CAJ | 학술논문

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MnSO_4时,仅生成单相α-MNO_2;而在Mn(NO_3)_2和MnCl_2溶液中,随着反应时间由2～24 h增加到48 h,产物由含有γ-MNO_2的α-MNO_2转变为单相β-MNO_2.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(NO_3)_2和MnCl_2溶液中生成的含有γ-MNO_2的α-MNO_2,其初次放电容量分别为203和186.3 mA·h/g,均比在MnSO_4溶液中生成的单相α-MNO_2的容量140 mA·h/g高;7次循环充放电后,在Mn(NO_3)_2,MnCl_2和MnSO_4溶液中生成的MNO_2的容量分别保持在初次放电容量的51%,54%和49%.
채용양화환원수열법합성이양화맹.연구료재양화제급반응온도등조건상동적정황하,불동반응시간화환원제대이양화맹정형급전화학성능적영향.통과대산물진행XRD분석발현,환원제위MnSO_4시,부생성단상α-MNO_2;이재Mn(NO_3)_2화MnCl_2용액중,수착반응시간유2～24 h증가도48 h,산물유함유γ-MNO_2적α-MNO_2전변위단상β-MNO_2.대반응시간위12 h생성적이양화맹진행료순배충방전측시.결과현시,재Mn(NO_3)_2화MnCl_2용액중생성적함유γ-MNO_2적α-MNO_2,기초차방전용량분별위203화186.3 mA·h/g,균비재MnSO_4용액중생성적단상α-MNO_2적용량140 mA·h/g고;7차순배충방전후,재Mn(NO_3)_2,MnCl_2화MnSO_4용액중생성적MNO_2적용량분별보지재초차방전용량적51%,54%화49%.
Manganese dioxide (MNO_2) 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 MnSO_4,Mn(NO_3)_2 and MnCl_2,on the structure and electrochemical characteristics of obtained MNO_2 were studied.Through performing XRD analysis,it was found that only single phase α-MNO_2 is formed in the MnSO_4 solution.However,in both the Mn(NO_3)_2 and MnCl_2 solution,the product changes from the mixture of α-MNO_2 and γ-MNO_2 to single phase β-MNO_2 when the reaction time increases from 2～24 h to 48 h.Charge-discharge cycle test was performed for the MNO_2 prepared with a reaction time of 12 h.The results show that the initial discharge capacities of the mixture of α-MNO_2 and γ-MNO_2 formed in the Mn(NO_3)_2 and MnCl_2 solution are 203 and 186.3 mA·h/g,respectively,higher than that of single phase α-MNO_2 (140 mA·h/g) formed in the MnSO_4 solution.After 7 charge-discharge cycles,the capacities of MNO_2 formed in the Mn(NO_3)_2,MnCl_2 and MnSO_4 solution are maintained at a level of 51%,54% and 49% of their initial discharge capacities,respectively.