battery. The experiment shows the identification results can reflect the internal aging state of the battery very well.