| Supercapacitor(ECs)is a new type of green energy storage device,and it stores energy primarily through polarized electrolytes.Because it has many advantages such as high energy density,excellent circulation performance(recycled more than 100000 times)and other advantages,it plays an important role in the growing energy demand and reducing the pressure of the ecological environment.Usually,transition metal oxides(such as:MnO2,NiO,RuO2,Co3O4 etc.)can be used as super capacitor electrode materials.Because they have 2 to 3 times more capacitances than the carbon/graphene electrode materials,so is often seen as a valuable electrode material for research.In the transition metal oxides,the MnO2 which can still have a larger voltage window in neutral electrolyte that compared with other metal oxides which should be carried out in the strong acid or alkali solution to electrochemical reaction has great advantages.so the MnO2 as supercapacitor electrode material is more worthy of our study.The template method is the simplest of the many methods to synthesize manganese dioxide,but most of the experiments require heating or water bath treatment.By using the sacrificial template method,a relatively homogeneous manganese dioxide spherical shell with an area of 66.17 m2g-1 was synthesized by using colloidal carbon spheres as the template react with potassium permanganate at normal temperature.This paper mainly studies that the conditions for the synthesis of manganese dioxide from the reaction of ZIF-67 with potassium permanganate and the reaction of RF resin with potassium permanganate.The electrochemical properties of these materials were studied.The main work is as follows:1.SiO2@RF was synthesized by using the principle that tetraethyl orthosilicate(TEOS),resorcinol and formaldehyde can be nucleated in solution.After removing SiO2 with HF,the RF resin bowl was obtained.Two kinds of RF resin bowl precursors were obtained by treating or untreating RF resin bowl.Using the two kinds of precursor reacted with potassium permanganate solution respectively that can synthesize the hollow MnO2 nanospheres and MnO2 nano-bowl whose specific surface area were 34.4 m2g-1 and 52.4 m2g-1.The annealing treatment of MnO2 nano-bowl with different temperature was carried out.MnO2 nano-bowls with different annealing temperatures can be obtained by treating with 200 ?,300 ?,400 ? and 500 ?.Electrochemical tests were performed on these MnO2 materials.It is found that the electrochemical properties of MnO2 nano-bowl are better than those of hollow MnO2 nanospheres and for MnO2 nano-bow,the electrochemical properties were the best after 300 ? annealing.At the current density of 0.5Ag-1,the specific capacity was 254 Fg-1,and at the 5Ag-1 current density the capacity was still 92.8%at the 5Ag-1 current density after the 3,000 times cycling.2.The ZIF-67 precursors were formed by the ligation of cobalt nitrate hexahydrate and 2-methyl imidazole under the action of the active agent hexadecyl trimethylammonium bromide(CTAB).Controling the quality ratio of potassium permanganate and ZIF-67 were 1:1,1:3,1:9 and 1:16 respectively and using "sacrifice template method",made ZIF-67 reacting with potassium permanganate solution at room temperature to form MnO2 nano-boxes.And through water bath and annealing two ways to remove residual organic matter in the MnO2 nano-boxes,to synthesis different thickness hollow MnO2 nano-boxes that doped N,C,Co elements.And electrochemical properties of those hollow manganese dioxide nano-boxes were tested and it was found that whether through water bath and annealing to remove organic matter,when in the reaction mass ratio of potassium permanganate and ZIF-67 was1:16 electrochemical performance of the hollowMnO2 nano-boxes was best.And the electrochemical properties of the hollow MnO2 nano-boxes formed by annealing treatment were better than the hollow MnO2 nano-boxes formed after the treatment of water bath.The specific surface area of the hollow MnO2 nano-boxes obtained by water bath treatment and annealing treatment was 126.39 m2g'1 and 98.86 m2g-1 respectively when the reactant mass ratio was 1:16.And at the current density of 1 Ag-1,their specific capacity is 110.1 Fg-1 and 137.6 Fg-1 respectively,and at the 5Ag-1 current density the capacity of can be maintained at 93.2%and 91.2%respectively after the 3,000 times cycling. |
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