title: Facile Synthesis of Nb2O5@Carbon Core-Shell Nanocrystals with Controlled Crystalline Structure for High-Power Anodes in Hybrid Supercapacitors.
abstract: Hybrid supercapacitors (battery-supercapacitor hybrid devices, HSCs) deliver high energy within seconds (excellent rate capability) with stable cyclability. One of the key limitations in developing high-performance HSCs is imbalance in power capability between the sluggish Faradaic lithium-intercalation anode and rapid non-Faradaic capacitive cathode. To solve this problem, we synthesize Nb2O5@carbon core-shell nanocyrstals (Nb2O5@C NCs) as high-power anode materials with controlled crystalline phases (orthorhombic (T) and pseudohexagonal (TT)) via a facile one-pot synthesis method based on a water-in-oil microemulsion system. The synthesis of ideal T-Nb2O5 for fast Li(+) diffusion is simply achieved by controlling the microemulsion parameter (e.g., pH control). The T-Nb2O5@C NCs shows a reversible specific capacity of ∼180 mA h g(-1) at 0.05 A g(-1) (1.1-3.0 V vs Li/Li(+)) with rapid rate capability compared to that of TT-Nb2O5@C and carbon shell-free Nb2O5 NCs, mainly due to synergistic effects of (i) the structural merit of T-Nb2O5 and (ii) the conductive carbon shell for high electron mobility. The highest energy (∼63 W h kg(-1)) and power (16 528 W kg(-1) achieved at ∼5 W h kg(-1)) densities within the voltage range of 1.0-3.5 V of the HSC using T-Nb2O5@C anode and MSP-20 cathode are remarkable.
authors.affiliation: †School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Eunho
authors.initials: E
authors.lastname: Lim
authors.affiliation: ‡Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Changshin
authors.initials: C
authors.lastname: Jo
authors.affiliation: §Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, 599 Gwanak-Ro, Gwanak-Gu, Seoul 151-742, Republic of Korea.
authors.forename: Haegyeom
authors.initials: H
authors.lastname: Kim
authors.affiliation: ∥Energy and Environmental Division, Korea Institute of Ceramic Engineering and Technology (KICET), 101 Soho-Ro, Jinju, Gyeongnam 660-031, Republic of Korea.
authors.forename: Mok-Hwa
authors.initials: MH
authors.lastname: Kim
authors.affiliation: ‡Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Yeongdong
authors.initials: Y
authors.lastname: Mun
authors.affiliation: ‡Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Jinyoung
authors.initials: J
authors.lastname: Chun
authors.affiliation: ‡Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Youngjin
authors.initials: Y
authors.lastname: Ye
authors.affiliation: ‡Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Jongkook
authors.initials: J
authors.lastname: Hwang
authors.affiliation: ⊥Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 121-742, Republic of Korea.
authors.forename: Kyoung-Su
authors.initials: KS
authors.lastname: Ha
authors.affiliation: ∥Energy and Environmental Division, Korea Institute of Ceramic Engineering and Technology (KICET), 101 Soho-Ro, Jinju, Gyeongnam 660-031, Republic of Korea.
authors.forename: Kwang Chul
authors.initials: KC
authors.lastname: Roh
authors.affiliation: §Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, 599 Gwanak-Ro, Gwanak-Gu, Seoul 151-742, Republic of Korea.|¤Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Kisuk
authors.initials: K
authors.lastname: Kang
authors.affiliation: #Department of Integrative Engineering, Chung-Ang University, 221, Heukseok-Dong, Dongjak-Gu, Seoul 156-756, Republic of Korea.
authors.forename: Songhun
authors.initials: S
authors.lastname: Yoon
authors.affiliation: †School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.|‡Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Lee
keywords: controlled crystal structures; core−shell nanostructures; high-power anodes; hybrid supercapacitors; orthorhombic Nb2O5 nanocrystals