Electrochemical performance and structure evolution of core-shell nano-ring α-Fe 2 O 3 @Carbon anodes for lithium-ion batteries
Electrochemical performance and structure evolution of core-shell nano-ring α-Fe 2 O 3 @Carbon anodes for lithium-ion batteries
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DOI：
10.1016/j.apsusc.2016.08.071
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发表时间：
2016-12
影响因子：
6.7
通讯作者：
Yanhui Sun;Shan Liu;Feng-Chen Zhou;J. Nan
中科院分区：
文献类型：
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作者：
Yanhui Sun;Shan Liu;Feng-Chen Zhou;J. Nan
采用水热法制备了不同碳含量(5%C和13%C)的核壳纳米环α-Fe_2O_3@碳(α-Fe2O_3@C)复合材料。与裸纳米环α-Fe_2O_3(BNR)相比，CSNR电极的比容量、循环稳定性和倍率性能都有了很大的提高，这归功于CSNR的核壳纳米环结构。复合材料内、外表面的碳壳结构可以提高电极的电子电导率，抑制α-Fe2O3在放电/充电过程中的体积变化，纳米环结构也可以缓冲这种体积变化。CsnR-5%C电极在500mA/−1(0.5C)下循环200次后，首次放电/充电容量达到1570/1220mAhg−1，循环200次后仍保持920/897mAhg−1。即使在2000mA/−1(2C)下，电极的初始容量仍为1400/900mAhg−1,200次循环后仍保持630/610mAhg−1。核壳纳米环在循环过程中打开，重建了由α-Fe_2O_3@碳纳米片组成的新的花朵状结构。纳米片状网络之间的间距可以进一步缓冲α-Fe2O_3的体积膨胀，促进电子和Li+离子在充放电过程中的传输，从而提高电极的容量和倍率能力。首次报道了核壳结构的α-Fe_2O_3@碳在锂/脱锂过程中向花状网络的演化。
Core-shell nano-ring α-Fe2O3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe2O3nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe2O3(BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe2O3during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g−1and retains 920/897 mAh g−1after 200 cycles at 500 mA g−1(0.5C). Even at 2000 mA g−1(2C), the electrode delivers the initial capacities of 1400/900 mAh g−1, and still maintains 630/610 mAh g−1after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe2O3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe2O3and facilitate the transportation of electrons and Li+ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe2O3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.