Comparative study of bulk and nano-structured mesoporous SnO₂ electrodes on the electrochemical performances for next generation Li rechargeable batteries

For next generation Li-ion batteries, advanced electrode materials with high energy densities are mightily important issue. Since the partial oxidation of Sn with Li₂O to form SnO_x was demonstrated upon delithiation in SnO₂ anode, the additional conversion reaction has contributed that the theoretical capacity of SnO₂ can be extended from 783 to 1494 mAh g⁻¹. Herein, with the design of additional conversion reaction, we discuss key factors for high electrochemical performances of the SnO₂ anodes through comparative analysis between nano-structured mesoporous SnO₂ and conventional bulk SnO₂, based on synchrotron radiation-based techniques, quantitative analysis of extended X-ray absorption fine structure spectra, and bond strength calculation. In this way, we demonstrate that the mesoporous SnO₂ has a nano-engineered structure with the weakened Sn-O bond strength for inducing the enhanced reversible conversion reaction as well as the facilitated electrochemical reaction, and a void structure for relieving the severe volume changes during lithiation/delithiation. Consequently, excellent electrochemical performance through the additional reversible conversion reaction is obtained in the mesoporous SnO₂. Insight from this research enables important advance in the development of metal oxide-based anode materials by making irreversible reaction reversible, providing a realizable strategy for the design and creation of high-energy storage devices.