Novel Cathode Materials for Na-Ion Batteries Composed of Spoke-Like Nanorods of Na[Ni<sub>0.61sub>Co<sub>0.12sub>Mn<sub>0.27sub>]O<sub>2sub> Assembled in Spherical Secondary Particles
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- 作者：Jang-Yeon Hwang ; Seung-Taek Myung ; Chong Seung Yoon ; Sung-Soo Kim ; Doron Aurbach and Yang-Kook Sun
- 刊名：Advanced Functional Materials
- 出版年：2016
- 出版时间：November 22, 2016
- 年：2016
- 卷：26
- 期：44
- 页码：8083-8093
- 全文大小：3821K
- ISSN：1616-3028
文摘
The development of high-energy and high-power density sodium-ion batteries is a great challenge for modern electrochemistry. The main hurdle to wide acceptance of sodium-ion batteries lies in identifying and developing suitable new electrode materials. This study presents a composition-graded cathode with average composition Na[Ni<sub>0.61sub>Co<sub>0.12sub>Mn<sub>0.27sub>]O<sub>2sub>, which exhibits excellent performance and stability. In addition to the concentration gradients of the transition metal ions, the cathode is composed of spoke-like nanorods assembled into a spherical superstructure. Individual nanorod particles also possess strong crystallographic texture with respect to the center of the spherical particle. Such morphology allows the spoke-like nanorods to assemble into a compact structure that minimizes its porosity and maximizes its mechanical strength while facilitating Na<sup>+sup>-ion transport into the particle interior. Microcompression tests have explicitly verified the mechanical robustness of the composition-graded cathode and single particle electrochemical measurements have demonstrated the electrochemical stability during Na<sup>+sup>-ion insertion and extraction at high rates. These structural and morphological features contribute to the delivery of high discharge capacities of 160 mAh (g oxide)<sup>−1sup> at 15 mA g<sup>−1sup> (0.1 C rate) and 130 mAh g<sup>−1sup> at 1500 mA g<sup>−1sup> (10 C rate). The work is a pronounced step forward in the development of new Na ion insertion cathodes with a concentration gradient.