Ultra-fine porous SnO2 nanopowder prepared via a molten salt process: a highly efficient anode material for lithium-ion batteries

Ultra-fine porous SnO2 nanoparticles for lithium ion batteries were prepared by a simple, easily scaled-up molten salt method at 300 degrees C. The structure and morphology were confirmed by X-ray diffraction and transmission electron microscopy. The as-prepared SnO2 had a tetragonal rutile structure with crystal sizes around 5 nm. The electrochemical performance was tested compared with commercial nanopowder and previously reported nanowires. The as-prepared nanoparticles delivered a significantly higher discharge capacity and better cycle retention. The nanoparticle electrode delivered a reversible capacity of 410 mAh g(-1) after 100 cycles. Even at high rates, the electrode operated at a good fraction of its capacity. The excellent electrochemical performance of the ultra-fine porous SnO2 can be attributed to the ultra-fine crystallites (which tend to decrease the absolute volume changes) and the porous structure (which promotes liquid electrolyte diffusion into the bulk materials and acts as a buffer zone to absorb the volume changes).