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硫化钒修饰二氧化钛纳米线阵列作为高性能锂离子电池负极材料
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摘要
目前,以二氧化钛(TiO_2)纳米结构骨架为基础的新型复合纳米材料在电化学储能方面的应用已经引起了人们的广泛关注。作为一种典型的过渡金属二硫化物(TMDS),硫化钒(VS_2)具有类石墨烯的二维层状结构及较大的层间距,单层VS_2具有类金属性的导电性和较低的Li~+扩散势垒以及较高的理论容量,非常适合锂离子的脱嵌。本文采用两步水热法合成了一种独特的VS_2修饰TiO_2纳米线阵列(TVNAs),材料表征结果显示结晶性良好的VS_2纳米粒子均匀地分散在TiO_2纳米线阵列(TNAs)的表面且二者具有很强的结合力。TVNAs具有十分突出的储锂性能,电流密度为1C(1C=300 mAh g~(-1))时,其可逆容量为281.3 mAh g~(-1),经过500次循环之后容量保持率为129.9%,当电流密度增加到10 C时,其容量依然可以达到171.2 mAh g~(-1)。该复合纳米线阵列之所以具有优异的电化学性能,一方面在于TNAs良好的结构稳定性,另一方面则归功于VS_2较高的理论容量、独特的二维结构以及良好的离子扩散和电子传导能力。
Nowadays,the new composite materials based on the skeleton of TiO_2 nanostructure in electrochemistry energy storage have been received more attention.As an typical TMDS,VS_2 have the analogous platelike construction to graphene,the mono-layered structure of VS_2 has a similar or lower Li diffusion barrier and higher theoretical capacity than graphene.This paper reports a unique VS_2 nanoparticles decorated TiO_2 vertical nanowire arrays(TVNAs) by a two-step hydrothermal process.It is found that the crystalline VS_2 nanoparticles uniformly distribute on the surface of the TiO_2 vertical nanowire arrays(TNAs) and adhere strongly to them.The resultant TVNAs show excellent electrochemistry performance including high reversible capacity,long cycle stability and outstanding high-rate capability.The outstanding electrochemistry property of the TVNAs attribute to the stable structure of TNAs and the excellent lithium storage property of VS_2.
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