Deciphering the functionalization routes for SnO2 anodes

In this report, investigations on pristine vs. hybrid SnO2 modified by four different routes are reported. The pristine SnO2 is a potential anode with high theoretical capacity (1494 mAhg−1), but the volumetric issues prevails the viability of this material in Li-ion battery systems. For enhancing the stability and anode specific properties, SnO2 is incorporated with CNT, ZnO, Li, and amorphous/less crystalline phase of its own. Both physical and electrochemical aspects of the SnO2 experience huge improvement on changing its pristine nature. Structural analysis made by XRD indicates that except SnO2/ZnO matrix, all the samples are phase pure falling into the tetragonal symmetry. SnO2/ZnO sample possesses mixed tetragonal and hexagonal symmetry. The presence of foreign elements greatly impacts the morphological patterns of the sample as ensured by TEM analysis. Doping helps in bandgap engineering of the pristine material by decreasing the energy gap value and thereby improving the redox properties of pristine. Cyclic voltammetry analysis shows betterment in the electrochemical properties of the SnO2 material, whereas galvanostatic charge–discharge analysis shows specific capacitances, 158 mAhg−1, 450 mAhg−1, ~ 225 mAhg−1, 425 mAhg−1, 275 mAhg−1 with respect to SnO2, SnO2/CNT, SnO2/ZnO, SnO2/Li, and composite SnO2 for 1000 cycles with a Coulombic efficiency of ~ 99% except SnO2/Li. Overall, the order of anodic performance of the materials is sorted as, SnO2/CNT, SnO2/Li, SnO2/ZnO, composite SnO2, and pristine SnO2. In summary, the investigations on SnO2 hybrids have shown promising results in improving their properties, especially in capacitance and life time. Inspired by this, future investigations related to SnO2 hybrids will likely revolve around optimizing their anodic properties by improving their long-term stability and compatibility with different battery materials.