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<p>Lithium iron phosphate (LiFePO<sub>4</sub>) exhibits intrinsically low electronic conductivity, while carbon nanotubes (CNTs) tend to aggregate in aqueous systems, leading to discontinuous conductive networks. Here, a synergistic noncovalent dispersion strategy based on tannic acid (TA) and polyvinylpyrrolidone (PVP) is proposed to improve the stability of CNTs dispersion and enhance their performance in LiFePO<sub>4</sub> cathodes. Conductive slurries with different TA/PVP mass ratios were prepared and systematically characterized by Raman spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM), and further evaluated electrochemically in LiFePO<sub>4</sub> half-cells. Optimal dispersion is achieved at 15 wt.% TA and 25 wt.% PVP, where CNTs bundles are effectively exfoliated. Under these conditions, the <i>I</i><sub><i>G</i></sub><i>/I</i><sub><i>D</i></sub> ratio increases to 0.984, the average particle size decreases to 471.04&#xa0;nm, and the slurry resistivity is reduced to 0.0402 Ω·cm. This improvement is attributed to the formation of a continuous and percolated three-dimensional conductive network, the electrode delivers a high discharge capacity of 146.26 mAh g<sup>− 1</sup> at a current density of 0.1&#xa0;C. At 1&#xa0;C, the capacity is enhanced by 33.2% compared with the PVP-only system, and excellent capacity retention of 99.13% is achieved after 100 cycles. The synergistic effect of TA and PVP effectively mitigates electrode polarization and reduces charge-transfer impedance, providing a useful reference for the development of high-performance conductive slurries for aqueous lithium-ion batteries.</p>

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Synergistic non-covalent dispersion of carbon nanotubes using tannic acid/PVP for enhanced conductive networks in LiFePO4 cathodes

  • 期刊论文

  • 发表日期：

    2026年5月20日

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  • Han Zhang,
  • Zehui Gong,
  • Wenlong Zheng,
  • Hailong Chen

摘要

Lithium iron phosphate (LiFePO4) exhibits intrinsically low electronic conductivity, while carbon nanotubes (CNTs) tend to aggregate in aqueous systems, leading to discontinuous conductive networks. Here, a synergistic noncovalent dispersion strategy based on tannic acid (TA) and polyvinylpyrrolidone (PVP) is proposed to improve the stability of CNTs dispersion and enhance their performance in LiFePO4 cathodes. Conductive slurries with different TA/PVP mass ratios were prepared and systematically characterized by Raman spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM), and further evaluated electrochemically in LiFePO4 half-cells. Optimal dispersion is achieved at 15 wt.% TA and 25 wt.% PVP, where CNTs bundles are effectively exfoliated. Under these conditions, the IG/ID ratio increases to 0.984, the average particle size decreases to 471.04 nm, and the slurry resistivity is reduced to 0.0402 Ω·cm. This improvement is attributed to the formation of a continuous and percolated three-dimensional conductive network, the electrode delivers a high discharge capacity of 146.26 mAh g− 1 at a current density of 0.1 C. At 1 C, the capacity is enhanced by 33.2% compared with the PVP-only system, and excellent capacity retention of 99.13% is achieved after 100 cycles. The synergistic effect of TA and PVP effectively mitigates electrode polarization and reduces charge-transfer impedance, providing a useful reference for the development of high-performance conductive slurries for aqueous lithium-ion batteries.