Correlation between irreversible capacity and electrolyte solvents degradation probed by NMR in Si-based negative electrode of Li-ion cell

•7Li & 19F MAS NMR is used to quantify electrolyte decomposition products•Carbon species are detected by 13C NMR•Main cause of irreversibility is the degradation of electrolyte solvent

Few studies relate that the failure mechanism of silicon-based electrodes is the SEI formation. In this work, we used quantitative solid-state high-resolution nuclear magnetic resonance to show that main cause of irreversible capacity is not the decomposition of lithium salt but the degradation of electrolyte solvent with the formation of non lithiated carbon species as polymer or oligomers.