Meaning
Evaluation procedures quantify the degradation of cylindrical lithium-ion cells over repeated charge and discharge cycles. The 21700 life testing determines the retention of capacity and power density for a specific cell format measuring 21mm in diameter and 70mm in length. It identifies the end of life point, which is typically defined as 80 percent of the initial capacity.
Cycle Protocol
The schedule defines the current rate, temperature, depth of discharge and rest time applied to the unit. Continuous cycling reveals the rate of cathode degradation and anode side reactions. Standardized 21700 life testing ensures that performance data from different batches remains comparable.
Environmental chambers maintain precise control over these variables to simulate specific use cases like urban driving or stationary storage.
Failure Analysis
Destructive physical analysis occurs after the capacity falls below the required threshold. Technicians disassemble the cell to inspect for lithium plating or electrolyte depletion. This 21700 life testing step confirms whether internal mechanical stress or chemical changes caused the loss of function.
Degradation Rate
Mathematical models use the results to estimate the remaining useful life in a specific application. A linear decline suggests stable chemistry while a sudden drop indicates onset of rapid aging. Accurate 21700 life testing data informs the sizing of battery packs to account for future loss.
