Quantifying Solid Electrolyte Interphase Growth and Lithium Plating Thresholds
Quantifying solid electrolyte interphase growth and lithium plating thresholds requires parsing passivating solvent consumption from kinetic overpotentials.
Voltage Relaxation Stripping
Meaning
Electrochemical diagnostic techniques detect the presence of metallic lithium plated on the graphite anode surface after a fast-charging event. One such non-destructive method, known as voltage relaxation stripping, monitors the cell voltage during the rest period following charge termination. Sourcing teams specify these diagnostic tests to evaluate whether a cell is suffering from premature degradation during high-rate charging.
Relaxation Mechanism
Mixed potential behavior at the anode surface governs the voltage response of the cell. Plated metallic lithium and the underlying intercalated graphite establish different potentials, which creates a local electrochemical cell. This potential difference drives the re-intercalation or stripping of the plated lithium during the relaxation period.
The voltage relaxation stripping technique relies on the characteristic voltage plateau or inflection point that appears as the plated lithium is stripped away.
Analytical Protocol
Analyzing the voltage curve during the rest phase yields quantitative data on the plated lithium. The duration of the relaxation plateau is directly proportional to the amount of metallic lithium deposited on the anode surface. This diagnostic does not require expensive equipment or the destruction of the battery, making it highly suitable for high-volume testing.
Supplier Evaluation
Sourcing contracts often require suppliers to validate their fast-charge profiles using these relaxation measurements. Procurement teams compare the voltage relaxation curves from different cell batches to assess the manufacturing consistency of the anode active material. This verification prevents the deployment of cells that are highly prone to internal lithium deposition under commercial operation.