Probing the Causes and Effects of Parasitic Reactions in Lithium-Ion Cells

Abstract

Parasitic reactions in lithium-ion cells consume solvent, salt and active lithium ions, resulting in a loss of capacity and eventual cell failure. The projects described in this thesis have the common goal of exposing the chemical mechanisms of these parasitic reactions and probing their effects on cell performance. Three types of projects are described in this thesis. The first part of this thesis is focused on exposing and probing the effects of parasitic reactions that cause the evolution and consumption of gases in lithium-ion cells. The second project is focused on probing how the conditions of the first cycle of a lithium-ion cell impact the amount of parasitic reactions in subsequent cycles. The third project describes the development and use of a new analytical tool for quantifying the solvent/salt ratio in the electrolyte of aged cells. This work improves the understanding of certain parasitic reactions that may contribute to capacity fade and eventual failure of lithium-ion cells.