Li-rich oxide micro-bricks with exposed {010} planes to construct ultrahigh-compaction hierarchical cathodes for Li-ion batteries

Although lithium-rich manganese-based (LRM) cathode materials have high capacity (> ​250 ​mAh ​g−1) due to their multi-electron redox mechanisms and offer cost advantages due to their high Mn content, challenges remain before they can achieve commercialization as replacements for lithium cobalt oxides which have high volumetric energy density. Here, we construct a hierarchically structured LRM cathode, featuring primary micro-bricks and abundant exposure of lithium-ion active transport facets ({010} planes). Benefiting from these densely packed bricks and rapid lithium-ion active planes, the hierarchical material achieves an optimal compaction density of 3.4 ​g ​cm−3 and an ultrahigh volumetric energy density of 3431.0 ​Wh ​L−1, which is the highest performance level to date. Advanced characterizations, including hard X-ray absorption spectra and wide-angle X-ray scattering spectra, combined with density functional theory calculations, demonstrate that the hierarchical material shows a highly reversible charge compensation process and low-strain structural evolution. In addition, when the material has appropriate Li/Ni intermixing, it is not prone to shearing or sliding along the two-dimensional lithium-ion diffusion planes, which promotes robust architectural stability under high-pressure calendering and long-term cycling. This work should promote the development of advanced cathode materials for rechargeable batteries with high volumetric energy density.