With using manganese sulfate monohydrate as manganese source and ammonium persulfate as oxidant,five MnO2 products were prepared by a hydrothermal synthesis method at the reaction temperature of 100,120,140,160 and 180℃,respectively.The results of XRD,SEM and supercapacitor performance tests shown that the reaction temperature directly affected the crystal form,morphology and supercapacitor properties of MnO2 products.When the reaction temperature was in the range of 100~120℃,the as-prepared MnO2 (S1 and S2) were consisted of α+γ crystal and in the morphology of aggregated spheres.As the temperature was in the range of 140~180℃,MnO2 products (S3~S5) with the crystal form of α+β and the morphology of rods were synthesized;furthermore,with the increasing of reaction temperature from 140 to 180℃,the rod diameter was found to be gradually increased from 0.18 to 0.51 μm,as well as the α-form content was proved to be gradually decreased from 77.8% to 57.5%.As far as supercapacitor properties are concerned,the rod-like products (S3-S5) exhibits higher specific capacitance,coulombic efficiency and capacitance retention than those aggregated sphere-like products (S1 and S2).Among the rod-like products,product S3 which with the smallest rod diameter and the highest α-form content appeared the best supercapacitor behavior.
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