The dual role of zirconium in single-crystal Ni-rich cathodes as a promoter for grain growth and a pillar for structural stability for high-voltage lithium-ion batteries

초록

Single-crystalline, Ni-rich cathodes are promising candidates for next-generation lithium-ion batteries, offering enhanced mechanical stability over their polycrystalline counterparts. However, the high-temperature synthesis required for particle growth often leads to lithium loss and structural degradation. Herein, we present a dualfunctional doping strategy using zirconium (Zr) in a single-crystalline LiNi0.89Co0.05Mn0.05Al0.01O2 (SC-NCMA) material. As a grain growth promoter, Zr facilitates the formation of large, discrete single-crystal particles, which in turn enables a more uniform electrode microstructure. Simultaneously, as a structural pillar, the larger Zr4+ ions suppress Ni2+/Li+ cation mixing, stabilizing the layered framework and preserving facile lithium diffusion pathways. This synergistic design leads to a cathode with exceptional structural and interfacial stability. Consequently, the Zr-doped SC-NCMA cathode demonstrates remarkable high-voltage performance, retaining 88.1 % and 81.0 % of its initial capacity after 200 cycles in full-cells at 25 degrees C and 45 degrees C, respectively-significantly outperforming the pristine SC-NCMA. The enhanced stability was further evidenced by lower impedance growth and suppressed gas generation. This work provides a comprehensive strategy, from material design to electrode engineering, for advancing high-energy, long-lasting lithium-ion batteries.

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