Meaning
Differential capacity analysis techniques identify the specific voltage peak associated with the dissolution of plated metallic lithium from the anode surface during the discharge phase. The feature referred to as the dq/dv stripping peak indicates the presence of reversible lithium plating that occurred during previous fast charging cycles. Electroanalytical engineers use this measurement to detect non-destructive signs of anode degradation and lithium accumulation.
The analysis is conducted under controlled laboratory conditions using precise voltage and current monitoring equipment.
Electrochemical Origin
Metallic lithium plates on the graphite anode when the local potential drops below zero volts versus lithium during rapid charging. During the subsequent discharge cycle, this plated lithium is oxidized and returned to the ionic state before the graphite intercalates discharge. This dissolution creates a distinct feature in the differential capacity curve at a specific voltage.
The magnitude of this feature correlates with the amount of reversible lithium that has plated on the electrode surface. Technicians use this correlation to quantify the severity of the plating process and evaluate the health of the electrode.
Diagnostic Method
High-resolution cycling data is collected during low-current discharge steps to ensure the resolution of the electrochemical features. The derivative of capacity with respect to voltage is calculated and plotted against the cell voltage to highlight the transition points. This derivative curve displays a clear peak that corresponds to the stripping of the plated lithium.
Charging Optimization
Charging algorithms are adjusted based on the presence and intensity of this peak to prevent irreversible capacity loss and dendrite formation. If the peak is detected, the fast-charging currents are reduced at lower temperatures to protect the anode. This adaptive charging strategy increases the lifespan of the battery and reduces the risk of internal short circuits.
Sourcing teams use this data to verify the low-temperature charging claims of cell suppliers. This optimization ensures the safe operation of high-performance energy storage systems.
