A Systematic Study of Electrolyte Additives in Single Crystal and Bimodal LiNi<sub>0.8</sub>Mn<sub>0.1</sub> Co<sub>0.1</sub>O<sub>2</sub>/Graphite Pouch Cells
Wentao Song, Jessie Harlow, E. R. Logan, Helena Hebecker, Matt Coon, Laurent Molino, Michel B. Johnson, J. R. Dahn, Michael Metzger
Abstract
A few weight percent of electrolyte additives can dramatically improve Li-ion battery performance and lifetime. A systematic investigation of a series of electrolyte additive formulations was performed on bimodal (BM) and single crystal (SC) LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811)/artificial graphite (AG) pouch cells. Long-term cycling tests at different temperatures (20 °C, 40 °C, and 55 °C) and different upper cutoff voltages (4.06 V and 4.20 V) were performed. These tests results were combined with advanced characterization techniques like ultra-high precision charging (UHPC), ex-situ gas measurement, and automatic cell storage tests to rank the additives based on their effectiveness. Radar plots and a figure-of-merit (FOM) approach were further utilized to summarize results for the BM and SC NMC811/AG cells. This work provides a useful benchmark for those developing NMC811/graphite cells and gives important insights for future electrolyte additive studies.