Enhanced electrochemical performance of Na2/3[Mn0.55Ni0.30Co0.15]O2 positive electrode in sodium-ion batteries by functionalized multi-walled carbon nanotubes
Enhanced electrochemical performance of Na2/3[Mn0.55Ni0.30Co0.15]O2 positive electrode in sodium-ion batteries by functionalized multi-walled carbon nanotubes
复制标题
DOI：
10.1016/j.electacta.2017.03.204
复制
发表时间：
2017-05
影响因子：
6.6
通讯作者：
V. Rangasamy;Luman Zhang;J. Seo;J. Locquet;Savitha Thayumanasundaram
中科院分区：
文献类型：
--
作者：
V. Rangasamy;Luman Zhang;J. Seo;J. Locquet;Savitha Thayumanasundaram
Nax[MnyNi 1-y-zCoz]O2（NMNC）具有层状氧化物结构和高理论容量（240 mAh g−1），是一种有前途的钠离子电池（SIB）阴极材料。NMNC具有低的电子电导率，这严重影响高电流密度下的电池性能。在这项研究中，我们已经合成了P2相Na 2/3[Mn0.55Ni0.30Co0.15] O2通过溶剂热过程，并使用多壁碳纳米管（MWCNTs）功能化与羧酸基团，以形成一个纳米级的导电网络的材料。我们的研究结果表明，电极动力学是由反应物的质量传输，和多壁碳纳米管促进更好的流动的电子和Na+，特别是在高C率（> 2C）。我们观察到一个较低的电荷转移电阻的复合电极比在原始NMNC。我们还将阴极的Na+扩散系数的差异与其电化学性能相关联。MWCNT的掺入增强了NMNC的高倍率性能，最高可达10 C倍率，并在0.1C倍率下产生150 mAh g− 1的比容量。复合电极的这种高倍率性能和比容量证实了MWCNT可以增强P2-NMNC的电化学性能，并使其成为用于SIB的可行的正极材料。
Nax[MnyNi1-y-zCoz]O2(NMNC), with a layered oxide structure and a high theoretical capacity (240 mAh g−1), is a promising cathode material for sodium-ion batteries (SIBs). NMNC has a low electronic conductivity, which severely affects the cell performance at high current densities. In this study, we have synthesized P2-phase Na2/3[Mn0.55Ni0.30Co0.15]O2by a solvothermal process, and used multi-walled carbon nanotubes (MWCNTs) functionalized with carboxylic acid groups to form a nanoscale conductive network in the material. Our results indicate that the electrode kinetics are governed by the mass transport of the reactants, and MWCNTs facilitate better flow of electrons and Na+, especially at high C rates (> 2C). We observed a lower charge-transfer resistance in the composite electrode than in pristine NMNC. We also correlate the difference in the Na+diffusion coefficients of the cathodes to their electrochemical performance. The incorporation of MWCNT enhanced high rate performance of NMNC up to 10C rate and resulted in a specific capacity of 150 mAh g−1at 0.1C rate. Such high rate capability and specific capacity of the composite electrode confirm that the MWCNTs could enhance the electrochemical performance of the P2-NMNC and make it a viable positive electrode material for SIBs.