Analysis of cycling performance failure of NMC811/SiO-C pouch cells with high specific energy

NMC811/SiO-C cell is one of the most potential battery systems with high specific capacity, however, it is difficult to improve its poor cycling performance in practical application. To analysis the cycling failure mechanism of NMC811/SiO-C cell, electrode characterizations have been carried out by electrochemical impedance spectroscopy (EIS), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM),transmission electron microscope (TEM). The result showed that NMC811 cathode material can keep stable crystal structure and yield dissolving of metal ions during cycling, while SiO-C anode material suffered from structure cracking and displayed increasing consumption of electrolyte as well as growing SEI layer thickness. The changes in electrodes cause the serious specific capacity degradation and the poor cycling performance of NMC811/SiO-C pouch cells.