title: Reactive surface area of the Li(x)(Co(1/3)Ni(1/3)Mn(1/3))O2 electrode determined by μ(+)SR and electrochemical measurements.
abstract: The self-diffusion coefficient of Li(+) ions (D(Li)) in the positive electrode material Li(x)(Co(1/3)Ni(1/3)Mn(1/3))O2 has been estimated by muon-spin relaxation (μ(+)SR) using powder samples with x = 1-0.49, which were prepared by an electrochemical reaction in a Li-ion battery. Here, since the implanted muons sense a slight change in the internal magnetic field due to Li-diffusion, μ(+)SR provides an intrinsic D(Li) through the temperature dependence of the nuclear field fluctuation rate (ν) [Sugiyama et al., Phys. Rev. Lett., 2009, 103, 147601]. Both D(Li) at 300 K and activation energy (E(a)) were estimated to be ∼2.9 × 10(-12) cm(2) s(-1) and 0.074 eV for the x = 1 sample, ∼11.0 × 10(-12) cm(2) s(-1) and 0.097 eV for x = 0.70, and ∼8.9 × 10(-12) cm(2) s(-1) and 0.062 eV for x = 0.49, assuming that the diffusing Li(+) ions mainly jump from a regular occupied site to a regular vacant site. The estimated D(Li) was smaller by roughly one order of magnitude than those for Li(x)CoO2 in the whole x range measured. Furthermore, by making comparison with D(Li) obtained by electrochemical measurements, the reactive surface area of the Li(x)(Co(1/3)Ni(1/3)Mn(1/3))O2 electrode in a liquid electrolyte was found to strongly depend on x particularly at x > 0.8.
authors.affiliation: Toyota Central Research & Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan. e0589@mosk.tytlabs.co.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Sugiyama
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Mukai
authors.forename: Masashi
authors.initials: M
authors.lastname: Harada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nozaki
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Miwa
authors.forename: Taishi
authors.initials: T
authors.lastname: Shiotsuki
authors.forename: Yohei
authors.initials: Y
authors.lastname: Shindo
authors.forename: Sean R
authors.initials: SR
authors.lastname: Giblin
authors.forename: James S
authors.initials: JS
authors.lastname: Lord