Effect of Co Incorporation of Ordered Mesoporous Sn-Based Alloy Materials for Li-Storage

Tuesday, October 13, 2015
West Hall 1 (Phoenix Convention Center)
J. Yoon (Department of Energy Science, Sungkyunkwan University), G. O. Park (Department of Energy Science, Sungkyunkwan University), S. B. Park (Department of Chemistry, Sungkyunkwan University), J. M. Kim (Department of Chemistry, Sungkyunkwan University), H. Kim (Hanyang University), and W. S. Yoon (Department of Energy Science, Sungkyunkwan University)
Sn-based intermetallic compound is general concept introducing second metal element to accommodate the inevitable internal strain caused by electrochemically induced volume change between tin and lithium-tin alloy during lithiation and delithiation processes. Particularly Co-Sn intermetallic compounds as an alternative anode material have been widely investigated during last decade due to the high capacity, cycle stability, and high rate performance. To the best of our knowledge, porous nanostructured intermetallic compound has not been investigated as anode for Li-ion battery because of the synthetic difficulty of controlling metal nucleation and sintering.
Ordered mesoporous CoSn intermetallic (CoxSny) with various Co/Sn ratio is successfully synthesized through nano-replication technique as stable and high power anode materials for lithium ion battery. Especially, this is the first result for the synthesis of ordered mesoporous CoSn intermetallic through the direct template method. The electrochemical results show that mesoporous CoxSny exhibits much better capacity than non-porous CoSn. Reversible capacity, coulombic efficiency, and cycle stability of mesoporous CoxSny materials are dependent on their structures and compositions. Especially, 30 atomic % Co contained ordered mesoporous Co0.3Sn0.7 shows 83% capacity retention after 50 cycle, which means Co atoms effectively accommodate the volume strain associates with the lithiation–delithiation processes. The rate performance of mesoporous Co0.3Sn0.7 is significantly improved, which was deeply related to the kinetic behavior such as low charge transfer resistance, large diffusion coefficient (small Warburg factor) and low internal resistance. Sustainable ordered pore structure even after 50 cycle was also observed with TEM, which means Co atoms play a buffer role effectively to accommodate the volume strain associated with the lithiation–delithiation processes.