Transition-Metal-Catalyzed Oxidation of Metallic Sn in NiO/SnO_2 Nanocomposite

摘要

It is well accepted that metallic tin as a discharge (reduction) product of SnO_x cannot be electrochemically oxidized below 3.00 V versus Li_+/Li_0 due to the high stability of Li_2O, though a similar oxidation can usually occur for a transition metal formed from the corresponding oxide. In this work, nanosized Ni_2SnO_4 and NiO/SnO_2 nanocomposite were synthesized by coprecipitation reactions and subsequent heat treatment. Owing to the catalytic effect of nanosized metallic nickel, metallic tin can be electrochemically oxidized to Sn02 below 3.00 V. As a result, the reversible lithium-storage capacities of the nanocomposite reach 970 mAhg~(-1) or above, much higher than the theoretical capacity (ca. 750 mAhg~(-1)) of SnO_2, NiO, or their composites. These findings extend the well-known electrochemical conversion reaction to non-transition-metal compounds and may have im-portant applications, for example, in constructing high-capacity electrode materials and efficient catalysts.