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新型Fe_2O_3纳米电极材料的设计合成及其在柔性非对称超级电容器中的应用研究
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摘要
近几年来,相比正极材料,混合型电容器的负极材料的发展则相对缓慢~([1])。在众多的负极材料中,三氧化二铁(Fe_2O_3)不但具有较高的电容性能和合适的负电位工作电压,而且资源丰富、价格低廉、环境友好,因而是一种极具发展潜力的高性能负极材料~([2-3])。然而,由于它的弱电导性,导致其倍率性能、能量密度偏低和稳定性较差,严重制约着它在高性能超级电容器中的广泛应用。为了改善Fe_2O_3纳米电极材料的电子传输性能和循环稳定性,我们利用缺陷氛围下的热处理技术在生长在碳布上的α-Fe_2O_3纳米棒中引入一定量的氧空位后,其载流子浓度获得明显的提升,极大地改善了α-Fe_2O_3的电子传输能力~([3])。测试结果表明,引入氧空位后,α-Fe_2O_3的电容性能增加两倍,体积电容达到6.9 F/cm~3(10mV/s)。进一步以氧缺陷型α-Fe_2O_3为负极,研制了一种工作电压为1.6 V,能量密度达到0.41 mWh/cm~(-3)的柔性固态混合型超级电容器。此外,为了更好的控制氧空位的量,我们进一步提出Ti~(4+)掺杂和导电高分子(PEDOT)包覆的策略对α-Fe_2O_3同时进行改性,进一步提升了其储能性能。此外,以PEDOT@Ti-Fe_2O_3核壳纳米棒为负极的柔性非对称电容器件的能量密度高达0.89 mWh/cm~(3[4])。这些工作极大地丰富了混合型超级电容器负极材料。
Over the past few years,compared to cathode materials,the progresses on the anode materials are relatively slow.~([1]) Among them,α-Fe_2O_3 holds great promise as an anode for asymmetric supercapacitors(ASCs) because of its large theoretical capacitance,suitable negative working window,low-cost,abundance and non-toxicity.~([2-3])However,the electrochemical performance of α-Fe_2O_3 electrode is greatly limited due to its poor conductivity.To improve the conductivity and stability of the α-Fe_2O_3 electrode,we demonstrate a simple approach to introduce oxygen vacancies.The oxygen-deficient α-Fe_2O_3 electrode exhibits significantly enhanced capacitance with the highest volumetric capacitance of 6.9 F/cm~3.A flexible ASC based on oxygen-deficient α-Fe_2O_3 electrode achieved a maximum energy density of 0.41 mWh/cm~3.Moreover,we proposed Ti~(4+) doping and PEDOT coating methods to further boost the electrochemical performance of α-Fe_2O_3.The as-fabricated ASC possess a maximum energy density of 0.89 mWh/cm~3.All those work offers new opportunities for anode materials of ASCs.
引文
[1]Wang,G;Zhang,L.;Zhang,J.,Chem.Soc.Rev.,2012,41,797-828.
    [2]Qu,Q.;Yang,S.;Feng,X.,Adv.Mater.,2011,23,5574-5580.
    [3]Lu X,Zeng Y,Yu M,et al.,Adv.Mater.,2014,26,3148-3155.
    [4]Zeng Y,Han Y,Zhao Y,et al.,Adv.Energy Mater.,2015,5,1402176.

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