Additive Mass to Graphite Surface Area Ratio as Critical Parameter for Effective SEI Formation in Acetonitrile-Containing Electrolytes

Résumé fourni par la source

Acetonitrile (AN) has been proven as a Li ion battery (LIB) electrolyte solvent especially for low temperature applications. However, it is instability toward lithiated graphite and metallic Li creates multiple challenges to avoid electrolyte degradation. On one hand, the formation of a protective Solid Electrolyte Interphase (SEI), that is formed at a cell voltage, before AN is decomposed must be accomplished, and on the other hand, the deposition of metallic Li (plating) during formation and cycling must be avoided. This work shows that these goals are achievable in LiNi 0.8 Mn 0.1 Co 0.1 O 2 ||graphite cells by using sufficient amounts of vinylene carbonate (VC) and ethylene sulphite (ES) additives in an electrolyte with an AN content as high as 27.5%vol. While the purpose of ES is to ensure reduction of VC before AN, a high abundance of VC leads to a possibly differently composed, Li plating resistive SEI by promoting polymerisation reactions at the surface of the graphite anode. When the ratio of the VC mass and the graphite surface area (VC/GRSA) surpass a threshold of 59.06 mg m −2 , the formation process in cells with an areal (N/P) capacity ratio of 1.06 ± 0.02 is executed Li plating-free.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.