Video explanation
Changing charge rate and temperature moves the graphite surface from intercalation toward metallic lithium deposition, followed by partial recovery during rest.
Intercalation or deposition
Normal charging inserts lithium into graphite. When insertion cannot keep up, metallic lithium may deposit at the surface as a competing reaction.
Fast charge and cold
High current increases polarization, while cold slows transport and reactions. Both can increase plating risk.
Recovery is incomplete
Some deposited lithium can re-enter graphite during rest, but inactive lithium and side reactions still cause losses. Voltage readouts refer to a lithium reference in the model.