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<p>The rapid development of new energy vehicles has driven the progress of lithium iron phosphate battery technology, but the energy density of lithium iron phosphate is relatively low. Lithium iron phosphate with high compaction density can significantly improve this problem, extend the driving range of electric vehicles, alleviate users’ range anxiety, and accelerate the replacement of fuel vehicles. In this paper, glucose, polyethylene glycol (PEG6000), tannic acid, and sophorolipid were used as composite carbon sources to obtain LiFePO<sub>4</sub>/C materials with high compaction density through the carbothermal reduction method. Sophorolipid, acting as a surfactant, enhanced the sphericity of primary particles during the grinding process and ensured a more uniform particle size distribution. In the spray drying phase, the formation of hydrogen bonds between tannic acid molecules promoted tighter binding of primary particles, thereby minimizing porosity. Owing to its elevated oxygen content, this conjugated organic substance resulted in reduced carbon content after sintering, thereby attaining an enhanced level of graphitic character. As the main carbon source, PEG6000 contributed to a decrease in carbon content within the coating layer. The resulting LiFePO<sub>4</sub>/C material exhibited a tap density of 2.62&#xa0;g&#xa0;cm<sup>−3</sup> when subjected to a pressure of 226&#xa0;MPa. Under discharge rates of 0.2C and 5C, the material delivered specific capacities of 166.3 and 145.4 mAh g<sup>−1</sup>, respectively. After undergoing 100 consecutive charge–discharge cycles at a 1C rate, the material demonstrated an impressive capacity retention of 99.04%. When fabricated into a 14500-type cylindrical battery, this material achieved a volumetric energy density of 1149.85 Wh L<sup>−1</sup> at 0.2C and 1094.18 Wh L<sup>−1</sup> at 1C. Compared with commercial lithium iron phosphate (with a compaction density of around 2.50&#xa0;g&#xa0;cm<sup>−3</sup>), the compaction density was increased by 4.8%.</p>

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Synthesis of high compaction density LiFePO4/C cathode material with compound carbon source based on tannic acid and sophorolipid

  • 期刊论文

  • 发表日期：

    2025年5月1日

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  • Hao Yang,
  • Yong Wang,
  • Xinran Li,
  • Quanchen Li,
  • Tianyi Zhang,
  • Zijun Liu,
  • Guangchuan Liang

摘要

The rapid development of new energy vehicles has driven the progress of lithium iron phosphate battery technology, but the energy density of lithium iron phosphate is relatively low. Lithium iron phosphate with high compaction density can significantly improve this problem, extend the driving range of electric vehicles, alleviate users’ range anxiety, and accelerate the replacement of fuel vehicles. In this paper, glucose, polyethylene glycol (PEG6000), tannic acid, and sophorolipid were used as composite carbon sources to obtain LiFePO4/C materials with high compaction density through the carbothermal reduction method. Sophorolipid, acting as a surfactant, enhanced the sphericity of primary particles during the grinding process and ensured a more uniform particle size distribution. In the spray drying phase, the formation of hydrogen bonds between tannic acid molecules promoted tighter binding of primary particles, thereby minimizing porosity. Owing to its elevated oxygen content, this conjugated organic substance resulted in reduced carbon content after sintering, thereby attaining an enhanced level of graphitic character. As the main carbon source, PEG6000 contributed to a decrease in carbon content within the coating layer. The resulting LiFePO4/C material exhibited a tap density of 2.62 g cm−3 when subjected to a pressure of 226 MPa. Under discharge rates of 0.2C and 5C, the material delivered specific capacities of 166.3 and 145.4 mAh g−1, respectively. After undergoing 100 consecutive charge–discharge cycles at a 1C rate, the material demonstrated an impressive capacity retention of 99.04%. When fabricated into a 14500-type cylindrical battery, this material achieved a volumetric energy density of 1149.85 Wh L−1 at 0.2C and 1094.18 Wh L−1 at 1C. Compared with commercial lithium iron phosphate (with a compaction density of around 2.50 g cm−3), the compaction density was increased by 4.8%.