Bifunctional Co-B surface modification enhancing surface stability of single-crystalline ultra-high nickel ternary cathodes

Single-crystalline ultra-high nickel ternary cathodes have garnered significant attention as promising candidates for next-generation lithium-ion batteries due to their exceptional specific capacity and cost-effectiveness. However, severe interfacial side reactions during cycling, leading to rapid capacity decay, remain a major barrier to practical applications. In this work, we propose an innovative dual surface modification strategy that transforms residual lithium on the particle surface into LiCoO 2 and Li-B-O species. This bifunctional coating layer not only facilitates Li + diffusion but also suppresses parasitic side reactions and inhibits the formation of a detrimental rock-salt phase. The Co-B modified LiNi 0 . 94 Co 0 . 03 Mn 0 . 03 O 2 cathode delivers an impressive initial discharge capacity of 231.7 mAh·g −1 , while achieving 91.7 % capacity retention after 100 cycles at 1 C, significantly outperforming the 81.6 % retention of the pristine cathode. This work provides a novel strategy for enhancing the electrochemical stability of ultra-high nickel ternary cathodes. • Develop a dual surface modification method to reduce residual lithium. • Form capacity-contributing species that facilitate Li + diffusion. • Create a protective coating layer that inhibit electrolyte erosion.