Preface Formation is a critical step in the production process of lithium-ion batteries. The primary purpose of formation is to generate a solid electrolyte interphase (SEI) on the surface of the anode, which serves to isolate electrons while allowing ion conduction. The quality of the SEI formation directly affects the subsequent cycling performance of the battery. Therefore, controlling appropriate formation conditions (such as formation temperature, charging rate, applied pressure, etc.) is a crucial production step. The SEI formation process is accompanied by an increase in the volume of the battery. This increase is attributable to two main factors: the gaseous byproducts generated during the film formation reaction and the expansion of the anode structure as lithium ions are extracted from the cathode and intercalate into the anode. In this study, in-situ volume monitoring instruments (GVM) are employed to conduct in-situ volume testing of NCM523/graphite cells (theoretic...
The formation process is an indispensable step in the manufacturing of lithium-ion batteries, as it directly affects the battery’s performance, safety, and lifespan. One of the key roles during the formation process is the formation of a stable solid electrolyte interphase (SEI) film on the surface of the anode. The SEI film protects the anode material from further erosion by the electrolyte, preventing the dissolution of the anode material in the electrolyte and thus extending the battery’s lifespan. At the same time, a stable SEI film can prevent the continuous decomposition of the electrolyte during subsequent charging and discharging cycles, reducing internal side reactions and thereby minimizing performance degradation. The formation process of lithium batteries is divided into four steps: open-circuit charging, closed-circuit charging, closed-circuit aging, and closed-circuit discharging. 1.Open-Circuit Charging (Pre-charging or Gas Venting) This step primarily involves charging ...