MultiscaleDefect Regulation of Cobalt-Free LayeredOxides for High-Energy and Long-Lasting Cathodes

Reducing the reliance on cobalt in electrode chemistry is a promising step toward more sustainable and cost-effective lithium-ion batteries. However, the elimination of cobalt in layered oxides generally results in a significant decrease in capacity and/or a compromised cycle stability. Herein, we show that these intertwined issues of the cobaltless systems can be remedied by meticulously tailoring inherent defects induced at multiscale. It is demonstrated that a simple excess incorporation of lithium in the structure can effectively reduce the cation disorder and unexpectedly alter the microstructure forming routes, thereby enhancing electro-chemo-mechanical stabilities of layered cathodes. Our investigations reveal that this surplus lithium facilitates topotactic lithiation of precursors during calcination, rendering mechanically robust particles with fewer nanoporous defects and reduced cation disorder. Defect-regulated cobalt-free layered oxides successfully deliver a reversible capacity of 189 mAh g^–1 at 0.5C with a retention of ∼85% after 300 cycles under commercial-level electrode loading.