School of Material Science and Technology , Jiangsu University , Zhenjiang 212013 , P. R. China.
ACS Appl Mater Interfaces. 2019 Oct 2;11(39):35777-35787. doi: 10.1021/acsami.9b12822. Epub 2019 Sep 17.
Cation-disordered oxide materials working as cathodes for Li-ion batteries have been at a standstill because of their structurally limited specific capacities (below 175 mAh g in most cases). In this work, we have introduced 4d Nb into host material LiNiTiO to synthesize Ni-based cation-disordered 3̅ Li-Ni-Ti-Nb-O compounds of LiNiTiNbO ( = 0, 5, 10, 15, 20) through a sol-gel method, showing particle sizes of less than 200 nm. Taking LiNiTiNbO with the best performance (an average voltage of ∼2.7 V and high discharge capacity of 221.5 mAh g) among oxides as a model, we study the relationship between the structure, morphology, redox mechanism, and electrochemical performance of cation-disordered oxides through a combination of X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption near-edge spectroscopy tests and in situ XRD with electrochemistry. The obtained results indicate that the improved capacity is mainly ascribed to Nb, which optimizes the Ni/Ni practical capacity and effectively stabilizes the O/O redox reaction. The results emphasize that Li-Ni-Ti-Nb-O compounds are promising members in the family of cation-disordered transition-metal oxide materials.
由于其结构上的比容量有限（大多数情况下低于 175 mAh g），作为锂离子电池正极的阳离子无序氧化物材料一直停滞不前。在这项工作中，我们通过溶胶-凝胶法将 4dNb 引入到主体材料 LiNiTiO 中，合成了 Ni 基阳离子无序 3̅Li-Ni-Ti-Nb-O 化合物 LiNiTiNbO（=0、5、10、15、20），粒径小于 200nm。以氧化物中性能最佳的 LiNiTiNbO（平均电压约为 2.7 V，放电容量高达 221.5 mAh g）为例，我们通过 X 射线衍射（XRD）、扫描电子显微镜、透射电子显微镜、X 射线光电子能谱和 X 射线吸收近边光谱测试以及电化学原位 XRD 相结合，研究了阳离子无序氧化物的结构、形貌、氧化还原机制和电化学性能之间的关系。结果表明，容量的提高主要归因于 Nb，它优化了 Ni/Ni 的实际容量，并有效地稳定了 O/O 氧化还原反应。结果强调了 Li-Ni-Ti-Nb-O 化合物是阳离子无序过渡金属氧化物材料家族中很有前途的成员。
