A Direct Comparison of Pilot-Scale Li-Ion Cells in the Formats PHEV1, Pouch, and 21700

Li-ion cells of the industrially-relevant formats PHEV1 (prismatic), multi-layer pouch, and 21700 (cylindrical) are directly compared by experiments for the first time. All three cell formats were reproducibly built on pilot-scale with the same anode (graphite), cathode (NMC622), separator, and electrolyte allowing a direct comparison. The main differences between these formats are their capacities (24.6 Ah, 2.2 Ah, 2.3 Ah), volume/surface ratios, as well as tab and the jellyroll/stack configurations (flat-wound, stacked, wound). The comparison involves voltage curves during formation (0.1 C), discharge rate capability (0.5 C-3 C), heating behaviour, cell impedances, geometrical properties such as electrode curvatures and tab configurations, as well as comparison with coin half cells with anode and cathode vs Li counter electrode. The data are put into context with commercial and pilot-line built cells from other studies.

Automated summary

In this study, Li-ion cells of industrially-relevant formats, including PHEV1 (prismatic), multi-layer pouch, and 21700 (cylindrical), were directly compared for the first time. Despite using the same materials and configurations, these cell formats showed differences in capacities, volume/surface ratios, and configurations, with various parameters such as formation processes, discharge rate capabilities, and geometrical properties being compared to provide insights into their performance. The data were also compared with cells from other studies to provide a comprehensive analysis.