@article{oai:tsukuba.repo.nii.ac.jp:00036395,
 author = {小林, 航 and 守友, 浩 and Yanagita, Ayumu and Shibata, Takayuki and Kobayashi, Wataru and Moritomo, Yutaka},
 issue = {10},
 journal = {APL Materials},
 month = {Oct},
 note = {Layered cobalt oxide, P2-Na x CoO2, is a prototypical cathode material for sodium-ion secondary battery. We systematically investigated the rate dependence of the discharge capacity (Q) in three thin films of Na 0.68CoO2 with different film thickness (d) and in-plane grain radius (r). With subtracting conventional voltage drop effect on Q, we derived an intrinsic rate dependence of Q. We found a scaling relation between the renormalized discharge rate (γ ≡ r 2/DT; D and T are the Na + diffusion constant and discharge time, respectively) and relative capacity (=Q/Q 0; Q 0 is the value at a low rate limit). The observed scaling relation is interpreted in terms of the Na + intercalation process at the electrolyte-Na x CoO2 interface and Na + diffusion process within Na x CoO2.},
 title = {Scaling relation between renormalized discharge rate and capacity in Na x CoO2 films},
 volume = {3},
 year = {2015}
}