How Electrolytes Influence Battery Safety

TLDR

Conventional LiPF6‑based electrolytes generate flammable gases and high‑enthalpy combustion products, posing safety hazards that are often underestimated, and additive strategies to mitigate these risks have been limited by performance trade‑offs. The study aims to design new electrolyte additives that improve abuse tolerance while preserving cell performance. Additives are typically incorporated at sub‑10 % levels to avoid performance loss, which diminishes their effectiveness in reducing gas generation and flammability.

Abstract

Electrolytes have been shown to be a major source of poor safety response of Li ion cells. The physical hazards associated with conventional LiPF6 and carbonate-based electrolytes are well documented and include high volume gas decomposition products at elevated temperature, large combustion enthalpy and flammability of solvent vapor. However, the physical and health hazards of the decompositions products can be often overlooked. Electrolyte additives proposed to reduce gas generation and mitigate flammability have not gained much traction, in general, because of the trade-off in cell performance. To maintain cell performance, quantities of additives are generally introduced in fractions <10% which significantly decreases the efficacy of the additive. New additives need to be developed in order to strike the balance between improving abuse tolerance and maintaining performance.