Block Copolymer Directed Ordered Mesostructured TiNb2O7 Multimetallic Oxide Constructed of Nanocrystals as High Power Li-Ion Battery Anodes

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• 作者：Changshin Jo ; Youngsik Kim ; Jongkook Hwang ; Jongmin Shim ; Jinyoung Chun ; Jinwoo Lee
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：June 10, 2014
• 年：2014
• 卷：26
• 期：11
• 页码：3508-3514
• 全文大小：469K
• 年卷期：v.26,no.11(June 10, 2014)
• ISSN：1520-5002

文摘

In order to achieve high-power and -energy anodes operating above 1.0 V (vs Li/Li⁺), titanium-based materials have been investigated for a long time. However, theoretically low lithium charge capacities of titanium-anodes have required new types of high-capacity anode materials. As a candidate, TiNb₂O₇ has attracted much attention due to the high theoretical capacity of 387.6 mA h g^鈥?. However, the high formation temperature of the TiNb₂O₇ phase resulted in large-sized TiNb₂O₇ crystals, thus resulting in poor rate capability. Herein, ordered mesoporous TiNb₂O₇ (denoted as m-TNO) was synthesized by block copolymer assisted self-assembly, and the resulting binary metal oxide was applied as an anode in a lithium ion battery. The nanocrystals (15 nm) developed inside the confined pore walls and large pores (40 nm) of m-TNO resulted in a short diffusion length for lithium ions/electrons and fast penetration of electrolyte. As a stable anode, the m-TNO electrode exhibited a high capacity of 289 mA h g^鈥? (at 0.1 C) and an excellent rate performance of 162 mA h g^鈥? at 20 C and 116 mA h g^鈥? at 50 C (= 19.35 A g^鈥?) within a potential range of 1.0鈥?.0 V (vs Li/Li⁺), which clearly surpasses other Ti-and Nb-based anode materials (TiO₂, Li₄Ti₅O₁₂, Nb₂O₅, etc.) and previously reported TiNb₂O₇ materials. The m-TNO and carbon coated m-TNO electrodes also demonstrated stable cycle performances of 48 and 81% retention during 2,000 cycles at 10 C rate, respectively.