Intrinsic conductivity optimization of bi-metallic nickel cobalt selenides toward superior-rate Na-ion storage,Materials Chemistry Frontiers

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Intrinsic conductivity optimization of bi-metallic nickel cobalt selenides toward superior-rate Na-ion storage
Materials Chemistry Frontiers ( IF 6.0 ) Pub Date : 2017-10-19 00:00:00 , DOI: 10.1039/c7qm00419b
Chen Wu _{1,

2,

3,

4} , Yuehua Wei _{1,

2,

3,

4} , Qingwang Lian _{1,

2,

3,

4} , Chao Cui _{1,

2,

3,

4} , Weifeng Wei _{1,

2,

3,

4} , Libao Chen _{1,

2,

3,

4} , Chengchao Li _{4,

5,

6,

7}

Affiliation

Enhancing the conductivity of electrode materials is critically important for improving the high-rate performance of Na-ion batteries (NIBs). Herein, we report a multifaceted strategy for optimizing the conductivity and electrochemical properties of nickel cobalt selenides via the combination of fine component regulation and C coating. The electrical conductivity of C@Ni_0.33Co_0.67Se₂/C nanofiber (CNF) (Co_0.67) hybrids achieved in this study was 0.3733 S mm⁻¹, a conductivity five-fold higher than that of selenides with a Ni/Co ratio of 2 : 1. Coupled with desirable three-dimensional (3D) nanobrush morphology and the 1D conducting path of CNFs, the Co_0.67 electrode achieved a superior rate performance of 413.1 mA h g⁻¹, even at 2 A g⁻¹. Furthermore, the Co_0.67 electrode exhibited an impressive cycling performance of 499 mA h g⁻¹ after 100 cycles (exhibiting an 89.5% capacity retention of the second cycle). Finally, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry analysis at different sweep rates were conducted to demonstrate the Co_0.67 electrode's fast charge/ion transport ability and increased electrode kinetics.

中文翻译：

双金属硒化镍钴对高速率Na离子存储的本征电导率优化

增强电极材料的电导率对于改善Na-离子电池（NIB）的高倍率性能至关重要。本文中，我们报告了通过精细组分调节和C涂层相结合来优化硒化镍钴的电导率和电化学性能的多方面策略。在这项研究中获得的C @ Ni _0.33 Co _0.67 Se ₂ / C纳米纤维（CNF）（Co _0.67）杂化物的电导率为0.3733 S mm ^-1，比具有Ni / Co比的硒化物的电导率高五倍之2：1.结合所需的三维（3D）纳米刷形态和CNF的1D传导路径，Co _0.67即使在2 A g ^{-1的情况下}，该电极也能达到413.1 mA hg ^-1的优异倍率性能。此外，Co _0.67电极在100个循环后表现出令人印象深刻的499 mA hg ^-1的循环性能（显示出第二个循环的89.5％的容量保持率）。最后，在不同的扫描速率下进行了电化学阻抗谱（EIS）和循环伏安分析，以证明Co _0.67电极的快速电荷/离子传输能力和增强的电极动力学。

更新日期：2017-10-30

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