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Lessons Learned from Long-Term Cycling Experiments with Pouch Cells with Li-Rich and Mn-Rich Positive Electrode Materials

2022; Institute of Physics; Volume: 169; Issue: 6 Linguagem: Inglês

10.1149/1945-7111/ac76e8

1945-7111

R. Väli, Stuart Aftanas, Ahmed Eldesoky, Aaron Liu, Tina Taskovic, Jessie Harlow, Jack deGooyer, Nutthaphon Phattharasupakun, Dongxu Ouyang, Divya Rathore, Marc M. E. Cormier, Michel B. Johnson, HongNam Nguyen, HunHo Kwak, Shinichi Kumakura, Jens Paulsen, J. R. Dahn,

Advanced Battery Technologies Research

In this work, the performance of commercial (250–300 mAh) Li 1.11 Ni 0.34 Mn 0.53 Al 0.02 O 2 /graphite (LNMA) and Li 1.167 Ni 0.183 Mn 0.558 Co 0.092 O 2 /graphite (LNMC) pouch cells was evaluated using different cycling drive profiles, temperatures, formation voltages, cycling upper and lower cut-off voltages. A variety of electrolyte additives and additive combinations were tested in the LNMA cells. The best performing electrolyte in high voltage LNMA cells (4.6 V upper cut-off) was Control + 2% fluoroethylene carbonate (FEC) + 1% lithium difluorophosphate (LFO) + 1% lithium difluoro(oxalato)borate (LiDFOB) with 87% capacity retention after 720 cycles. LNMA cells cycled to 4.25 V and LNMC cells cycled to 4.44 V at 40 °C were able to cycle for 1000 cycles before reaching 80% capacity. These materials can have surprisingly good high-voltage performance, but we stress that a fundamental breakthrough that can eliminate the voltage fade that is ubiquitous in Li-rich and Mn-rich materials is necessary to make Li-rich materials competitive with existing cell chemistries. We demonstrate that the high specific capacity of Li-rich materials can be deceptive when making conclusions about the energy density of Li-rich/graphite full cells. Hopefully, these results can set a baseline for other researchers in the Li-rich space.