Surface and structural stabilities of carbon additives in high voltage lithium ion batteries

The stabilities of different conductive carbon additives have been systematically investigated in high voltage lithium ion batteries. It is found that the higher surface area of conductive additives leads to more parasitic reactions initiating from different onset voltages. A closer inspection reveals that for the low surface area carbon such as Super P, PF6−PF6− anions reversibly intercalate into carbon structure at around 4.7 V. For high surface area carbons, in addition to the electrolyte decomposition, the oxidation of functional groups at high voltage further increases the irreversible capacity and Li+ ion consumption. Coulombic efficiency, irreversible capacity and cycling stability observed by using different carbon additives are correlated with their structure and surface chemistry, thus providing information for predictive selection of carbon additives in different energy storage systems.

► We investigate different carbon additives in high voltage lithium ion batteries.
► We examine the surface and structural stability of different carbons during charge to high voltage.
► Increasing surface area will increase irreversible capacity and reduce long-term cycling stability.
► Surface functional groups will be oxidized at high voltage and leads to poor cycling stability.