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本文详细研究了橄榄石结构磷酸盐脱嵌锂过程的控制步骤,发现就多元橄榄石结构Li(FeMnCo)PO4磷酸盐而言,碳含量比较低时在充放电曲线之间存在非对称现象.充电时与Fe2+/Fe3+电对对应的容量小于理论容量,与Co2+/Co3+电对对应的容量大于理论容量;放电时与Co2+/Co3+电对对应的容量远小于相应的充电容量,但是与Fe2+/Fe3+电对对应的放电容量远大于与该电对对应的充电容量.电极呈现出以Co2+/Co3+电对充电,以Fe2+/Fe3+电对放电的行为.作者认为在充电和放电过程中活性材料颗粒内部存在内界面,充电时内界面内部组成是Fe2+、Co2+、Mn2+和低浓度的Fe3+,而内界面外部组成是Co3+、Mn2+、Fe3+和低浓度的Co2+.非对称现象的主要原因是内界面移动速度缓慢,碳含量低时慢的内界面移动速度是电化学脱嵌锂过程的主要控制步骤. 相似文献
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基于碳纳米管独特的结构特点建立了以其为基础的Pocklington积分方程,并设计了一种全新的碳纳米管太赫兹(THz)波天线.数值仿真和理论计算结果表明,碳纳米管能够产生高频THz电磁辐射,半波长为60μm、半径为2.712nm的单壁碳纳米管偶极天线在-10dB反射系数以下可以实现2.5THz与7.6THz的双频带工作,带宽分别为8.4%与2.7%,由其构成的纳米管天线阵可以获得10.3dB的高增益特性.所得结果有助于在纳观域开展高频THz波辐射源及天线的研究与设计.
关键词:
太赫兹波
碳纳米管
天线
辐射源 相似文献
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An analytical solution is presented for the electromagnetic scattering from an infinite-length metallic carbon nanotube and a carbon nanotube bundle.The scattering field and scattering cross section are predicted using a modal technique based on a Bessel and Hankel function for the electric line source and a quantum conductance function for the carbon nanotube.For the particular case of an isolated armchair (10,10) carbon nanotube,the scattered field predicted from this technique is in excellent agreement with the measured result.Furthermore,the analysis indicates that the scattering pattern of an isolated carbon nanotube differs from that of the carbon nanotube bundle of identical index (m,n) metallic carbon nanotubes. 相似文献
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Characterization of the radiation from single-walled zig-zag carbon nanotubes at terahertz range
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This paper investigates the radiation characteristics of
metal single-walled zig-zag carbon nanotubes as a dipole antenna at
terahertz wave range. The current distribution, input impedance and
mutual impedance are calculated for various geometrical parameters
of vertically-aligned carbon nanotubes. The numerical results
demonstrate the properties of the antenna depending strongly on the
geometrical parameters such as the radius, the lengths of carbon
nantobues, and the spacing between nanotubes. It is found that the
zig-zag carbon nanotubes exhibit very high input impedance and the
mutual impedances for antenna array applications. These unique high
impedance properties are different from the conventional metal thin
wire antenna. The far-field patterns and gain of antenna array are
also calculated. The maximum gain of array of 100-element array is
up to 20.0~dB, which is larger than the gain of 0.598~dB of single
dipole antenna at distance d = 0.5\lambda . 相似文献