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 ireversible 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 LixTMyBzO2 surface and a gradient-polyanions (BO33-/BO45-) doped interface, exceptionally boosting fast-charging and long-term cyclability. Our B-LRMO achieves a specific capacity of 305 mAh g-1 at 0.1 C, and retains 92% capacity after 200 cycles at 1 C, showing a voltage decay of only 0.788 mV per cycle. Even under extreme fast-charging rate of 5 C, B-LRMO maintains a capacity of 171 mAh g-1, and a 72% capacity retention after 600 cycles, outperforming pristine LRMO (39%) and most of reported LRMO works. Further, 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 Wh kg-1, and a 97% capacity retention after 30 cycles, demonstrative of enormous applicability. This work provides theoretical and experimental guideline for designing high-capacity and high-voltage LRMO cathodes towards fast-charging long-life LIBs.