A surface-to-interface boronation engineering strategy stabilizing the O/Mn redox chemistry of lithium-rich manganese based oxides towards high energy-density cathodes

Abstract

Lithium-rich manganese-based oxides (LRMOs) are promising high-specific-energy cathode materials for lithium–ion batteries (LIBs) but face issues of voltage decay and poor cyclability rooted in the irreversible O/Mn redox. Herein, we present a general surface-to-interface boronation engineering strategy of stabilizing LRMO (B-LRMO) with an ion-conductive high-entropy Li_xTM_yB_zO₂ surface and a polyanion (BO₃³⁻/BO₄⁵⁻) gradient-doped interface, exceptionally boosting fast-charging and long-term cyclability. Our B-LRMO exhibits a specific capacity of 305 mA h g⁻¹ at 0.1C, and retains 92% capacity after 200 cycles at 1C, showing a voltage decay of only 0.788 mV per cycle. Even at an extreme fast-charging rate of 5C, B-LRMO maintains a capacity of 171 mA h g⁻¹, and a 72% capacity retention after 600 cycles, outperforming pristine LRMO (39%) and most of the reported LRMOs. Furthermore, we evidence that boronation engineering effectively strengthens the reversibility of O/Mn redox chemistry, leading to improved structural reversibility, enhanced cationic/anionic redox kinetics, reduced metal/oxygen loss, and boosted Li⁺ storage performance. Our 4.99 Ah pouch cells (B-LRMO‖graphite) deliver an energy density of 329 W h kg⁻¹, and a 97% capacity retention after 30 cycles, demonstrative of enormous applicability. This work provides theoretical and experimental guidelines for designing high-capacity and high-voltage LRMO cathodes towards fast-charging long-life LIBs.