A Wide Range of Testing Results on an Excellent Lithium-Ion Cell Chemistry to be used as Benchmarks for New Battery Technologies

TLDR

The study provides extensive benchmark data for a high‑performance lithium‑ion pouch cell to guide the development of advanced and beyond‑lithium‑ion chemistries. The authors performed up to three years of long‑term cycling, storage, and high‑precision coulometry at 20–55 °C on LiNi₀.₅Mn₀.₃Co₀.₂O₂/graphite pouch cells with various electrolytes, analyzing degradation mechanisms and impedance growth. The benchmark data are far superior to previous failure‑mechanism models, and the cells can drive an electric vehicle for over 1.6 million km and support more than two decades of grid‑storage use. The authors note that format‑dependent losses, such as between cylindrical and pouch cells, may not be reflected in the experiments.

Abstract

We present a wide range of testing results on an excellent moderate-energy-density lithium-ion pouch cell chemistry to serve as benchmarks for academics and companies developing advanced lithium-ion and other "beyond lithium-ion" cell chemistries to (hopefully) exceed. These results are far superior to those that have been used by researchers modelling cell failure mechanisms and as such, these results are more representative of modern Li-ion cells and should be adopted by modellers. Up to three years of testing has been completed for some of the tests. Tests include long-term charge-discharge cycling at 20, 40 and 55°C, long-term storage at 20, 40 and 55°C, and high precision coulometry at 40°C. Several different electrolytes are considered in this LiNi0.5Mn0.3Co0.2O2/graphite chemistry, including those that can promote fast charging. The reasons for cell performance degradation and impedance growth are examined using several methods. We conclude that cells of this type should be able to power an electric vehicle for over 1.6 million kilometers (1 million miles) and last at least two decades in grid energy storage. The authors acknowledge that other cell format-dependent loss, if any, (e.g. cylindrical vs. pouch) may not be captured in these experiments.