Application of the 'confusion principle' to Sn-based materials as negative electrode materials for Li-ion batteries

The 'confusion principle' (Greer. Nature, 366, 303 (1993)) is applied to tin-3d transition metals carbon alloys to obtain a nanostructured negative electrode material. Various Sn-TMs-C samples with TMs = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu (all included with same atomic ratios) were prepared by mechanical milling and by mechanical alloying. Each 10-component alloy sample was examined structurally using X-ray diffraction (XRD) and electrochemically using Li/Sn-TM-C cells. The sample Sn₁₀TMs₈₀C₁₀ showed a nanostructured or amorphous-type XRD pattern, which shows the validity of this principle. XRD patterns of samples prepared with higher Sn atomic content showed crystalline features of Sn-based intermetallics. As expected, a very low specific capacity ( ≪ 100 mAh/g) was observed for the sample Sn₁₀TMs₈₀C₁₀. The sample Sn₃₀TMs₃₀C₄₀ had the highest specific capacity (near 400 mAh/g) of the samples prepared. However, features of Sn aggregation were noticed at cycle number 80 of the latter sample, which are normally detrimental to the capacity retention upon further cycling. (author)