Metal oxides hold the promise of high-capacity anodes for Li-ion batteries. Lithiation of binary metal oxides proceeds with two typical mechanisms: insertion and conversion. We characterize the two-step lithiation behavior of α-MoO3, namely, Li intercalation in the layered α-MoO3 leads to the formation of crystalline Li2MoO3 in the early stage of lithiation, and further Li insertion coverts LixMoO3 to metallic Mo and amorphous Li2O. The intercalation process is thermodynamically more favorable and is accompanied with a minor volumetric change, while the conversion reaction is kinetically slow and induces large deformation. Furthermore, instead of showing significant Li-embrittlement as seen in typical oxides, α-MoO3 remains defects free despite the nearly 100% repetitive volumetric change during lithiation cycles. The reaction mechanism, structural evolution, and mechanical behaviors are unveiled through coordinated in-situ transmission electron microcopy experiments on α-MoO3 nanobelts and first-principles computational studies. The results provide fundamental perspectives in the course of developing reliable high-capacity electrodes for Li-ion batteries.
Li, Y., Sun, H., Cheng, X., Zhang, Y., & Zhao, K. (2016). In-situ TEM experiments and first-principles studies on the electrochemical and mechanical behaviors of α-MoO3 in Li-ion batteries. Nano Energy, 27, 95–102. https://doi.org/10.1016/j.nanoen.2016.06.045