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Novel Cathode Materials for Na‐Ion Batteries Composed of Spoke‐Like Nanorods of Na[Ni 0.61 Co 0.12 Mn 0.27 ]O 2 Assembled in Spherical Secondary Particles
Author(s) -
Hwang JangYeon,
Myung SeungTaek,
Yoon Chong Seung,
Kim SungSoo,
Aurbach Doron,
Sun YangKook
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201603439
Subject(s) - nanorod , materials science , cathode , electrochemistry , ion , porosity , chemical engineering , particle (ecology) , nanotechnology , electrode , oxide , analytical chemistry (journal) , composite material , chemistry , metallurgy , chromatography , physics , quantum mechanics , oceanography , geology , engineering
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 0.61 Co 0.12 Mn 0.27 ]O 2 , 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 + ‐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 + ‐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) −1 at 15 mA g −1 (0.1 C rate) and 130 mAh g −1 at 1500 mA g −1 (10 C rate). The work is a pronounced step forward in the development of new Na ion insertion cathodes with a concentration gradient.