期刊
ACS NANO
卷 14, 期 10, 页码 12719-12731出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.0c02973
关键词
current collector; supercapacitors; vertically aligned arrays; NiCo2S4 nanoflakes; thickness independence
类别
资金
- National Key R&D Program of China [2018YFB1105400]
- Natural Science Foundation of Jiangsu Province [BK20161396]
- Key Research and Development Program of Jiangsu Provincial Department of Science and Technology of China [BE2019002, BE2020684]
- National Natural Science Foundation of China [51721001]
- Fundamental Research Funds for the Central Universities [14380163, 14913411]
Pseudocapacitance holds great promise for energy density improvement of supercapacitors, but electrode materials show practical capacity far below theoretical values due to limited ion diffusion accessibility and/or low electron transferability. Herein, inducing two kinds of straight ion-movement channels and fast charge storage/delivery for enhanced reaction kinetics is proposed. Very thick electrodes consisting of vertically aligned and ordered arrays of NiCo2S4-nanoflake-covered slender nickel columns (NCs) are achieved via a scalable route. The vertical standing similar to 5 nm ultrathin NiCo2S4 flakes build a porous covering with straight ion channels without the dead volume, leading to thickness-independent capacity. Benefiting from the architecture acting as a superhighway for ultrafast ion/electron transport and providing a large surface area, high electrical conductivity, and abundant availability of electrochemical active sites, the NiCo2S4@NC-array electrode achieves a specific capacity up to 486.9 mAh g(-1). The electrode even can work with a high specific capacity of 150 mAh g(-1) at a very high current density of 100 A g(-1). In particular, due to the advanced structure features, the electrode exhibits excellent flexibility with a unexpected improvement of capacity when being largely bent and excellent cycling stability with an obvious resistance decrease after the cycles. An asymmetric pseudocapacitor applying the NiCo2S4@NC-array as a positive electrode achieves an energy density of 66.5 Wh kg(-1) at a power density of 400 W kg(-1), superior to the most reported values for asymmetric devices with NiCo2S4 electrodes. This work provides a scalable approach with mold-replication-like simplicity toward achieving thickness-independent electrodes with ultrafast ion/electron transport for energy storage.
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