title: Enhanced Electrochemical Performance of Ultracentrifugation-Derived nc-Li3VO4/MWCNT Composites for Hybrid Supercapacitors.
abstract: Nanocrystalline Li3VO4 dispersed within multiwalled carbon nanotubes (MWCNTs) was prepared using an ultracentrifugation (uc) process and electrochemically characterized in Li-containing electrolyte. When charged and discharged down to 0.1 V vs Li, the material reached 330 mAh g(-1) (per composite) at an average voltage of about 1.0 V vs Li, with more than 50% capacity retention at a high current density of 20 A g(-1). This current corresponds to a nearly 500C rate (7.2 s) for a porous carbon electrode normally used in electric double-layer capacitor devices (1C = 40 mA g(-1) per activated carbon). The irreversible structure transformation during the first lithiation, assimilated as an activation process, was elucidated by careful investigation of in operando X-ray diffraction and X-ray absorption fine structure measurements. The activation process switches the reaction mechanism from a slow "two-phase" to a fast "solid-solution" in a limited voltage range (2.5-0.76 V vs Li), still keeping the capacity as high as 115 mAh g(-1) (per composite). The uc-Li3VO4 composite operated in this potential range after the activation process allows fast Li(+) intercalation/deintercalation with a small voltage hysteresis, leading to higher energy efficiency. It offers a promising alternative to replace high-rate Li4Ti5O12 electrodes in hybrid supercapacitor applications.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Iwama
authors.forename: Nozomi
authors.initials: N
authors.lastname: Kawabata
authors.forename: Nagare
authors.initials: N
authors.lastname: Nishio
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Kisu
authors.forename: Junichi
authors.initials: J
authors.lastname: Miyamoto
authors.affiliation: Division of Art and Innovative Technologies, K&W Inc. , 1-3-16-901 Higashi, Kunitachi, Tokyo 186-0002, Japan.
authors.forename: Wako
authors.initials: W
authors.lastname: Naoi
authors.affiliation: CIRIMAT, Université de Toulouse, CNRS, INPT, UPS , 118 route de Narbonne, 31062 Toulouse cedex 9, France.|Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Rozier
authors.affiliation: CIRIMAT, Université de Toulouse, CNRS, INPT, UPS , 118 route de Narbonne, 31062 Toulouse cedex 9, France.|Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Simon
authors.affiliation: Division of Art and Innovative Technologies, K&W Inc. , 1-3-16-901 Higashi, Kunitachi, Tokyo 186-0002, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Naoi
keywords: Li3VO4; hyperdispersion; initial electrochemical activation; ultracentrifugation; ultrafast charge storage; varied energy efficiency