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<p>Aqueous sodium-ion batteries (ASIBs) are promising for large-scale energy storage due to their cycling stability, safety, and environmental friendliness. However, ​structural instability of cathode materials limits cycle life, while the narrow electrochemical window constrains energy density. In this work, tunnel-type Cu-doped Na<sub>0.44</sub>MnO<sub>2</sub> was synthesized via a high-temperature solid-state method. Cu doping suppresses Jahn–Teller (J-T) distortion by reducing the formation of J-T active Mn<sup>3+</sup> and strengthening Mn–O bonds, ​thereby enhancing structural stability and extending cycle life​. Simultaneously, Cu doping expands Na⁺ diffusion channels, mitigating irreversible strain and suppressing voltage decay​ during cycling. Na<sub>0.44</sub>Mn<sub>0.95</sub>Cu<sub>0.05</sub>O<sub>2</sub> exhibits ​outstanding long-term cycling stability (99.5–100% capacity retention after 2000 cycles at 5 C) and ​superior rate capability. The Na⁺ diffusion coefficient reaches 7.04 × 10<sup>−12</sup> cm<sup>2</sup>&#xa0;s<sup>−1</sup>, nearly an order of magnitude higher than that of undoped Na<sub>0.44</sub>MnO<sub>2</sub> (8.89 × 10<sup>−13</sup> cm<sup>2</sup>&#xa0;s<sup>−1</sup>). The mechanisms of Cu doping in stabilizing lattice dynamics and ion transport are systematically discussed.</p>

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The electrochemical performance of Cu2+-doped Na0.44MnO2 cathode material for aqueous sodium-ion battery

  • 期刊论文

  • 发表日期：

    2025年9月17日

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  • Jintao Ma,
  • Weiqi Li,
  • Huan He,
  • Donglou Ren,
  • Tianquan Liang

摘要

Aqueous sodium-ion batteries (ASIBs) are promising for large-scale energy storage due to their cycling stability, safety, and environmental friendliness. However, ​structural instability of cathode materials limits cycle life, while the narrow electrochemical window constrains energy density. In this work, tunnel-type Cu-doped Na0.44MnO2 was synthesized via a high-temperature solid-state method. Cu doping suppresses Jahn–Teller (J-T) distortion by reducing the formation of J-T active Mn3+ and strengthening Mn–O bonds, ​thereby enhancing structural stability and extending cycle life​. Simultaneously, Cu doping expands Na⁺ diffusion channels, mitigating irreversible strain and suppressing voltage decay​ during cycling. Na0.44Mn0.95Cu0.05O2 exhibits ​outstanding long-term cycling stability (99.5–100% capacity retention after 2000 cycles at 5 C) and ​superior rate capability. The Na⁺ diffusion coefficient reaches 7.04 × 10−12 cm2 s−1, nearly an order of magnitude higher than that of undoped Na0.44MnO2 (8.89 × 10−13 cm2 s−1). The mechanisms of Cu doping in stabilizing lattice dynamics and ion transport are systematically discussed.