A Multi-Element Composition Modulation Strategy for Designing High-Capacity and Stable O3-Type Na-Layered Oxide.

Wang, Xubin; Yang, Wenfeng; Yang, Yang; Zhang, Jiao; Guo, Hao; Wang, Bowen; Lu, Yaxiang; Yu, Rong et al. · Adv Mater · 2025

basic_science · Level V

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Abstract

Unstable high-capacity cathodes remain a substantial barrier to enhancing the energy density of Na-ion batteries (NIBs). While the high-entropy strategy has demonstrated significant advantages in improving the performance of layered oxide cathodes, the specific capacities of reported high-entropy oxides remain relatively low (<150 mAh g<sup>-1</sup>). This prompts a reconsideration toward leveraging not just high entropy, but also the synergy among multiple elements to meet the demands for higher energy density. Herein, a multi-element composition modulation strategy is proposed to obtain cathodes without compromising on capacity, exemplified by LFANMT (NaLi<sub>0.05</sub>Fe<sub>0.04</sub>Al<sub>0.01</sub>Ni<sub>0.4</sub>Mn<sub>0.4</sub>Ti<sub>0.1</sub>O<sub>2</sub>), which achieves a remarkable specific capacity exceeding 180 mAh g<sup>-1</sup> at 4.3 V. It is visualized that single-crystal particles with surface compressive stress and bulk tensile stress exhibit superior surface lattice oxygen stability and crack resistance during cycling. Constructing an initial stress-protective layer is beneficial for alleviating the internal and external stress differences caused by uneven Na<sup>+</sup> extraction during the O3-P3 phase transition. Through precise elemental modulation, cathodes exhibiting excellent cycling stability with negligible voltage decay under high voltage are successfully obtained. The work provides an effective approach for designing high-capacity O3-type layered oxides for NIBs, emphasizing the importance of synergistic effects among elements.