Carbon emission from non-renewable energy sources such as gasoline due to the drastically increasing energy demand becomes a critical issue in the world. This necessitates researchers to develop an environmental friendly energy storage that can meet the requirement for large devices particularly EVs. However, the current LIBs can’t provide sufficient energy density due to a limiting capacity of 372 mAh/g from graphite anode. Therefore, searching novel electrode materials for large energy storage that can deliver much higher capacity becomes very urgent. Sn has a 3 times greater capacity of ~1000 mAh/g that poses one of primary candidates for the next-generation LIBs. Sony released the first commercial amorphous Sn based battery called Nexelion that shows a 30% improved capacity than conventional graphite based battery in 2005. Scientists have made numerous attempts to stabilize the Sn alloy geometry by constructing nano-structures with carbon nanotubes, graphene, nanorods, nanocores, metal forms and metal alloy scaffold.

Here we present a novel Sn cage (Sn-NC) configuration comprising an industrially available, pure metal Sn and an oxide surface (not SnO_x). Through the in-situ TEM study on 3D Sn matrix, we found a well-designed space can accommodate the morphology change during the charging/discharging process (Liu, Nano Lett 2016). The protection of the rigid oxide surface and the adjustable interspace can prevent the pulverization and oxidation of the metal while supplying a fast Li⁺/e^- pathway. The coin/punch cells using Sn-NCs as anode provide a high capacity up to >600 mAh/g after ultra-long 5000 cycles at a high charge/discharge rate. The mass production of this anode material opens an avenue for industrial applications.