Defect engineering induced heterostructure of Zn-birnessite@spinel ZnMn2O4 nanocrystal for flexible asymmetric supercapacitor
Defect engineering induced heterostructure of Zn-birnessite@spinel ZnMn2O4 nanocrystal for flexible asymmetric supercapacitor
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缺陷工程诱导柔性非对称超级电容器用锌水钠锰矿@尖晶石型锌锰氧化物纳米晶的异质结构
DOI：
10.1016/j.cej.2021.133115
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发表时间：
2022-02
影响因子：
15.1
通讯作者：
Lulu Lyu;C. Kim;K. Seong;Jeongmin Kang;Shude Liu;Y. Yamauchi;Yuanzhe Piao
中科院分区：
文献类型：
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作者：
Lulu Lyu;C. Kim;K. Seong;Jeongmin Kang;Shude Liu;Y. Yamauchi;Yuanzhe Piao
缺陷工程在提高赝电容材料的表面电荷氧化还原化学方面有很大的希望。然而，它们在异质结构上的创新发展还很欠缺。本文采用低温原位化学还原法制备了富缺陷非均相Zn-birnessite纳米片@尖晶石ZnMn 2 O 4复合材料。我们探讨了锌水钠锰矿中氧空位（Vo）的产生引发Mn阳离子迁移，导致水钠锰矿向尖晶石相变的形成机制。富缺陷的异质结构提供丰富的Mn 2 +/3+/4+氧化还原对，多个电化学活性位点，和缩短的离子传输途径。此外，引入Vo后，异质结构的带隙从1.54 eV减小到1.06 eV，这促进了电子传输，从而支持快速氧化还原反应动力学。因此，该异质结构在1.2 V的宽电位窗口、高倍率性能和长循环寿命（在16，000次循环中保持93.7%的电容）下，在3 mA cm− 2时提供1903 mF cm− 2的大面积电容。采用异质结构作为阴极和氧化钒作为阳极的非对称超级电容器表现出2.4V的高电压，并且具有6.24mWh cm-3的最大能量密度。这项研究提供了一个有前途的途径，通过缺陷工程定制的异质结构的电化学反应。
Defect engineering holds great promise to boost surface charge redox chemistry of pseudocapacitive materials. However, their innovative development on the heterogeneous structure is still lacking. Herein, defect-rich heterogeneous Zn-birnessite nanosheet@spinel ZnMn2O4nanocrystal composites are designed via anin situchemical reduction route at a low temperature. We explore the formation mechanism that the generated oxygen vacancy (Vo) in the Zn-birnessite triggers Mn cation migration, leading to birnessite-to-spinel phase transition. The defect-rich heterostructure supplies rich Mn2+/3+/4+redox couples, multiple electrochemically active sites, and shortened ion-transport pathways. Moreover, the bandgap of the heterostructure is reduced from 1.54 eV to 1.06 eV after introducing Vo, which promotes electron transport and thus bolsters fast redox reaction kinetics. Accordingly, the heterostructure delivers a large areal capacitance of 1903 mF cm−2at 3 mA cm−2at a wide potential window of 1.2 V, high rate performance, and long cycle life (93.7% capacitance retention over 16,000 cycles). An asymmetric supercapacitor employing the heterostructure as a cathode and vanadium oxide as an anode exhibits a high voltage of 2.4 V, and possesses a maximum energy density of 6.24 mWh cm−3. This research offers a promising avenue to tailor the electrochemical reactivity of heterostructures through defect engineering.