Nano-(V1/2Sb1/2Sn)O4: A high capacity, high rate anode material for Li-ion batteries

Abstract

Vanadium antimony tin oxide, M (micron size)-(V1/2Sb 1/2Sn)O4 with tetragonal rutile structure is prepared for the first time. The N (nanosize, 10-20 nm)-analogue is obtained by high energy ball milling of the above. They are characterized by Rietveld refinement of the X-ray diffraction data, high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), density and BET surface area studies. The Li-cycling properties were studied at ambient temperature (24 °C) and at 54 °C by galvanostatic discharge-charge cycling and cyclic voltammetry. Nano-(V1/2Sb1/2Sn)O4 shows stable cycling performance at 24 °C with capacities 450, 435 and 360 (±5) mA h g-1 at rates of 0.43, 1.0 and 3.5 C, respectively, in the range, 0.005-1.0 V vs. Li. These values are stable up to 100 cycles at 0.43 C and up to at least 50 cycles at 1 C and 3.5 C. At 54 °C and at 0.43 C, N-(V 1/2Sb1/2Sn)O4 delivers a stable capacity of 440 (±5) mA h g-1 in the range, 5-100 cycles. Under similar conditions the cycling performance of M-(V1/2Sb1/2Sn) O4 is inferior to that of the N-analogue. The M- and N-(V 1/2Sb1/2Sn)O4 showed main cathodic and anodic peaks at ∼0.2 V and ∼0.5 V, respectively, by CV. Complementary impedance studies are reported at various voltages and as a function of cycle number to support the Li-cycling mechanism involving alloying-de-alloying reactions of Sn and Sb with Li using (VO) as an inert matrix. © 2010 The Royal Society of Chemistry.