Meaning
Diagnostic mathematical derivatives transform charge-discharge curves into distinct voltage derivative peaks that reveal electrode thermodynamic state. The differential voltage analysis dv dq plots the derivative of cell voltage with respect to capacity against total capacity. This technique identifies individual electrode phase transitions and loss mechanisms without requiring three-electrode test cells.
Application covers full-cell aging characterization and stops short of non-destructive structural imaging.
Peak Identification
Derivative features correspond directly to phase coexistence regions within cathode and anode intercalation materials. Shifted peak positions under differential voltage analysis dv dq signal active material loss or lithium inventory loss across extended cycling. Reference electrode validation matches specific peak alignments to individual electrode potentials.
Algorithms extract these features from standard battery management system telemetry.
Degradation Tracking
Degradation analysis separates active lithium loss from active material isolation in aged cells. Accelerated degradation tracking through differential voltage analysis dv dq isolates solid electrolyte interphase growth from cathode dissolution during high temperature storage.
Quality Inspection
End of line testing uses brief partial cycles to compute derivative curves for manufacturing defect screening. Uneven coating thickness alters local phase transition signatures across the electrode sheet. Batch screening discards cells displaying anomalous peak broadening prior to module building.
