Thermal and electrochemical characterization of MCMB/LiNi 1/3Co 1/3Mn 1/3O 2 using LiBoB as an electrolyte additive
The gas generation associated with the use of the lithium bis(oxalate)borate-(LiBoB) based electrolyte at the elevated temperature were detected in the pouch cell (MCMB/LiNi 1/3Co 1/3Mn 1/3O 2 with 10% excess Li), which might prevent the LiBoB usage as a salt. However, the cell capacity retention was improved significantly, from 87 to 96% at elevated temperature, when using LiBoB as an electrolyte additive. The capacity fade during cycling is discussed using d Q/d E, area specific impedance, and frequency response analysis results. Most of the capacity loss in the cell is associated with the rise in the cell impedance. Moreover, results from the differential scanning calorimetry indicate that the thermal stability of the negative electrode with the solid electrolyte interface (SEI) formed by the reduction of the LiBoB additive was greatly improved compared with that obtained from the reduction of LiPF 6-based electrolyte without additive. In this case, the onset temperature of the breakdown of the LiBoB-based SEI is 150 °C which is higher than that of the conventional electrolyte without additive. Furthermore, the total heat generated between 60 and 170 °C is reduced from 213 to 70 J g -1 when using LiBoB as electrolyte additive compared to the one without additive. In addition, the thermal stability of the charged LiNi 1/3Co 1/3Mn 1/3O 2 with 10% excess Li was not affected when using LiBoB as an electrolyte additive.