Extended Cycle Life Implications of Fast Charging for Lithium-Ion Battery Cathode

Tanvir R.Tanim, ZhenzhenYang, Andrew M. Colclasure, Parameswara R.Chinnam, Paul Gasper, Yulin Lin, Yu Lei, Peter J. Weddle, Jianguo Wen, Eric J. Dufek, Ira Bloom, Kandler Smith, Charles C.Dickerson, Michael C.Evans, Yifen Tsai, Alison R. Dunlop, Stephen E.Trask, Bryant J. Polzin, Andrew N. Jansen

July 2021 - Enabling extreme fast charging (XFC, ≤10–15 min charging) requires a comprehensive understanding of its implications. While lithium plating is a key bottleneck for the anode, the full extent of limitations for the cathode are not well-understood, particularly in extended-cycle settings with well-defined battery designs and conditions. This article presents cycle-life implications of XFC on cathodes at multiple length scales, combining electrochemical analyses, degradation modeling, and post-test characterizations. The comprehensive test matrix includes 41 well-defined gr/NMC pouch cells under varied fast-charge rates (1–9C) and state-of-charges cycled up to 1000 times. Cathode issues remain minimal in early cycling, but begin to accelerate in later life, when distinct cracking is found and identified as a fatigue mechanism. The bulk structure of cathodes remains intact, but distinct particle surface reconstruction is observed; however, this shows less pronounced effect on cathode aging than does cracking.

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