Electrochemical activity of carbon blacks in LiPF6-based organic electrolytes

Electrochemical behavior of carbon black (CB) additives in 1 M LiPF6 EC/DEC (3:7 vol.) electrolyte in the operation potential range of positive electrodes in Li-ion cells was investigated. Various carbon blacks display noticeable electrochemical activity towards PF6a intercalation and electrolyte oxidation at potentials >4.0 V vs. Li/Li+. In situ X-ray diffraction, Raman spectroscopy, and ex situ scanning electron microscopy and Fourier Transform Infrared (FTIR) spectroscopy showed that repetitive intercalation/deintercalation of PF6a anions leads to structural alteration and degradation of carbon black nanoparticles. The mechanism of these interfacial processes on CB electrodes and their implications for electrochemical performance of high-voltage Li-ion electrodes during long-term cycling is evaluated.