title: Simple size control of TiO2 nanoparticles and their electrochemical performance: emphasizing the contribution of the surface area to lithium storage at high-rates.
abstract: The particle size effects of TiO2 nanoparticles (TNPs), which are composed of small crystallites, on Li ion storage are a very fundamental and important subject. However, size control of TNPs under 200 nm using a sol-gel method has been limited due to the highly reactive precursor, titanium alkoxide. In this study, TNPs with various sizes even under 100 nm are obtained by controlling the reactant concentrations in a mixed solvent of ethanol and acetonitrile. Among them, three different sizes of TNPs are prepared to compare the Li ion storage capacity, and 60 nm TNPs are found to have the best reversible capacity of 182 mA h g(-1) after 50 cycles at 1 C and a remarkable rate performance of 120 mA h g(-1) at 10 C. Capacity increase upon cycling is observed in the size-controlled TNPs, and the explanation of this phenomenon is proposed to the lattice volume expansion of TiO2 upon intercalation for enabling further penetration of the electrolyte into the particles' interior. Moreover, the capacity at high rates is more closely related to the surface area from Hg porosimetry analysis than from typical N2 adsorption/desorption analysis.
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 151-747, Korea. jinklee@snu.ac.kr.
authors.forename: Joohyun
authors.initials: J
authors.lastname: Lim
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea. ysung@snu.ac.kr and Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Um
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea. ysung@snu.ac.kr and Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea.
authors.forename: Kyung Jae
authors.initials: KJ
authors.lastname: Lee
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea. ysung@snu.ac.kr and Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea.
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Yu
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 151-747, Korea. jinklee@snu.ac.kr.
authors.forename: Young-Jae
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea. ysung@snu.ac.kr and Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea.
authors.forename: Yung-Eun
authors.initials: YE
authors.lastname: Sung
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 151-747, Korea. jinklee@snu.ac.kr.
authors.forename: Jin-Kyu
authors.initials: JK
authors.lastname: Lee