Improving the electrochemical properties of Cr-SnO2 by multi-protecting method using graphene and carbon-coating

Designing heteroatom doped metal oxides and modifying them with carbonaceous materials can grant metal oxides with good Li+ storage performance because of the improved structure stability and enhanced electric conductivity. Herein, monodispersed Cr-doped SnO2 quantum dots fixed by graphene nanosheets and carbon layers (C/Cr-SnO2/G) were successfully assembled, which showed excellent cyclic stability, high reversible capacity and remarkable rate capability for Li+ storage. According to the characteristics results, 3.8 wt% Cr were uniformly incorporated into SnO2 lattice in form of Cr3+, resulting the decrease of SnO2 diameters. The C/Cr-SnO2/G electrodes displayed an excellent reversible capacity of 672 mA h g(-1) after 200 cycles at 100 mA g(-1) without apparent capacity fading throughout the test, and still retained a stable specific capacity of 296 mA h g(-1) even at 5 A g(-1). The enhanced electrochemical performances of C/Cr-SnO2/G can be related to incorporation of Cr into lattice of SnO2 and the double structure protections by graphene nanosheets and carbon layers, which can easily obtain quantum dots structure, increase the conductivity, and keep the structure stability.