Nanoparticles of SnO produced by sonochemistry as anode materials for rechargeable lithium batteries

Nanoparticles of SnO were synthesized sonochemically in mildly basic SnCl2 solutions. The amorphous product thus obtained could be transformed to a nanocrystalline phase by heating to 200 degreesC. Composite electrodes comprised (by weight) of 80% SnO, 10% graphite flakes (conductive additive), and 10% polymeric binder (an optimal composition) were tested as anodes for rechargeable Li batteries. The nanocrystalline SnO was found to be much more effective as an active material for electrodes than the initial amorphous phase. These electrodes could reach nearly their theoretical capacity (similar or equal to 790 mAh/g, SnO) in electrochemical lithiation-delithiation processes versus a Li counter electrode in nonaqueous Li salt solutions. However, there is still a long way to go to the possible use of SnO as an anode material in practical batteries. This is due to its high irreversible capacity (Li2O formation and surface film precipitation due to reactions of lithium-tin compounds with solution species) and gradual capacity decrease during repeated charge-discharge cycling. Possible reasons for this capacity fading are discussed. The tools for this study included electron microscopy (both TEM and SEM), thermal analysis (DSC), XRD, FTIR and impedance spectroscopies, and standard electrochemical techniques.