Meaning
Instability in the protective surface film on an anode leads to a gradual change in its resistance and lithium content. The solid electrolyte interphase drift describes the slow thickening or chemical evolution of the passivation layer over many cycles. This process continuously consumes active lithium and increases the impedance of the cell.
Growth Mechanism
New layers of the film form as the electrolyte decomposes on the anode surface. This solid electrolyte interphase drift is often accelerated by high temperatures or large mechanical strains. As the layer grows, it becomes harder for lithium ions to move through it.
Performance Decline
The result is a steady loss of capacity and a decrease in the power capability of the battery. Monitoring the rate of solid electrolyte interphase drift helps in predicting the total cycle life of the system. In many lithium-ion chemistries, this is the primary mechanism for long-term aging.
Measurement Method
Resistance increases measured at a specific state of charge often indicate the progress of this change. Sophisticated models use voltage data to separate this effect from other degradation types. Minimizing solid electrolyte interphase drift is the main purpose of most electrolyte additives.
Surface analysis techniques like electron microscopy confirm the chemical nature of the drifting layer.
