Operando NMR and XRD study of chemically synthesized LiC oxidation in a dry room environment

We test the stability of pre-lithiated graphite anodes for Li-ion batteries in a dry room battery processing room. The reaction between LiCx and laboratory air was followed using operando NMR and x-ray diffraction, as these methods are sensitive to change in Li stoichiometry in graphite. There is minimal reactivity between LiC6 and N2, CO2 or O2; however, LiC6 reacts with moisture to form lithium (hydr)oxide. The reaction rate follows zero-order kinetics with respects to intercalated lithium suggesting that lithium transport through the graphite is fast. The reaction occurs by sequential formation of higher stages–LiC12, then LiC18, and then LiC24–as the hydrolysis proceeds to the formation of LixOHy and graphite end products. Slowing down the formation rate of the LixOHy passivation layer stabilizes of the higher stages.