Etching‐in‐a‐Box: A Novel Strategy to Synthesize Unique Yolk‐Shelled Fe₃O₄@Carbon with an Ultralong Cycling Life for Lithium Storage

An etching-in-a-box strategy is developed to synthesize unique Fe3O4@C yolk-shelled nanocubes. Interestingly, inner cavities are generated in Fe3O4 cores during the etching process. With an optimized etching time of 2 h, an ultralong cycling life is achieved, in which even after 8000 cycles the material can still deliver a significant capacity of 475 mAh g−1 at 10 A g−1. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.