Meaning
Analytical procedures used to quantify the degradation of a cell while it remains at rest. Engineers use calendar aging diagnostics to distinguish between losses caused by cycling and those occurring naturally over time. These tests often involve high temperature storage to accelerate the formation of the solid electrolyte interphase.
Degradation Assessment
Periodic discharge tests provide the data for long term monitoring. Such analysis forms the degradation assessment of calendar aging diagnostics. Measuring the open circuit voltage at fixed intervals shows how internal resistance grows.
These data points allow for the projection of long term shelf life.
Storage Condition
Temperature and state of charge define the environment during the testing phase. These variables influence the storage condition of calendar aging diagnostics. Higher heat levels generally speed up the chemical breakdown of the electrolyte.
Keeping a cell at a full charge state increases the stress on the cathode lattice.
Capacity Retention
Calculating the difference between initial and final discharge energy determines the stability of the cell. This measurement defines the capacity retention of calendar aging diagnostics. A stable chemistry loses only a few percentage points of its energy per year under ideal conditions.
Frequent monitoring ensures that the product meets the warranty requirements of the end user and allows the manufacturer to refine the state of charge limits for long term storage.
