title: Hybrid nanomaterial of α-Co(OH)2nanosheets and few-layer graphene as an enhanced electrode material for supercapacitors.
abstract: Supercapacitor with metal hydroxide nanosheets as electrode can have high capacitance. However, the cycling stability and high rate capacity is low due to the low electrical conductivity. Here, the exfoliated α-Co(OH)2nanosheets with high capacitance has been assembled on few-layer graphene with high electric conductivity by a facile yet effective and scalable solution method. Exfoliated hydrotalcite-like α-Co(OH)2nanosheets and few-layer graphene suspensions were prepared by a simple ultrasonication in formamide and N-methyl-2-pyrrolidone, respectively. Subsequently, a hybrid was made by self-assembly of α-Co(OH)2and few-layer graphene when the two dispersions were mixed at room temperature. The hybrid material provided a high specific capacitance of 567.1F/g at 1A/g, while a better rate capability and better stability were achieved compared to that mad of pristine and single exfoliated α-Co(OH)2. When the hybrid nanocomposite was used as a positive electrode and activated carbon was applied as negative electrode to assembly an asymmetric capacitor, an energy density of 21.2Wh/kg at a power density of 0.41kW/kg within a potential of 1.65V was delivered. The high electrochemical performance and facile solution-based synthesis method suggested that the hybrid of exfoliated α-Co(OH)2/few-layer graphene could be a potential electrode material for electrochemical capacitor.
authors.affiliation: State Key Laboratory of Silicon Materials, School of Materials Science & Engineering, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Zhejiang University, Hangzhou 310027, China. Electronic address: chengjp@zju.edu.cn.
authors.forename: J P
authors.initials: JP
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Silicon Materials, School of Materials Science & Engineering, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Zhejiang University, Hangzhou 310027, China.
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Silicon Materials, School of Materials Science & Engineering, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Zhejiang University, Hangzhou 310027, China.
authors.forename: K Y
authors.initials: KY
authors.lastname: Ma
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, United States.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, United States.
authors.forename: Q Q
authors.initials: QQ
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, United States.
authors.forename: J S
authors.initials: JS
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Silicon Materials, School of Materials Science & Engineering, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Zhejiang University, Hangzhou 310027, China.
authors.forename: F
authors.initials: F
authors.lastname: Liu
keywords: Cobalt hydroxide; Delamination; Electrochemical capacitor; Few-layer graphene