Zhang Xiaofeng, Yang Feng, Chen Haixin, Wang Kun, Chen Junwei, Wang Yi, Song Shuqin
The Key Lab of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, School of Materials Science and Engineering, School of Chemical Engineering and Technology, Sun Yat-sen University, Guangzhou, 510275, China.
College of New Energy and Materials, China University of Petroleum-Beijing, Beijing, 102249, China.
Small. 2020 Nov;16(44):e2004188. doi: 10.1002/smll.202004188. Epub 2020 Oct 12.
In order to further overcome the shortage of electrodes with additive/binder and modulate the structure of NiCo O for supercapacitors, ultrathin NiCo O nanosheet arrays have been in situ grown on Ni foam by optimizing hydrothermal reactions based on crystal growth dynamics. The structure of ultrathin NiCo O nanosheet arrays can expose more active sites, provide abundant diffusion channels and buffer the stress caused by phase transition during charge-discharge process of supercapacitors. The optimized hydrothermal reactions can provide more ordered crystal orientations by keeping nanosheets on Ni foam completely coming from in situ growth, which will decrease the inner resistance of ultrathin NiCo O nanosheets and improve the efficiency and kinetics of electrons transfer. By the virtue of such remarkable features, the electrochemical results confirm the rationality of structural modulation and crystal orientations optimization with a drastically enhanced specific capacitance of 2017.8 F g , admirable rate performance of 93.2% and outstanding stability retention of 90.9% after cycling 5000 times. More impressively, the assembled flexible solid-state asymmetric supercapacitor (ASC) shows superior energy density, power density, and high stability. The modification strategy in this paper may throw light on the rational design of new generation advanced electrode materials for high-performance flexible supercapacitors.
为了进一步克服含添加剂/粘结剂电极的不足，并调控用于超级电容器的NiCoO的结构，基于晶体生长动力学，通过优化水热反应，在泡沫镍上原位生长了超薄NiCoO纳米片阵列。超薄NiCoO纳米片阵列的结构可以暴露出更多活性位点，提供丰富的扩散通道，并缓冲超级电容器充放电过程中相变引起的应力。优化后的水热反应可以通过使泡沫镍上的纳米片完全来自原位生长来提供更有序的晶体取向，这将降低超薄NiCoO纳米片的内阻，提高电子转移的效率和动力学。凭借这些显著特性，电化学结果证实了结构调控和晶体取向优化的合理性，其比电容大幅提高至2017.8 F/g，倍率性能令人钦佩，为93.2%，在循环5000次后具有90.9%的出色稳定性保持率。更令人印象深刻的是，组装的柔性固态不对称超级电容器（ASC）表现出优异的能量密度、功率密度和高稳定性。本文中的改性策略可能为高性能柔性超级电容器新一代先进电极材料的合理设计提供思路。
