钠离子电池负极材料二氧化钛的氮离子掺杂改性研究

Nitrogen-Doped TiO_2 Nanofibers as Anode Materials for Sodium-Ion Batteries

二氧化钛(TiO_2)作为钠离子电池负极材料有着极大的应用前景,但是,低的电导率限制其大规模应用。通过静电纺丝的方法,制备出碳复合的锐钛矿二氧化钛(TiO_2)样品,并对样品进行氮掺杂,作为自支撑钠离子电池负极材料。通过XRD、SEM、XPS、充放电测试对其进行结构、形貌分析和电化学性能研究。结果发现,氮离子成功的掺入晶体内部,且对TiO_2的晶型没有影响。氮离子掺杂后,样品N-TiO_2的倍率性能有了明显的提高。在10 A·g^(-1)电流密度下,样品TiO_2和N-TiO_2的可逆比容量分别为134.3 m Ah·g^(-1)和212.1 m Ah·g^(-1)。在1 A·g^(-1)的电流密度下,样品N-TiO_2和TiO_2的可逆比容量分别为192.4 m Ah·g^(-1)、124.5 m Ah·g^(-1),循环1000圈后,放电比容量依然高达195.5 m Ah·g^(-1)、120.9 m Ah·g^(-1),样品N-TiO_2和TiO_2均具有优异的循环稳定性,但氮离子掺杂后,比容量有了显著的提高。实验表明,氮离子掺杂后,材料中产生的Ti^(3+)和氧空位可以提高电子电导率和Na^+在材料中的扩散效率,使得其电化学性能有了明显的改善。

Anatase TiO2 shows excellent long-term cycling stability as an anode for sodium-ion batteries. However, the low electrical conductivity limited its large-scale application. The carbon and anatase titanium dioxide nanoparticles （ TiOz ） complex was prepared by the method of electrospun, then combine nitrogen doping and prepared the samples of TiO：, N-TiO2, which as serf-standing anode materials for Na-ion battery. The effects of N3 - doping on the structure and electrochemical performance of the anatase TiO2 were studied by XRD, XPS, SEM and galvanostatic charge-dischargeand, respectively. The results show that the sample N-TiO2 has better ratio of performance than that of TiO2. Under l0 A·g^-1 current density, the reversible capacity of TiO2 and N-TiO2 were 134.3 mAh·g^-1 and 212.1 mAh·g^-1 Under the long-term cycles of 1 A·g^-1, the reversible capacity of N-TiO2 was 192.4 mAh ~ g-~ , and the discharge specific capacity was still as high as 195.5 mAh·g^-1 even after 1000 cycles, significantly higher than the discharge specific capacity of TiO2 samples. The results show that after the nitrogen doped, the formation of Ti^3＋ and oxygen vacancy effectively improve the electrical conductivity and the diffusion efficiency of Na ^＋ in material, so the electrochemical performance was improved obviously.