Lithium Battery Electrolyte Additives Suppress Gas Generation

The patent introduces a specific electrolyte additive comprising a cyclic carboxylate compound and a chain carboxylate compound as intermediaries to mediate between the carbonate solvent and the carbon negative electrode. These additives form a modified SEI film that prevents direct harmful reactions while maintaining ion conductivity. The cyclic carboxylate (first additive) and chain carboxylate (second additive) work together to create a stable interface layer that blocks gas-generating side reactions.

The patent changes the chemical composition parameters of the electrolyte by adding specific carboxylate compounds with controlled concentrations (cyclic carboxylate: 0.01-5 wt%, chain carboxylate: 0.01-5 wt%). This parameter modification alters the SEI film formation process, transforming it from a gas-generating reaction to a controlled film-forming process that maintains conductivity while preventing harmful gas evolution.

The patent applies preliminary action by forming a stable, protective SEI film during initial charging that pre-prevents high-temperature degradation. The electrolyte additives create a robust SEI film structure during formation that resists disintegration at high temperatures, thereby preventing subsequent gas generation and capacity loss during storage. This preliminary protective layer eliminates the need for continuous repair reactions that occur in conventional batteries.

The patent uses a composite approach by combining two different carboxylate compounds (cyclic and chain types) in the electrolyte. This composite additive system creates a synergistic effect where the cyclic carboxylate provides structural stability and the chain carboxylate enhances flexibility and coverage, together forming an SEI film with superior high-temperature stability that prevents disintegration and maintains capacity retention.