Estimation of Induced Internal Pressure and Degradation in Small Prismatic Lithium-ion Cell

Lithium-ion Batteries (LiBs) tend to lose its capacity after every charge-discharge cycle. The loss in capacity depends primarily upon the operational temperature, Depth of Discharge (DoD), C-rate, and stacking pressure applied upon the cell surface. Although a significant amount of work has been accomplished to understand other parameters, the implication of stacking pressure and the effects of induced internal pressure is still much obscure. The present study incorporates an experimental setup to precisely estimate the capacity fade due to the increase in induced internal pressure inside a small prismatic LiB cell. To begin with, an initial pressure of 20kPa was externally applied on the cell surface and the ambient temperature was maintained at 25°C. The cell was then cycled at 100% DoD for 120 discrete cycles considering 0.5C charge and 1C discharge rates. Correspondingly, a correlation using the curve-fitting technique was formulated. Experimental data sets were then further extrapolated to apprehend the electrical and mechanical response towards the battery’s end of life. The proposed correlation estimates a life of 1154 cycles and an increase in internal pressure by 6.73 times until the cell degrades to 80% of its actual capacity.