摘要
Na_(3)V_(2)(PO_(4))_(3)(NVP)电池材料较低的本征电子电导率导致其在电化学反应过程中倍率性能较差且容量衰减显著。为此,本研究采用在NVP的V位引入五种微量金属离子的高熵掺杂策略,设计了一种高性能的钠离子电池正极材料Na_(3)V_(1.9)(MnCrCaMgAl)_(0.02)(PO_(4))_(3)/C(HE-NVP/C)复合材料,并采用改进的溶胶凝胶燃烧法合成。通过X射线衍射仪、比表面积及孔隙分析仪、扫描电子显微镜和透射电子显微镜对材料结构进行表征,并采用电池测试系统和电化学工作站对其电化学性能进行测试。结果表明,所合成HE-NVP/C复合材料由具有介孔结构且表面均匀包覆非晶态碳层的微米级块状颗粒组成。高熵微掺杂未改变NVP的晶格类型,HE-NVP/C复合材料中的NVP仍为六方晶系,且由于五种掺杂元素的协同作用,晶胞体积几乎不变。高熵微掺杂可以显著增加NVP/C电极材料的多孔结构,从而缩短钠离子的传输路径,增大电极材料的比表面积,为电化学反应提供更多的活性位点,进而提高储钠性能。HE-NVP/C样品的电化学可逆性、电子电导率和钠离子扩散速率均比NVP/C样品高,且具有优异的倍率性能和循环性能。倍率从0.2 C升至10 C时,HE-NVP/C样品的平均放电比容量从113.08 mA·h/g降至103.60 mA·h/g;倍率回到0.2 C时,容量恢复至112.02 mA·h/g。在1 C倍率下,HE-NVP/C首次放电比容量为108.16 mA·h/g,经100次循环后容量保持率为93.39%。在10 C倍率下,HE-NVP/C首次放电比容量为102.16 mA·h/g,经500次循环后容量保持率为70.58%。
The low intrinsic electronic conductivity of Na_(3)V_(2)(PO_(4))_(3)(NVP)leads to poor rate performance and significant capacity decay during electrochemical reactions.Therefore,in this study a high-entropy doping strategy is adopted by introducing five trace metal ions into the V-site of NVP to design a high-performance sodium-ion battery cathode material,Na_(3)V_(1.9)(MnCrCaMgAl)_(0.02)(PO_(4))_(3)/C(HE-NVP/C)composite,which was synthesized using an improved sol-gel combustion method.The structure of the material was characterized by X-ray diffractometer,specific surface area and porosity analyzer,scanning electron microscope and transmission electron microscope,and its electrochemical performance was evaluated by battery test system and electrochemical workstation.The results show that the synthesized HE-NVP/C composite is composed of micron-sized blocky particles with mesoporous structure and uniform coating of amorphous carbon layer.High-entropy micro-doping preserves the rhombohedral lattice structure of NVP,and the unit cell volume is almost unchanged due to the synergistic effect of five doping elements.High-entropy micro-doping can significantly increase the porous structure of the NVP/C electrode material,thereby shortening the transport path of sodium ions,increasing the specific surface area of the electrode material,and providing more electrochemical active sites,which collectively improve the sodium storage performance.The electrochemical reversibility,electronic conductivity and sodium-ion diffusion rate of HE-NVP/C sample are higher than those of NVP/C.Consequently,HE-NVP/C exhibits excellent rate capability and cycling performance.As the rate increases from 0.2 C to 10 C,the average discharge specific capacity of the HE-NVP/C sample decreases from 113.08 mA·h/g to 103.60 mA·h/g.When the rate is returned to 0.2 C,the capacity recovers 112.02 mA·h/g.At a rate of 1 C,the initial discharge specific capacity of the HE-NVP/C sample is 108.16 mA·h/g and the capacity retention rate is 93.39%after 100 cycles.At a rate of 10 C,the HE-NVP/C sample exhibits an initial discharge specific capacity of 102.16 mA·h/g and maintains a capacity retention of 70.58% after 500 cycles.
作者
李娜丽
郑立明
LI Na-li;ZHENG Li-ming(College of Vanadium and Titanium,Panzhihua University,Panzhihua 617000,China;Vanadium and Titanium Critical Strategic Materials Key Laboratory of Sichuan Province,Panzhihua University,Panzhihua 617000,China)
出处
《稀有金属与硬质合金》
北大核心
2025年第6期152-162,共11页
Rare Metals and Cemented Carbides
基金
四川省钒钛材料工程技术研究中心开放项目(2023FTGC12,2024FTGC05)
攀枝花学院校级培育类科研项目(2023PY04)
省级大学生创新创业训练计划项目(S202411360021)。
关键词
磷酸钒钠
钠离子电池
溶胶凝胶燃烧
高熵微掺杂
非晶态碳层
储钠性能
微观结构
Na_(3)V_(2)(PO_(4))_(3)
sodium ion battery
sol-gel combustion
high-entropy micro-doping
amorphous carbon layer
sodium storage performance
microstructure
