Lithium-ion batteries, as the power source for new energy vehicles, are crucial to the vehicle's range. However, in actual use, various factors can cause battery degradation, much like electronic products. After prolonged use, they become less efficient and have lower capacity. To understand the reasons for lithium battery degradation, we must first examine the battery's operating condition.
Lithium-ion batteries primarily convert chemical energy into electrical energy through internal electrode oxidation reactions. The internal structure of a lithium-ion battery consists of positive and negative electrode materials and an electrolyte. When the battery is repeatedly charged and discharged, the internal electrochemical reaction causes crystals to form on the battery's electrode materials, leading to a decrease in the battery's internal conductivity. This means that the activity of lithium ions decreases, resulting in an increase in resistance and ultimately affecting the battery's capacity. In reality, factors affecting battery degradation include the charging and discharging voltage, the charging and discharging power, and the ambient temperature.
Currently, the main type of battery used in new energy vehicles is ternary lithium batteries. The biggest concern with ternary lithium batteries is their susceptibility to high environmental temperatures, which can affect their lifespan and energy density. In terms of the power output of electric vehicles, battery degradation is mainly due to the different charge and discharge rates used during vehicle operation to meet different driving conditions. The higher the charge and discharge rate, the faster the battery capacity decays. This is primarily due to changes in the structure and properties of the materials, making ion diffusion within the battery relatively difficult.
For batteries, inconsistent internal resistance leads to uneven current and voltage distribution, potentially causing undervoltage in individual cells. In summary, many factors affect the lifespan of power battery packs, and these factors interact with each other. The degradation of lithium-ion power batteries is currently unavoidable. As power battery technology continues to improve, addressing battery capacity degradation to extend battery lifespan is crucial. This is also vital for the development of electric vehicles.
