UNDERSTANDING AND PREVENTING LIFETIME FAILURE IN LITHIUM-ION BATTERIES

Abstract

Researchers are rushing to improve the lifetime, energy density, and cost of lithium-ion batteries as their production grows to match increasing demand. They can achieve these goals by finding new electrolyte additives that increase long-term cycling performance or/and increase high voltage performance. They can also try to understand the mechanisms happening inside the cells to gain new knowledge that helps them in their quest. In this spirit, the first project consisted of studying a new family of electrolyte additives, the dioxazolone family. Dioxazolones with different functional groups were studied using long-term cycling, high-temperature storage, and other techniques to figure out if they would bring any advantage to the industry. Then, a second project was built to study a group of cells that cycled through different depth of discharge, C-rates, and temperature. Long-term cycling, dV/dQ analysis, thickness growth measurements, ultrasonic transmission mapping, X-ray CT scans, and other techniques were used to better understand the mechanisms that happen inside these cells. In the end, valuable knowledge was gained that would allow researchers to have a better intuition of the failure mechanisms happening inside cells.