Meaning
Electrochemical signal observed during voltammetry measurements indicates the dissolution of metallic lithium previously plated onto the anode surface. This characteristic signal is known as the stripping peak, and it is used by battery researchers to detect and quantify the occurrence of lithium plating. The height and position of this voltammetric signal correspond directly to the amount of metallic lithium that can be electrochemically recovered.
It serves as a diagnostic tool to evaluate the safety and degradation of cells subjected to fast charging.
Diagnostic Method
Voltammetry techniques apply a controlled potential sweep to the cell while measuring the resulting current response. When the potential reaches the oxidation point of metallic lithium, the metal dissolves back into the electrolyte, creating a distinct current surge. Analyzing the area under this current curve allows engineers to calculate the mass of the plated metal.
This quantitative measurement is used to optimize charging profiles and prevent dendrite growth.
Plating Detection
Detecting the onset of lithium plating is critical for preventing the formation of hazardous metallic dendrites. The appearance of the current signal confirms that the charging rate or temperature has exceeded the safe operating limits of the cell. This information is used to update the battery management system algorithms, ensuring that the charging currents are reduced under cold conditions.
The diagnostic method provides a clear boundary between safe intercalation and harmful plating.
Cell Degradation
Repeated plating and stripping cycles lead to capacity fade because not all of the plated lithium can be recovered. A portion of the metal becomes electrically isolated and remains in the cell as dead lithium, permanently reducing the active capacity. By monitoring the changes in the current signal over many cycles, engineers can track the rate of active material loss.
This tracking is essential for predicting the remaining useful life of the battery pack.
