Highly Ordered SnO2 Nanopillar Array as Binder-Free Anodes for Long-Life and High-Rate Li-Ion Batteries.

SnO2, a typical transition metal oxide, is a promising conversion-type electrode material with an ultrahigh theoretical specific capacity of 1494 mAh g-1. Nevertheless, the electrochemical performance of SnO2 electrode is limited by large volumetric changes (~300%) during the charge/discharge process, leading to rapid capacity decay, poor cyclic performance, and inferior rate capability. In order to overcome these bottlenecks, we develop highly ordered SnO2 nanopillar array as binder-free anodes for LIBs, which are realized by anodic aluminum oxide-assisted pulsed laser deposition. The as-synthesized SnO2 nanopillar exhibit an ultrahigh initial specific capacity of 1082 mAh g-1 and maintain a high specific capacity of 524/313 mAh g-1 after 1100/6500 cycles, outperforming SnO2 thin film-based anodes and other reported binder-free SnO2 anodes. Moreover, SnO2 nanopillar demonstrate excellent rate performance under high current density of 64 C (1 C = 782 mA g-1), delivering a specific capacity of 278 mAh g-1, which can be restored to 670 mAh g-1 after high-rate cycling. The superior electrochemical performance of SnO2 nanoarray can be attributed to the unique architecture of SnO2, where highly ordered SnO2 nanopillar array provided adequate room for volumetric expansion and ensured structural integrity during the lithiation/delithiation process. The current study presents an effective approach to mitigate the inferior cyclic performance of SnO2-based electrodes, offering a realistic prospect for its applications as next-generation energy storage devices.