Crack-induced abrupt capacity degradation in commercial LiNi0.8Co0.1Mn0.1O2 (NCM811)/SiOx-graphite pouch batteries

Reasons for abrupt capacity fading in commercial LiNi0.8Co0.1Mn0.1O2 (NCM811)/SiOx-graphite pouch batteries were evaluated using electrochemical methods. These approaches consist of charge and discharge curves, differential curves and electrochemical impedance spectroscopy (EIS), and some advanced verification techniques constituting scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The predominance testament concerning capacity attenuation through experimental verification after the battery is disassembled proves that the silicon-based anode material deteriorates further, bringing about a significant number of cracks with the progression of cycles. In addition, electrolyte enters into the cracks, generating the excessive growth of the solid electrolyte interface (SEI) and the expansion of impedance, which eventually causes the failure of conductive networks, dilemma of ion transmission and increment in polarization, ultimately contributing to lithium dendrites.