Composite cathodes have attracted great attention due to the integrated advantages of each
pure structure. Also, the component ratio deserves a careful modulation to further improve
the corresponding electrochemical performance. Mn-based layer–tunnel hybrid composite
became a focus in sodium-ion batteries due to the superiority in terms of high performance,
low cost, and nontoxicity. In the previous reports, the structure modulation was carried out
via changing the synthesis condition, varying the transition-metal-element ratio, and different …