Nowadays, to adjust the fluctuations in electricity production and efficient use of midnight off-peaks for stable energy supply, the mid-large scale battery system has been growing up [1].  In particularly, sodium ion batteries have many interests as an alternative candidate for cost-advantage versus lithium ion batteries because of large amounts of reservation of sodium resources in earth. However, intrinsic structural disadvantage of interstitial tetrahedral sites dissimilar to the O3 structure led to the low discharge capacity and cycle retentions and it have not yet satisfactorily addressed. Recently, to breakthrough present drawbacks, we suggested the new concept of radially aligned hierarchical columnar structure with varied chemical composition.

To further study of novel nano-structured with varied chemical composition materials, we carry out the synthesis and characterization of O3-type layered structure cathode material of constant concentration Na[Ni_0.60Co_0.15Mn_0.25]O₂  and full concentration gradient Na[Ni_0.61Co_0.12Mn_0.27]O₂ material. Through the comparison of electrochemical properties and related structural properties, herein, we investigated and defined the novel concept FCG materials.

Especially, we focus on the effect of particle morphology and micro structured properties by using micro scope technique. We believe that the unexplored site of radially assembled nano-rod structure primary particles having varied chemical composition is highly contribute to high power and high energy Na-ion battery systems.

References

[1]         B. Scrosati, J. Hassoun, Y. K. Sun, Energy Environ. Sci. 2011, 4, 3287

[2]         J.-Y. Hwang, S.-M. Oh, S.-T. Myung, K.-Y. Chung, I. Belharouak, Y.-K. Sun. Nat. Commun. 6 (2015) 6865.