The four α-cobalt hydroxides (green or blue) with different intercalated anions were synthesized by a chemical precipitation route in which polyethylene glycol was used as the structure-directing reagent for application in the electrode materials of electrochemical capacitors. Every one among the four samples displays an interesting and distinctive morphology although the synthesis conditions were the same except for the anions. The intercalated anions have a critical effect on the basal plane spacing, morphologies, and capacitive properties of the products. Structural and morphological characterizations were performed by using power X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The component and thermal stability of the sample were respectively measured by FT-IR and thermal analyses, including thermogravimetry (TG) and differential thermogravimetry (DTG). The electrochemical behaviors were measured by cyclic voltammogram and galvanostatic charge−discharge. The specific capacitance is up to 697 F g−1 at a charge−discharge current density of 1 A g−1 for the sample with intercalated chlorine. But the sample with intercalated sulfate, which has small crystalline size, more disordered structure, and almost perfect alveolate nanostructure with a large surface area, exhibits relatively poor specific capacitance (420 F g−1). The exceptive phenomena caused by intercalated anions were explained by hydrogen bonding and electrostatic forces. Moreover, the relationships between the specific capacitance, basal plane spacing, as well as the content of the interlayer water were discussed in detail for the four as-synthesized samples.

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A three-dimensional (3D) lamellar SnO2 is grown on carbon cloth (CC) substrate (donated as 3D lamellar SnO2/CC) through hydrothermal reactions and subsequent thermal treatments. The resulting 3D lamellar SnO2/CC can be directly used as electrode of supercapacitors with no need for addition of either binder or conductive species, and achieve a specific capacitance as high as 247 F g -1 at a current density of 1 A g -1 within a potential window ranging from -0.6 to 0.3 V because of the unique porous structure accessible to electrolyte ions. In order to match the capacitive behaviors of 3D lamellar SnO2/CC in the two-electrode systems, reduced graphene oxide/carbon cloth (rGO/CC) is prepared by starting from GO. The rGO/CC and 3D lamellar SnO2/CC are respectively used as positive and negative electrode to assemble asymmetric supercapacitor. The device exhibits not only an excellent cycle stability (76.9 % after 10000 cycles at 3 A g -1 ), but also high energy density of 22.8 Wh kg -1 at the power density of 850 W kg -1 under a cell voltage of 1.7 V. Moreover, the as-fabricated supercapacitor has green and environmentally friendly features because aqueous neutral electrolyte is employed in it.

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Redox-active covalent organic frameworks (COFs) are an emerging class of energy storage materials with notably abundant active sites, well-defined 1D channels and highly surface areas. However, during the process of...

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