Mo6+ Doping in Li3VO4 Anode for Li-Ion Batteries: Significantly Improve the Reversible Capacity and Rate Performance
Mo6+ Doping in Li3VO4 Anode for Li-Ion Batteries: Significantly Improve the Reversible Capacity and Rate Performance
复制标题
锂离子电池Li3VO4负极中Mo6掺杂：显着提高可逆容量和倍率性能
DOI：
10.1021/acsami.7b06459
复制
发表时间：
2017-08-23
影响因子：
9.5
通讯作者：
Zhao, Yanming
中科院分区：
文献类型：
--
作者：
Dong, Youzhong;Duan, He;Zhao, Yanming
考虑到纯Li 3VO 4的带隙为3.77 eV，几乎是绝缘体，为了显著提高其电导率，采用简单的溶胶-凝胶法成功制备了新型Li 3V 1-xMoxO 4（x = 0.00，0.01，0.02，0.05和0.10）正极材料。计算结果表明，用Mo ~（6+）取代V ~（5+）后，额外的电子占据了V ~（3 p）空轨道，使费米能级向导带移动，从而使Mo掺杂的Li_3VO_4成为导电体。V/I曲线测试表明，Mo掺杂使Li_3VO_4的电导率提高了5个数量级。极化明显减弱。交流阻抗测试结果表明，Mo掺杂可以获得更高的锂扩散系数。Mo掺杂Li 3VO 4的电子电导率显著提高，锂离子扩散系数增大，可逆容量和倍率性能明显改善。结果表明，Li 3V 1-xMoxO 4（x = 0.01）材料具有优良的倍率性能。在5C高倍率下，首次放电容量可达439 mAh/g，高于纯Li_3VO_4的166 mAh/g，100次循环后的平均容量衰减仅为0.06%。
Consider the almost insulator for pure Li3VO4 with a band gap of 3.77 eV, to significantly improve the electrical conductivity, the novel Li3V1-xMoxO4 (x = 0.00, 0.01, 0.02, 0.05, and 0.10) anode materials were prepared successfully by simple sol gel method. Our calculations show that, by substitute Mo6+ for V5+, the extra electron occupied the V 3p empty orbital and caused the Fermi level shift up into the conduction band, where the Mo-doped Li3VO4 presents electrical conductor. The V/I curve measurements show that, by Mo doping in V site, the electronic conductivity of the Li3VO4 was increased by 5 orders of magnitude. And thence the polarization was obviously reduced. EIS measurement results indicated that by Mo-doping a higher lithium diffusion coefficient can be obtained. The significantly increased electronic conductivity combined the higher lithium diffusion coefficient leads to an obvious improvement in reversible capacity and rate performance for the Mo-doped Li3VO4. The resulting Li3V1-xMoxO4 (x = 0.01) material exhibited the excellent rate capability. At a high rate 5 C, a big discharge capacity of the initial discharge capacity 439 mAh/g can be obtained, which is higher than that of pure Li3VO4 (only 166 mAh/g), and after 100 cycles the mean capacity fade is only 0.06% per cycle.