The degradation of lithium-ion battery life is also related to the way it is used and the environment in which it is used.
1. How to use
The most important factor is the charging and discharging rate of lithium-ion batteries. The standard charging and discharging rate for lithium-ion batteries is 0.2C. If the charging and discharging current is too high, the lifespan of the lithium-ion battery will be reduced faster! For example, 1C charging will reduce the lifespan faster than 0.2C charging, and 2C discharging will reduce the lifespan faster than 0.5C discharging.
Inconsistency issues can also accelerate the degradation of lithium-ion battery packs; the worse the consistency, the faster the battery pack will degrade. Consistency includes factors such as voltage, capacity, internal resistance, and self-discharge of lithium-ion batteries. Therefore, it is essential to ensure that lithium-ion batteries connected in series and parallel have similar performance to maximize the lifespan of the battery pack.
Furthermore, the more lithium-ion batteries connected in series and parallel, the worse the consistency will be. For example, a 72V lithium-ion battery pack with 20 cells in series will have worse consistency than a 12V lithium-ion battery pack with 3 cells in series. Therefore, the lifespan of a 72V lithium-ion battery pack will also degrade faster.
2. The environment in which it is used
The operating environment for lithium-ion batteries includes ambient temperature and humidity. The standard charging and discharging temperature for lithium-ion batteries is 25°C, with a charging operating temperature range of 0~45°C and a discharging operating temperature range of -20~65°C. The relative humidity is 45%～65%RH.
If lithium-ion batteries are charged, discharged, or stored in environments with excessively high or low temperatures, their lifespan will be reduced more rapidly.
Charging, discharging, or storing lithium-ion batteries in environments with excessively high or low humidity can accelerate rusting and thus affect their lifespan.
Inconsistent internal resistance, especially polarization resistance, in lithium-ion batteries causes drastic voltage changes in individual cells during charging and discharging, which in turn leads to drastic changes in the voltage of the entire lithium-ion battery pack.
Inconsistent voltages in individual ultra-thin lithium-ion battery cells will affect the peak-shaving capability of the battery pack, resulting in a reduction in the overall energy output of the battery pack.
Because ultra-thin batteries undergo heat release and absorption processes during operation, the temperature of lithium-ion batteries constantly changes. Overheating can lead to performance degradation and safety hazards. In fact, recent fires in electric vehicles during operation and testing have been caused by inadequate overheat protection, resulting in battery overheating and fires. This applies not only to lithium manganese oxide batteries but also to lithium iron phosphate batteries.
Capacity is the most serious factor in battery life degradation. Inconsistent capacity causes two main performance problems: first, some lithium-ion batteries will be overcharged and over-discharged, leading to safety hazards such as combustion and explosion; second, low-capacity cells will stop working early, affecting the energy release of other cells in the entire ultra-thin battery pack, thus causing the entire lithium-ion battery pack to experience life degradation.
