Fast-charging of Lithium Iron Phosphate battery with ohmic-drop compensation method: Ageing study

One of the major issues hampering the acceptance of electric vehicles (EVs) is the anxiety associated with
long charging time. Hence, the ability to fast charging lithium-ion battery (LIB) systems is gaining notable
interest. However, fast charging is not tolerated by all LIB chemistries because it affects battery functionality
and accelerates its aging processes. Here, we investigate the long-term effects of multistage fast
charging on a commercial high power LiFePO4-based cell and compare it to another cell tested under
standard charging. Coupling incremental capacity (IC) and IC peak area analysis together with mechanistic
model simulations (‘Alawa’ toolbox with harvested half-cell data), we quantify the degradation
modes that cause aging of the tested cells. The results show that the proposed fast charging technique
caused similar aging effects as standard charging. The degradation is caused by a linear loss of lithium
inventory, coupled with a less degree of linear loss of active material on the negative electrode. This
study validates fast charging as a feasible mean of operation for this particular LIB chemistry and cell
architecture. It also illustrates the benefits of a mechanistic approach to understand cell degradation on
commercial cells.