Sn restriction and Li2S reversible properties of novel sandwiched SnS@graphene hollow-sphere architecture for lithium storage.

Low reversion of Li 2 S and the Sn aggregation causing irreversible capacity loss are the primary cause of poor cycle performances in tin sulfide-based composites. These problems can be mitigated by confining SnS nanoparticles in sandwiched hollow-spherical graphene skeleton (Sandwich-SnS/GS), in which a large number of tiny SnS nanoparticles are inserted in between the interlayers of the sphere-like graphene shell with homogeneous distribution, while the spherical graphene interconnects each other forming a three-dimensional interconnected conductive network. This novel spherical graphene skeleton can immobilize the SnS and the lithiated products (Sn and Li 2 S) and suppress the local accumulation of metallic Sn at the largest extent, thus prompting the close contact of Sn/Li 2 S and their in-situ reverse transformation into SnS. In addition, the closed graphene sphere could inhibit the shuttle of lithium polysulfides derived from Li 2 S during charging, promote reversible transformation between Li 2 S and S 8 , providing an additional capacity contribution and ensuring the sustained capacity of the whole electrode without distinct decay. Thus, a high and stable reversible specific capacity of 756.7 mA h g−1 is retained in the Sandwich-SnS/GS composite after 200 cycles at 100 mA g−1, significantly higher than those of traditional hollow sphere and sandwich-like lamellar composite structures. [ABSTRACT FROM AUTHOR]