SnO2 is considered to be a promising candidate as anode material for lithium ion batteries,due to its high theoretical specific capacity(1494 mAh·g-1).Neverthe-less,SnO2-based anodes suffer from poor electronic con-ductivity and serious volume variation(300％)during lithiation/delithiation process,leading to fast capacity fading.To solve these problems,SnO2 quantum dots modified N-doped carbon spheres(SnO2 QDs@N-C)are fabricated by facile hydrolysis process of SnCl2,accom-panied with the polymerization of polypyrrole(PPy),fol-lowed by a calcination method.When used as anodes for lithium ion batteries,SnO2 QDs@N-C exhibits high dis-charge capacity,superior rate properties as well as good cyclability.The carbon matrix completely encapsulates the SnO2 quantum dots,preventing the aggregation and volume change during cycling.Furthermore,the high N content produces abundant defects in carbon matrix.It is worth noting that SnO2 QDs@N-C shows excellent capacitive contribution properties,which may be due to the ultra-small size of SnO2 and high conductivity of the car-bon matrix.