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<p>P2-type Fe/Cu/Mn layered oxides are promising cathode materials for sodium-ion batteries due to their high capacity and environmental benignity. However, under high-voltage conditions exceeding 4.2&#xa0;V, these materials are prone to undergo P2-O2 phase transformation and irreversible loss of lattice oxygen, leading to rapid capacity decay. To address these challenges, this work proposes a titanium-doping modification strategy, synthesizing a series of Ti-doped P2-type Na<sub>0.7</sub>Fe<sub>0.14</sub>Cu<sub>0.09</sub>Mn<sub>0.77-x</sub>Ti<sub>x</sub>O<sub>2</sub> (x = 0, 0.02, 0.05, 0.08) cathode materials, exploring the effect of Ti doping on the crystal structure and assessing the electrochemical performance of the materials. Results demonstrate that the incorporation of Ti into the transition metal layer stabilizes the layer structure, expends the Na layer spacing, and enhances Na<sup>+</sup> diffusion kinetics. The Na<sub>0.7</sub>Fe<sub>0.14</sub>Cu<sub>0.09</sub>Mn<sub>0.72</sub>Ti<sub>0.05</sub>O<sub>2</sub> (FCMT-5) electrode delivers a high initial discharge capacity of 164.36 mAh g<sup>−1</sup> in 1.5–4.5&#xa0;V, retains 78.89% after 100 cycles at 1 C, while the pristine one only yields 58.62% capacity retention. Besides, a high initial specific discharge capacity of 107.31 mAh g is retained at a high rate of 5C. Mechanistic analysis indicates that Ti doping not only suppresses the P2-O2 phase transition and lattice oxygen loss at high voltages but also reduces Mn<sup>3+</sup> content through charge compensation, alleviating Jahn–Teller distortion. This study provides a critical reference for the development of high-performance layered cathode materials for SIBs operating over a wide voltage range.</p>

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Effect of titanium doping on the structure and electrochemical performance of P2-Type Na₀.₇Fe₀.₁₄Cu₀.₀₉Mn₀.₇₇₋ₓTiₓO₂ cathode materials

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • Haichen Li,
  • Hu Fu,
  • Bolin Li,
  • Yuping Wu,
  • Zhirong Chen,
  • Qinran Zhang,
  • Hongming Zhou

摘要

P2-type Fe/Cu/Mn layered oxides are promising cathode materials for sodium-ion batteries due to their high capacity and environmental benignity. However, under high-voltage conditions exceeding 4.2 V, these materials are prone to undergo P2-O2 phase transformation and irreversible loss of lattice oxygen, leading to rapid capacity decay. To address these challenges, this work proposes a titanium-doping modification strategy, synthesizing a series of Ti-doped P2-type Na0.7Fe0.14Cu0.09Mn0.77-xTixO2 (x = 0, 0.02, 0.05, 0.08) cathode materials, exploring the effect of Ti doping on the crystal structure and assessing the electrochemical performance of the materials. Results demonstrate that the incorporation of Ti into the transition metal layer stabilizes the layer structure, expends the Na layer spacing, and enhances Na+ diffusion kinetics. The Na0.7Fe0.14Cu0.09Mn0.72Ti0.05O2 (FCMT-5) electrode delivers a high initial discharge capacity of 164.36 mAh g−1 in 1.5–4.5 V, retains 78.89% after 100 cycles at 1 C, while the pristine one only yields 58.62% capacity retention. Besides, a high initial specific discharge capacity of 107.31 mAh g is retained at a high rate of 5C. Mechanistic analysis indicates that Ti doping not only suppresses the P2-O2 phase transition and lattice oxygen loss at high voltages but also reduces Mn3+ content through charge compensation, alleviating Jahn–Teller distortion. This study provides a critical reference for the development of high-performance layered cathode materials for SIBs operating over a wide voltage range.