Quantifying Lithium Inventory Losses during Extended Calendar Aging Protocols
Extended calendar aging consumes cyclable lithium through solid electrolyte growth, requiring differential capacity verification before warranty assignment.
Capacity Fade Breakdown
Meaning
Analytical diagnosis technique quantifies the individual contributions of different degradation mechanisms to the total loss of discharge capacity in a lithium-ion cell over its operating life. Through a capacity fade breakdown, engineers isolate the loss of active material at the positive and negative electrodes from the loss of lithium inventory due to side reactions. Identifying these degradation modes is necessary for battery developers who must decide whether to modify the electrolyte composition or adjust the mechanical containment of the cell to prolong its life.
Electrochemical Mechanism
Loss of active material reduces the available sites for lithium insertion. When this occurs, the capacity fade breakdown typically shows a decrease in the peaks of the differential capacity curve. If the loss is driven by lithium consumption instead, the curves shift horizontally, showing that the electrodes can no longer be fully utilized.
Diagnostic Method
Incremental capacity analysis and differential voltage curves are used to generate these data points. These mathematical derivatives of the charge and discharge curves highlight the thermodynamic changes occurring inside the cell. Sourcing managers use the resulting breakdown reports to evaluate whether a cell chemistry is suitable for long-life storage applications.
Material Output
The diagnostic provides a clear breakdown of the degradation profile.