NIBs have attracted significant interest during the last decade due to their cost-effectiveness compared to LIBs since sodium is the 6th most abundant element in the earth’s crust to a depth of 16 km.[1-3] Additionally, NIBs undergo reactions that are similar to those of LIBs in terms of ion intercalation and solid-state diffusion, phase transitions, surface film formation, and interfacial charge transfer processes, thereby facilitating the R&D process. 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[Ni0.61
, 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 nanorods 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.
 B. Scrosati, J. Hassoun, Y. K. Sun, Energy Environ. Sci. 2011, 4, 3287.
 V. Etacheri, R. Marom, R. Elazari, G. Salitra, D. Aurbach, Energy Environ. Sci. 2011, 4, 3243.
 J. Emsley, Nature’s Building Blocks, Oxford University Press, Oxford, UK 2011.