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<p>Lithium substitution is a promising strategy to enhance the electrochemical properties of P2-type layered manganese-based cathodes for sodium-ion batteries (SIBs). However, the influence of lithium (Li) substitution content on the structure-property relationship remains a subject of debate. To clarify this, a series of Li-substituted P2-Na<sub>0.7</sub>MnO<sub>2</sub> (NMO-L-x), were systematically investigated via a combination of Rietveld XRD, XPS, HRTEM, and electrochemical analysis. It is found that at low substituting levels (x ≤ 0.07), Li⁺ predominantly occupy transition metal (TM) sites, leading to an expansion of the O–Na–O interlayer spacing and an increased average Mn oxidation state. With increased substitution (0.07 &lt; x ≤ 0.14), Li⁺ co-occupies both TM and Na layers. Further doping (x ≥ 0.21) induces the formation of an electrochemically inactive Li<sub>2</sub>MnO<sub>3</sub> secondary phase alongside the P2 structure. As a cathode for SIBs, the optimized phase-pure sample NMO-L-0.07 delivers a high reversible capacity of 144.5&#xa0;mAh&#xa0;g<sup>−1</sup> at 0.2 C and exhibits superior rate capability, retaining 85.6&#xa0;mAh&#xa0;g<sup>−1</sup> at 10 C. This enhanced performance is attributed to the Li-induced expansion of the O–Na–O interlayer spacing and the effective suppression of Jahn–Teller distortion through the stabilization of the host structure. This work systematically elucidates the influence of Li substitution content on the structural evolution and electrochemical performance of P2-Na<sub>0.7</sub>MnO<sub>2</sub>, demonstrating that controlled Li doping is an effective approach for optimizing high-performance P2-type Mn-based cathodes for SIBs.</p>

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The influence of lithium substitution on the structural evolution and electrochemical performance of P2-Na0.7MnO2

  • 期刊论文

  • 发表日期：

    2026年4月29日

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  • Shumin Sun,
  • Yongqin Zhai,
  • Gencheng Deng,
  • Tangen Liang,
  • Peiyuan Wang,
  • Shaoming Fang

摘要

Lithium substitution is a promising strategy to enhance the electrochemical properties of P2-type layered manganese-based cathodes for sodium-ion batteries (SIBs). However, the influence of lithium (Li) substitution content on the structure-property relationship remains a subject of debate. To clarify this, a series of Li-substituted P2-Na0.7MnO2 (NMO-L-x), were systematically investigated via a combination of Rietveld XRD, XPS, HRTEM, and electrochemical analysis. It is found that at low substituting levels (x ≤ 0.07), Li⁺ predominantly occupy transition metal (TM) sites, leading to an expansion of the O–Na–O interlayer spacing and an increased average Mn oxidation state. With increased substitution (0.07 < x ≤ 0.14), Li⁺ co-occupies both TM and Na layers. Further doping (x ≥ 0.21) induces the formation of an electrochemically inactive Li2MnO3 secondary phase alongside the P2 structure. As a cathode for SIBs, the optimized phase-pure sample NMO-L-0.07 delivers a high reversible capacity of 144.5 mAh g−1 at 0.2 C and exhibits superior rate capability, retaining 85.6 mAh g−1 at 10 C. This enhanced performance is attributed to the Li-induced expansion of the O–Na–O interlayer spacing and the effective suppression of Jahn–Teller distortion through the stabilization of the host structure. This work systematically elucidates the influence of Li substitution content on the structural evolution and electrochemical performance of P2-Na0.7MnO2, demonstrating that controlled Li doping is an effective approach for optimizing high-performance P2-type Mn-based cathodes for SIBs.