Quantitative Nanoscale Mapping of Defects in Spinel Oxides for Multi-Valent Ion Batteries

Multivalent ion batteries are promising next-generation energy storage systems for grid-scale applications, due to their high volumetric capacity, low cost, good safety, and environmental friendliness. However, the insertion of multivalent ions in the cathode materials usually induces large lattice distortion, which impedes ion migration and impacts battery performance. In this work, a novel method is developed to introduce abundant defects into spinel oxide cathode materials to enhance their electrochemical performance. Through atomic resolution scanning transmission electron microscopy (STEM) imaging, four-dimensional STEM (4D-STEM), and electron energy loss spectroscopy (EELS), we demonstrate that the pre-engineered defects in the particles promote Zn-ion insertion and extraction. As a result, the cycling stability of Zn-ion batteries is significantly improved using the pre-engineered particles. Our work presents a novel defect introduction mechanism to promote multivalent ion diffusion in the abundant MnO₂ battery materials and provides guidance for defect-guided property engineering in ion-insertion materials.