Meaning
Differentiating voltage with respect to capacity transforms subtle electrochemical potential plateaus into identifiable peaks corresponding to phase transitions in battery electrodes. Analysts apply differential voltage analysis to diagnose active lithium loss and impedance growth without destructive cell teardowns. This analytical mathematical transformation applies during low C-rate galvanostatic cycling and stops where rapid dynamic polarization masks equilibrium thermodynamics.
Peak Resolution
Plotting dV/dQ against capacity reveals distinct features linked to lithium insertion chemistry. Sharp features correlate with coexistence regions of two intercalation phases within the host crystal lattice. Phase shift magnitudes indicate structural changes inside active materials.
Degradation Tracking
Over extended cycling, peak height attenuation identifies active material loss resulting from particle cracking or isolation. Peak position shifts along the capacity axis measure net active lithium consumption caused by solid electrolyte interphase formation. Comparing derivative profiles across charge and discharge cycles separates thermodynamic losses from kinetic voltage penalties.
Mathematical peak fitting allows quantitative tracking of individual electrode capacity retention throughout life testing.
Data Processing
Low-noise voltage measurements require high-resolution analog converters operating at stable temperatures during test routines. Raw voltage data undergoes mathematical smoothing using moving average or Savitzky-Golay filters to remove high-frequency noise before differentiation. Noise suppression preserves true peak shapes required for accurate parameter extraction.
