Unraveling SEI formation and cycling behavior of commercial Ni-rich NMC Li-ion pouch cells through operando optical characterization

Lithium-ion batteries, relying on Ni-rich NMC (LiNixMnyCo1_x_yO2) phases, are widely used in various applications due to their high energy density and extended cycle life. However, further improvements are possible with a deeper understanding of their internal chemistry in real-world conditions. Here, using optical fiber Bragg grating sensors placed inside commercial pouch cells, we demonstrate the feasibility of monitoring the heat release during the formation cycles and real-driving cycling. By collecting temperature data for Li-ion cells using different types of NMCs, we were able to extract the contribution of the anode and the impact of additives on overall heat generation. We also present a comparison of the heat generation of NMC-based batteries under varying power and voltage levels, which provides insights into battery safety in dynamic, real-world environments. Our study reveals the importance of continuously monitoring batteries heat release throughout its lifespan to enhance our understanding of the interconnected materials surfaces and electrolyte reactions.

Automated summary

In this study, temperature data were collected using optical fiber Bragg grating sensors placed inside commercial pouch cells, allowing for monitoring the heat release during the formation cycles and real-driving cycling. The research provides insights into the contribution of the anode and the impact of additives on overall heat generation, as well as a comparison of the heat generation of NMC-based batteries under varying power and voltage levels. Continuous monitoring of battery heat release throughout its lifespan enhances our understanding of interconnected materials surfaces and electrolyte reactions.