Interfacial storage of lithium in the nanostructure of SnO2 nanobaskets for capacities exceeding theoretical values

SnO2 nanobasket electrodes sputtered onto templated copper substrates exhibit extremely high capacities, approximately 1480 mAh/g, compared to the theoretical capacity based on alloying, 781 mAh/g. This anomalous capacity is investigated via galvanostatic cycling and sample sintering. We determined that the capacity, which exceeds the theoretical value for this range, was due to interfacial charging of lithium at the phase boundaries of nanoparticles in the SnO2 electrode. This phenomenon, which can only be observed in nanostructured electrodes of high interfacial surface area/volume ratios, shows great promise in fabrication of extremely high-capacity electrodes for lithium batteries.