Modification Mechanisms and Synergistic Effects of Nb/Al Codoping in High‐Nickel Cathode Materials for Lithium‐Ion Batteries

Advanced medical imaging systems require exceptional reliability and extended service life. While high‐nickel layered cathode materials (Li[NixCoyMn1−x−y]O2, Ni ≥ 80%) offer high energy density, their structural instability threatens critical medical operations. This study addresses the challenges of electrochemical performance and structural stability in high‐nickel layered cathode materials. A codoping strategy using Nb5+ and Al3+ is employed to deeply explore the modification mechanisms and synergistic effects. The results indicate that Nb5+ doping induces a contraction of the primary particles, which enhances the crystal structure density and facilitates Li+ diffusion; however, it also increases Li+/Ni2+ cation mixing, potentially leading to irreversible capacity loss during the initial cycles. In contrast, the introduction of Al3+ effectively mitigates the cation mixing aggravated by Nb5+, maintaining the Li+/Ni2+ disorder within an optimal range. This adjustment significantly reduces electrode polarization during long‐term cycling and prevents the formation of microcracks. Consequently, the codoped cathode half‐cells retain 95.93% of their capacity after 200 cycles, while delivering a discharge capacity of 160.1 mAh g−1 at a 5 C rate. Moreover, both high‐temperature and room‐temperature performances are markedly improved. The synergistic effect of Nb5+ and Al3+ codoping not only stabilizes the layered structure but also enhances rate performance and cycle life.

Abstract licence: CC BY

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