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<p>Amorphous materials, particularly lithium vanadophosphate glass, are a promising cathode for Mg-ion battery due to their potential to deliver higher specific capacity than crystalline counterparts. However, their intrinsically low electronic conductivity limits electrochemical performance. Herein, copper oxide (CuO) has been embedded in lithium vanadophosphate glass (4CuO – xV₂O₅ – (16–x) Li₂O – 80P₂O₅, where <i>x</i> = 4, 6, 8, and 10&#xa0;mol %) by a simple melt quenching method. The coexistence of mixed-valence vanadium ions and copper species establishes a synergistic mixed ionic–electronic conduction mechanism. Density and molar volume measurements indicated that increasing V₂O₅ enhanced network compactness and induced structural reorganization. The XRD patterns established the vitreous nature of all glass. FTIR measurements revealed the successful incorporation of V₂O₅ and CuO into the Li₂O–P₂O₅ network, accompanied by structural modifications and strengthened phosphate bonding. The presence of distinct transmittance bands corresponding to vanadium and copper ions confirmed the existence of three vanadium valences (V<sup>3+</sup>, V<sup>4+</sup>, V<sup>5+</sup>) and two copper valences (Cu<sup>+</sup>, Cu<sup>2+</sup>). The direct and indirect band gaps decreased with increasing V₂O₅ content, whereas Urbach energy was increased, attributed to intervalence charge transfer between Cu⁺/Cu²⁺ and V⁴⁺/V⁵⁺ centers. Impedance analysis shows that V₂O₅ doping significantly reduces resistance and activation energy, enhancing charge carrier density and mobility. AC conductivity followed Jonscher’s multipower law, with a transition in conduction mechanism from quantum mechanical tunneling in the base glass to correlated barrier hopping and overlapping large polaron tunneling in doped compositions. Electrochemical measurements demonstrate improved charge transfer, reversibility, and Mg²⁺ diffusion. The doped electrode delivers a higher discharge capacity (~ 140 mAh g⁻¹) than the undoped glass (~ 60 mAh g⁻¹) and exhibited more stable coulombic efficiency during cycling. These findings highlight vanadium-doped CuO–lithium phosphate glass as a promising cathode for multivalent-ion batteries.</p>

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Vanadium-doped CuO–lithium phosphate glass as high-capacity amorphous cathodes for magnesium-ion batteries

  • 期刊论文

  • 发表日期：

    2026年7月30日

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  • Norah Algethami,
  • Hind Albalawi,
  • Amal A. Altalhi,
  • Ashok Adhikari,
  • Fathy Salman,
  • E. Sheha,
  • Talaat A. Hameed

摘要

Amorphous materials, particularly lithium vanadophosphate glass, are a promising cathode for Mg-ion battery due to their potential to deliver higher specific capacity than crystalline counterparts. However, their intrinsically low electronic conductivity limits electrochemical performance. Herein, copper oxide (CuO) has been embedded in lithium vanadophosphate glass (4CuO – xV₂O₅ – (16–x) Li₂O – 80P₂O₅, where x = 4, 6, 8, and 10 mol %) by a simple melt quenching method. The coexistence of mixed-valence vanadium ions and copper species establishes a synergistic mixed ionic–electronic conduction mechanism. Density and molar volume measurements indicated that increasing V₂O₅ enhanced network compactness and induced structural reorganization. The XRD patterns established the vitreous nature of all glass. FTIR measurements revealed the successful incorporation of V₂O₅ and CuO into the Li₂O–P₂O₅ network, accompanied by structural modifications and strengthened phosphate bonding. The presence of distinct transmittance bands corresponding to vanadium and copper ions confirmed the existence of three vanadium valences (V3+, V4+, V5+) and two copper valences (Cu+, Cu2+). The direct and indirect band gaps decreased with increasing V₂O₅ content, whereas Urbach energy was increased, attributed to intervalence charge transfer between Cu⁺/Cu²⁺ and V⁴⁺/V⁵⁺ centers. Impedance analysis shows that V₂O₅ doping significantly reduces resistance and activation energy, enhancing charge carrier density and mobility. AC conductivity followed Jonscher’s multipower law, with a transition in conduction mechanism from quantum mechanical tunneling in the base glass to correlated barrier hopping and overlapping large polaron tunneling in doped compositions. Electrochemical measurements demonstrate improved charge transfer, reversibility, and Mg²⁺ diffusion. The doped electrode delivers a higher discharge capacity (~ 140 mAh g⁻¹) than the undoped glass (~ 60 mAh g⁻¹) and exhibited more stable coulombic efficiency during cycling. These findings highlight vanadium-doped CuO–lithium phosphate glass as a promising cathode for multivalent-ion batteries.