Fast discharge process of layered cobalt oxides due to high Na⁺ diffusion.

ABSTRACT: Sodium ion secondary battery (SIB) is a low-cost and ubiquitous secondary battery for next-generation large-scale energy storage. The diffusion process of large Na(+) (ionic radius is 1.12 Å), however, is considered to be slower than that of small Li(+) (0.76 Å). This would be a serious disadvantage of SIB as compared with the Lithium ion secondary battery (LIB). By means of the electrochemical impedance spectroscopy (EIS), we determined the diffusion constant (D) of Na(+) in thin films of O3- and P2-type NaCoO2 with layered structures. We found that the D values (~ 0.5-1.5 × 10(-10) cm(2)/s) of Na(+) are higher than those (< 1 × 10(-11) cm(2)/s) of Li(+) in layered LiCoO2. Especially, the D values of O3-NaCoO2 are even higher than those of P2-NaCoO2, probably because O3-NaCoO2 shows succe

SUBMITTER: Shibata T 

PROVIDER: S-EPMC4355731 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature