Abstract:

Lithium deposition reactions of lithium-ion batteries under different conditions are studied using three-electrode batteries. The corresponding material characterization is performed using X-ray diffraction (XRD) and atomic absorption spectrophotometry (AAS). Considering the changes in the electrode potential of low negative to positive ratio (N/P) batteries and low-temperature charging batteries during charging and discharging processes, the results show that once the lithium deposition reaction occurs, an additional potential plateau appears around 0 V during the charging process, and another additional potential plateau appears around 0 V during the next discharging process. The pair of additional potential plateaus that appeared around 0 V during the charging and discharging processes can be used as the criteria for the formation and stripping of lithium dendrite, expressed as Li⁺ + e^- ? Li. In addition, because the potential plateaus are referred to as the phase transitions in the electrodes, the proportion of reversible and irreversible lithium can be quantitatively analyzed using the corresponding charging or discharging time of the potential plateaus and the corresponding current. Furthermore, it is demonstrated that part of the deposited lithium on the anode surface can reinsert into the graphite layer during the next relaxation process at room temperature. The main reason is that concentration cells are formed between the deposited lithium and the graphite bulk, and partial discharge occurs during shelving, causing some of the deposited lithium to reinsert into the graphite layer. This work provides a quantitative analysis method for the lithium deposition reaction. It can be used as an experimental basis to predict the occurrence of lithium dendrites, which has a certain significance for the failure processes.

Key words: lithium-ion batteries, lithium deposition reaction, three-electrode batteries, the anode potential plateaus