Impact of low temperature and charge profile on the aging of lithium-ion battery: Non-invasive and post-mortem analysis

Abstract

In this paper, the low temperature performance of lithium-ion batteries under various charge rates ranged from 0.2 C to 1 C were studied. To shed some light on the degradation modes and aging mechanism, non-invasive and post-mortem analysis were adopted. The results reveal that there is a considerable reversible capacity loss and internal resistance increase with the increase in charge rate. Particularly, the relative capacity of 1C charged cell after 150 cycles is below 0.8, indicating the end of life is achieved. In addition, the increased internal resistance will lead to a substantial increase in heat generation rate, which is an important factor to the thermal safety control of battery related to the design of thermal management strategy. Besides the resistance increase, two major degradation modes i.e., loss of lithium inventory and loss of active material are demonstrated according to the differential voltage and incremental capacity analysis. It is found that lithium plating is regarded as the main aging mechanism. The anode material of cycled cell display distinct deterioration even exfoliated from the copper foil upon a macroscopic check, and a thick deposited layer morphology and cracking of the layer is visible from a micro point of view through cell opening. During the low temperature charging, lithium plating could be triggered due to the limitation of charge transfer resulted from high-rate charge as well as the limitation of solid-state diffusion resulted from low temperature. The continuous lithium-consuming during cycling will lead to secondary SEI formation, which may result in dead lithium and stripping, eventually reversible capacity loss.