Dynamic Diagnostic Technique for Real-Time Detection Lithium Plating Using Electrochemical Harmonic Analysis

Lithium-ion batteries have transformed energy storage and are now integral to various applications, including electric vehicles. With the automotive industry increasingly demanding fast-charging capabilities, the potential risk of lithium plating during rapid charging presents a significant challenge. Hence, there is a pressing need for reliable and real time diagnostic methods to detect and address lithium plating issues. This study introduces an innovative technique, Real-time Electrochemical Harmonic Analysis (EHA), for dynamic analysis aimed at detecting the onset of lithium plating in lithium-ion batteries. EHA utilizes a unique combination of higher amplitude AC with the DC charging. The large sinusoidal current amplitudes facilitate the characterization of battery behaviour based on the harmonics derived from voltage outputs corresponding to the applied current inputs. The time-dependent variations in the sinusoidal output voltage are subjected to Fast Fourier Transformation (FFT) to obtain the harmonics. The proposed method predicts the generation of higher harmonics due to the inherently nonlinear processes within lithium-ion batteries, during the lithium plating event. The higher amplitude sinusoidal current provide a means to characterize battery behaviour by analysing harmonics derived from voltage outputs corresponding to the applied current inputs. These time-dependent variations in sinusoidal output voltage undergo Fast Fourier Transformation (FFT) to extract harmonics. The method proposed predicts the emergence of higher harmonics resulting from the inherent nonlinear processes within lithium-ion batteries, particularly during lithium plating events. This study specifically focuses on Y3 as an indicator of voltage response distortions due to the onset of lithium plating. The findings reveal that Y3 values, derived from signals in the 0.2 to 10 Hz frequency range and at 1–2C amplitude, exhibit high sensitivity in the plating region. Figure 1 illustrates the Y3 results during discharging of a hybrid cell where the cathode is composed of NMC cell anode material and the anode is lithium metal; in this context, discharging mirrors typical charging in conventional cells. It is widely acknowledged that the anode potential (here the hybrid cell voltage) drops below 0V where lithium plating is expected to occur and in Figure 1, we can observe a distinct change in the response of Y3 below 0V. These experimental findings underscore that monitoring harmonic responses during cell charging can effectively detect the early stages of lithium plating. Further validation tests are ongoing, supporting our proposal of Real-time Electrochemical Harmonic Analysis (EHA) as a promising and practical solution for enhancing the performance and safety of lithium-ion batteries in demanding applications. Figure 1