Junjie Niu1 Shuai Kang1 Xi Chen1

1, Univ of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States

Scientists have made numerous attempts to stabilize the Sn alloy geometry by constructing nano-structures with carbon nanotubes, graphene, nanorods and metal alloy scaffold. However, most of these Sn particles can’t long survive due to severe agglomerations, leading to a limited cyclic capability. A rapid capacity decay and a low rate performance are usually detected, posing an urgent need in preventing pulverization and contact loss upon a long cycling. Here by making a wide-size-ranging hybrid composite of Sn kernel and TiO2 skin, with a tunable interspace, we have achieved a long life of >10000 cycles at fast rates of 5.0 C and 10.0 C charge/discharge rate with reversible capacity exceeding 662 (double times of graphite) and 360 mAh/g, respectively (Nano Letters, 2018, in print, DOI: 10.1021/acs.nanolett.7b04416). At 1.0 C, the capacity exceeds 727 mAh/g with a Coulombic efficiency of >99.8% after 3000 cycles. Our ‘Skin Grafting’ route is simple and industrially scalable. The long cycling and fast charge/discharge performance makes this battery a high potential in replacing graphite based lithium-ion batteries (LIBs) for practical applications in electric vehicles (EVs).