An Experimental Analysis on the Impacts of Current Pulsing with Varying Current Amplitudes on Lithium-Ion Cells

Abstract

Lithium-ion cells can be charged using different techniques. CCCV (constant current, constant voltage) charging is the standard method that is typically employed for charging the lithium ion batteries/cells. A theoretical analysis of pulse charging using varying current amplitudes with the relaxation periods has shown reduction in the charging time without reaching lithium saturation over the period [1]. It is based on the concept of increasing surface concentration of lithium at initial stages and maintaining the concentration value close to the saturation, resulting in enhanced performance. The objective of this work is to experimentally analyze the impacts of varying current pulse amplitudes on the lithium ion battery materials. This method comprises constant width charging, a rest period and decrease in applied current as the charging progress. Implementing the pulsed currents of different amplitudes on cathodic (Lithium Iron Phosphate, Lithium Manganese Dioxide) and anodic (Graphite and Li 4Ti5O12) half cells separately will impact the electrode materials in various ways. The results of charging time and effects on the electrode materials are compared with conventional charging method. Figures 1 and 2 show the constant current and a portion of pulsed current profile that are used in the analysis. In this experiment, pulsed current profile is controlled by varying the duty cycle and relaxation periods between pulses while the current amplitudes are reduced as the charging progress. SEM and equivalent circuit modelling based on EIS data are used in analyzing the impacts of both the charging protocols on the lithium-ion cells.