【摘要】 采用氧化还原水热法合成二氧化锰。研究了在氧化剂及反应温度等条件相同的情况下,不同反应时间和还原剂对二氧化锰晶型及电化学性能的影响。通过对产物进行XRD分析发现,还原剂为MnSO4时,仅生成单相α-MnO2;而在Mn(NO3)2和MnCl2溶液中,随着反应时间由2～24 h增加到48 h,产物由含有γ-MnO2的α-MnO2转变为单相β-MnO2。对反应时间为12 h生成的二氧化锰进行了循环充放电测试。结果显示,在Mn(NO3)2和MnCl2溶液中生成的含有γ-MnO2的α-MnO2,其初次放电容量分别为203和186.3 mA.h/g,均比在MnSO4溶液中生成的单相α-MnO2的容量140 mA.h/g高;7次循环充放电后,在Mn(NO3)2,MnCl2和MnSO4溶液中生成的MnO2的容量分别保持在初次放电容量的51%,54%和49%。更多还原

【Abstract】 Manganese dioxide(MnO2) was prepared by the redox-based hydrothermal method.With the same oxidant and reaction temperature,the effects of reaction time and Mn(Ⅱ) compounds reductant,including MnSO4,Mn(NO3)2 and MnCl2,on the structure and electrochemical characteristics of obtained MnO2 were studied.Through performing XRD analysis,it was found that only single phase α-MnO2 is formed in the MnSO4 solution.However,in both the Mn(NO3)2 and MnCl2 solution,the product changes from the mixture of α-MnO2 and γ-MnO2 to single phase β-MnO2 when the reaction time increases from 2～24 h to 48 h.Charge-discharge cycle test was performed for the MnO2 prepared with a reaction time of 12 h.The results show that the initial discharge capacities of the mixture of α-MnO2 and γ-MnO2 formed in the Mn(NO3)2 and MnCl2 solution are 203 and 186.3 mA.h/g,respectively,higher than that of single phase α-MnO2(140 mA.h/g) formed in the MnSO4 solution.After 7 charge-discharge cycles,the capacities of MnO2 formed in the Mn(NO3)2,MnCl2 and MnSO4 solution are maintained at a level of 51%,54% and 49% of their initial discharge capacities,respectively.更多还原