Na4Mn3(PO4)2P2O7 (NMPP) cathode materials exhibit promising application potential in sodium-ion batteries (SIBs), leveraging its cost-competitive advantages and high theoretical energy density. However, its low conductivity and Jahn–Teller effect induced by Mn3+ ions result in rapid capacity fading and lattice distortion, severely limiting its practical application in SIBs. In this study, we propose a synergistic optimization strategy combining cobalt doping with dual-carbon coating to enhance the electrochemical performance of the cathode material. Systematic investigations demonstrate that Co2+ substitution effectively regulates the electronic structure, enhancing redox activity in the high-voltage region (> 4.1 V) while suppressing Jahn–Teller lattice distortion of Mn3+, thereby accelerating Na+ diffusion kinetics and improving cycling stability. Furthermore, the dual-carbon microsphere structure formed by rGO and amorphous carbon composite coating establishes an efficient conductive network, enhancing the structural stability and conductivity. The optimized NMC1.0PP@rGO delivers a high initial discharge capacity of 116.43 mA h g−1 at 0.1C and demonstrates superior cycling stability with 80.7% capacity retention after 200 cycles at 5C, along with Coulombic efficiency exceeding 99%. This work provides a rational strategy to enhance the electrochemical performance of NMPP, highlighting its promising application prospects for manganese-based mixed phosphate materials. Graphical abstract A synergistic optimization strategy of cobalt doping and dual-carbon coating is applied to enhance the electrochemical performance of the Na4Mn3(PO4)2P2O7 cathode material. Appropriate cobalt substitution effectively alleviates Jahn–Teller distortion, improves the phase purity, and increases the redox activity in the high-voltage region. Meanwhile, a dual-carbon-coated microsphere architecture formed by rGO and amorphous carbon establishes an efficient conductive network. The optimized NMC1.0PP@rGO cathode demonstrates a high reversible capacity of 116.43 mAh g−1 at 0.1C and superior cycling stability with 80.7% capacity retention after 200 cycles at 5C.

Synergistic cobalt doping and dual-carbon coating Na₄Mn₃(PO₄)₂P₂O₇ microspheres as high-performance cathode for sodium-ion batteries

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发表日期：

2025年9月27日

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Zekai Wei,
Anyu Hu,
Feiyu Lu,
Guoxing Wei,
Yanpeng Fu,
Ye Xiao,
Zhicong Shi

摘要

Na₄Mn₃(PO₄)₂P₂O₇ (NMPP) cathode materials exhibit promising application potential in sodium-ion batteries (SIBs), leveraging its cost-competitive advantages and high theoretical energy density. However, its low conductivity and Jahn–Teller effect induced by Mn³⁺ ions result in rapid capacity fading and lattice distortion, severely limiting its practical application in SIBs. In this study, we propose a synergistic optimization strategy combining cobalt doping with dual-carbon coating to enhance the electrochemical performance of the cathode material. Systematic investigations demonstrate that Co²⁺ substitution effectively regulates the electronic structure, enhancing redox activity in the high-voltage region (> 4.1 V) while suppressing Jahn–Teller lattice distortion of Mn³⁺, thereby accelerating Na⁺ diffusion kinetics and improving cycling stability. Furthermore, the dual-carbon microsphere structure formed by rGO and amorphous carbon composite coating establishes an efficient conductive network, enhancing the structural stability and conductivity. The optimized NMC_1.0PP@rGO delivers a high initial discharge capacity of 116.43 mA h g⁻¹ at 0.1C and demonstrates superior cycling stability with 80.7% capacity retention after 200 cycles at 5C, along with Coulombic efficiency exceeding 99%. This work provides a rational strategy to enhance the electrochemical performance of NMPP, highlighting its promising application prospects for manganese-based mixed phosphate materials.

Graphical abstract

A synergistic optimization strategy of cobalt doping and dual-carbon coating is applied to enhance the electrochemical performance of the Na₄Mn₃(PO₄)₂P₂O₇ cathode material. Appropriate cobalt substitution effectively alleviates Jahn–Teller distortion, improves the phase purity, and increases the redox activity in the high-voltage region. Meanwhile, a dual-carbon-coated microsphere architecture formed by rGO and amorphous carbon establishes an efficient conductive network. The optimized NMC_1.0PP@rGO cathode demonstrates a high reversible capacity of 116.43 mAh g⁻¹ at 0.1C and superior cycling stability with 80.7% capacity retention after 200 cycles at 5C.

Synergistic cobalt doping and dual-carbon coating Na4Mn3(PO4)2P2O7 microspheres as high-performance cathode for sodium-ion batteries

摘要

Synergistic cobalt doping and dual-carbon coating Na₄Mn₃(PO₄)₂P₂O₇ microspheres as high-performance cathode for sodium-ion batteries