Facile Synthesis of Nb2O5@Carbon Core鈥揝hell Nanocrystals with Controlled Crystalline Structure for High-Power Anodes in Hybrid Supercapacitors

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• 作者：Eunho Lim ; Changshin Jo ; Haegyeom Kim ; Mok-Hwa Kim ; Yeongdong Mun ; Jinyoung Chun ; Youngjin Ye ; Jongkook Hwang ; Kyoung-Su Ha ; Kwang Chul Roh ; Kisuk Kang ; Songhun Yoon ; Jinwoo Lee
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：July 28, 2015
• 年：2015
• 卷：9
• 期：7
• 页码：7497-7505
• 全文大小：625K
• ISSN：1936-086X

文摘

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鈥搒hell 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 鈭?80 mA h g^鈥? at 0.05 A g^鈥? (1.1鈥?.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 (鈭?3 W h kg^鈥?) and power (16鈥?28 W kg^鈥? achieved at 鈭? W h kg^鈥?) densities within the voltage range of 1.0鈥?.5 V of the HSC using T-Nb₂O₅@C anode and MSP-20 cathode are remarkable.