Construction of NiCo-Layered Double Hydroxide Microspheres from Ni-MOFs for High-Performance Asymmetric Supercapacitors,ACS Applied Energy Materials

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Construction of NiCo-Layered Double Hydroxide Microspheres from Ni-MOFs for High-Performance Asymmetric Supercapacitors
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2020-06-26 00:00:00 , DOI: 10.1021/acsaem.0c00790
Rajendran Ramachandran _{1,

2,

3} , Yangchun Lan ₂ , Zong-Xiang Xu ₃ , Fei Wang _{2,

4}

Affiliation

Layered double hydroxide (LDH) materials, especially metal–organic framework (MOF)-derived LDHs, have attracted much attention in electrochemical capacitor applications. However, the construction of porous three-dimensional microsphere architectures with controlled morphology is highly demanded for high-performance supercapacitor electrodes. Thus, a simple and effective strategy is recommended to design and fabricate the well-defined layered structure of LDHs with high performance. In this study, we demonstrate the synthesis of nickel–cobalt-LDHs (NiCo-LDHs) by in-situ etching of the Ni-MOF template at different hydrolysis times. Based on the different characterization results of the sample, a formation mechanism has been proposed in terms of the proton production rate and etching process. As a result of the disparity in the layered structure and the surface area, the electrochemical behavior of the NiCo-LDHs has been altered. The sample NiCo-LDH/10 (prepared after the 10 h reaction) exhibited a high surface area and the large size of LDH sheets on microspheres, which promoted the rapid electrolyte ion transportation for supercapacitors and displayed a maximum specific capacity of 1272 C g^–1 at 2 A g^–1. In addition, the assembled asymmetric supercapacitor delivered a remarkable energy density of 36.1 Wh kg^–1 with an outstanding cyclic stability (103.9% after 5000 cycles). This work establishes an effective strategy to synthesize a well-defined NiCo-LDH structure from the MOF template toward high-performance asymmetric supercapacitors, which could be extended to large-scale preparation of other transition metal-based LDHs from Ni-MOFs.

中文翻译：

用于高性能不对称超级电容器的Ni-MOF制备NiCo层状双氢氧化物微球

层状双氢氧化物（LDH）材料，尤其是金属有机骨架（MOF）衍生的LDH，在电化学电容器应用中引起了广泛的关注。然而，对于高性能超级电容器电极，强烈要求构造具有受控形态的多孔三维微球结构。因此，建议采用一种简单有效的策略来设计和制造具有高性能的LDH的分层结构。在这项研究中，我们证明了通过在不同水解时间对Ni-MOF模板进行原位蚀刻可以合成镍-钴-LDHs（NiCo-LDHs）。基于样品的不同表征结果，从质子产生速率和蚀刻工艺方面提出了形成机理。由于层状结构和表面积的差异，NiCo-LDHs的电化学行为已改变。NiCo-LDH / 10（10小时反应后制得）样品具有较高的表面积和微球上LDH片的较大尺寸，从而促进了超级电容器的电解质离子快速迁移，并显示出最大比容量为1272 C g^–1在2 A g ^–1。此外，组装的非对称超级电容器可提供36.1 Wh kg ^–1的出色能量密度，并具有出色的循环稳定性（5000次循环后为103.9％）。这项工作建立了一种有效的策略，可以从MOF模板向高性能不对称超级电容器合成定义明确的NiCo-LDH结构，该结构可以扩展到从Ni-MOF大规模制备其他基于过渡金属的LDH。

更新日期：2020-06-26

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