Generally speaking, when using lithium-ion batteries, we pay attention to certain technical specifications as important factors in evaluating their performance. So, what specifications should we pay special attention to when using them? Please read on.
1. Capacity
Capacity is generally measured in mAh or Ah, and there is a difference between rated capacity and actual capacity in use. Rated capacity refers to the total amount of electricity a fully charged lithium-ion battery can supply when discharged to the cutoff voltage at a specific discharge rate under laboratory conditions. Actual capacity is generally not equal to rated capacity, and it is directly related to temperature, humidity, charge/discharge rate, etc. Under normal circumstances, the actual capacity is slightly smaller than the rated capacity, and sometimes even much smaller. For example, in northern winters, if a mobile phone is used outdoors, the battery capacity will drop rapidly.
2. Energy density
Energy density refers to the amount of electricity a battery can store and release per unit volume or weight. It is measured in two units: Wh/kg and Wh/L, representing specific energy at weight and specific energy at volume, respectively. The amount of electricity here is the integral of the capacity (Ah) and operating voltage (V), as mentioned above. In applications, energy density is a more instructive indicator than capacity.
The improvement of energy density in lithium-ion batteries is a slow process, far slower than Moore's Law in the integrated circuit industry. This creates a gap between the performance improvement of electronic products and the improvement of battery energy density, and this gap continues to widen over time.
3. Charge/discharge rate
This indicator affects the continuous current and peak current of a lithium-ion battery during operation, and its unit is generally C. Multiplying the current value corresponding to the charge/discharge rate by the operating voltage yields the continuous power and peak power specifications of the lithium-ion battery.
The more detailed the meaning of charge/discharge rate specifications, the greater their guiding significance for use. This is especially true for lithium-ion batteries, which serve as power sources for electric vehicles; it is essential to specify continuous and pulse rate specifications under different temperature conditions to ensure that lithium-ion batteries are used within reasonable limits.
