Abstract
Lithium plating is an important issue for lithium-ion battery safety and cycle life that can be caused by cycle at low temperature. In this study, we investigated battery aging over an extended low-temperature cycle and at high temperature after the low-temperature cycle. Nondestructive and destructive analysis methods were used to study battery electrochemical dynamics and changes to the materials, and the results indicated that battery aging over the extended low-temperature cycle could be divided into two stages. The mechanism of the first stage is that of "dead lithium," which causes significant capacity fading, whereas that of the second stage is solid electrolyte interphase (SEI) growth. It was also found that plated lithium accelerates battery aging at high temperature; part of it is intercalated into anode, another part of it reacts with the electrolyte, thus consuming the plated lithium. Thus, electrolyte decomposition and SEI growth are the primary aging mechanisms at high temperature after low-temperature cycling. The plated lithium content and charge/discharge rate affected plated lithium consumption during the high-temperature cycle. Plated lithium was not depleted for the battery with significant amounts of plated lithium or upon charging with high current and discharging with both high and low current when the state of health (SOH) decreased to 70%. The factors affecting battery aging ranked in order of importance are charge current > plated lithium content > high temperature > discharge current.