The effect of electrolyte additives upon the lithium kinetics of Li-Ion cells containing MCMB and LiNiᵪCo₁-ᵪO2 electrodes and exposed to high temperatures

Abstract

With the intent of improving the performance of lithium-ion cells at high temperatures, we have investigated the use of a number of electrolyte additives in experimental MCMB- LiᵪNiᵧCo₁-ᵧO₂ cells, which were exposed to temperatures as high as 80°C. In the present work, we have evaluated the use of a number of additives, namely vinylene carbonate (VC), dimethyl acetamide (DMAc), and mono-fluoroethylene carbonate (FEC), in an electrolyte solution anticipated to perform well at warm temperature (i.e., 1.0M LiPF₆ in EC+EMC (50:50 v/v %). In addition, we have explored the use of novel electrolyte additives, namely lithium oxalate and lithium tetraborate. In addition to determining the capacity and power losses at various temperatures sustained as a result of high temperature cycling (cycling performed at 60° and 80°C), the three-electrode MCMB-LiᵪNiᵧCo₁-ᵧO2 cells (lithium reference) enabled us to study the impact of high temperature storage upon the solid electrolyte interphase (SEI) film characteristics on carbon anodes (MCMB-based materials), metal oxide cathodes, and the subsequent impact upon electrode kinetics.