Numerical optimization of lithium-ion cell performance using metaheuristic algorithms

The specific energy and power are key performance characteristics of lithium-ion cells. The active materials of these cells determine the energy storage capacity and control their energy and power. The inactive components, on the other hand, influence the electrical losses, the active material utilization uniformity and the heat dissipation. They also contribute significantly to the cell weight. These components must therefore be properly designed in order to optimize the cells performance and weight. The present paper focuses on the optimization of the design of the inactive components. It concentrates on lithium-ion NMC pouch cells and considers three objectives: maximize the specific energy; maximize the specific power, and a trade-off between the two. The optimization combines three metaheuristics with the simulation tool Battery Design Studio to identify the best combination. Evaluations showed that the Cuckoo search algorithm offers the best response. An analysis of the results led to the following conclusions: (i) Large numbers of electrode pairs are beneficial; (ii) Counter-located tabs provide better performance, but lead to bigger cells than the co-located tab option. Thus, the counter-located tab configuration represents the right design for an optimal specific power, whereas co-located tabs are more appropriate for the specific energy; (iii) Finally, the average aspect ratio (height/width) established considering all optimized configurations is less than 0.47. This indicates that the aspect ratios of commercial cells, which are generally greater than 1.0, are not optimal.