【作者】 艾娟；

【导师】 徐徽；

【作者基本信息】 中南大学 ， 冶金物理化学， 2003， 硕士

【摘要】 本文以研究开发具有实用价值和应用前景的无汞可充碱锰电池正极材料为主要目的，采用化学分析、X-射线衍射分析（XRD）、扫描电镜（SEM）、充放电性能测试、动电位扫描等多种化学与电化学研究手段及现代波谱技术，选择高锰酸钾（KMnO₄）法和碳酸锰（MnCO₃）热分解两种方法，对无汞可充碱锰电池正极活性物质二氧化锰的制备、掺杂及应用进行了重点研究，同时从理论上分析和探讨了二氧化锰经化学掺杂改性后对其充放电机理和充放电性能的影响规律。本文还对无汞可充碱锰电池电解液及其添加剂进行初步的研究和探索。 高锰酸钾（KMnO₄）氧化法制备化学二氧化锰，是将一定浓度的高锰酸钾溶液与氯化锰溶液直接反应而得到二氧化锰粉末。该方法具有流程短、能耗低、工艺条件易于控制等优点。通过试验，得到制备化学改性二氧化锰的最佳工艺参数为：反应温度为85℃；反应时间为1小时；硝酸浓度为0.5～1mol／L；锰盐为MnCl₂；掺杂物为Bi（No）₃；Mn：Bi的摩尔比为6～10。充放电性能测试表明：该法制备的化学二氧化锰电化学性能优于电解二氧化锰；掺Bi的改性二氧化锰经过10次全充全放破坏性充放电循环后，放电容量还有首次放电容量的70％，10次累积放电容量是未掺杂样品的3.26倍。X-射线衍射结果表明：MnO₂样品是β-MnOOH为主的混合晶相。但高锰酸钾（KMnO₄）氧化法存在一个问题，就是生产出来的改性化学二氧化锰的振实密度难以提高，达不到电池材料高振实密度、高填充性的要求。 为进一步提高改性化学二氧化锰的振实密度并改善其电化学性能，还研究了碳酸锰（MnCO₃）热分解法制备化学二氧化锰。该方法是先用碳酸氢铵作沉淀剂，以前一次的产物作为下一次反应的晶种，累计沉淀，制备出高振实密度的晶种碳酸锰，再改用碳酸钠作为沉淀剂，这样既提高了碳酸根的利用率，又达到了高振实密度的目的；制出的碳酸锰在高温、湿空气气氛下氧化分解成粗二氧化锰；再通过氯酸钠氧化生成最终成品。通过试验，得到制备化学改性二氧化锰的最佳工艺参数为：视密中南大学硕士研究生毕业论文度达2 .00g/cm’以上的晶种加人量为理论产量的50%（质量百分数）;碳酸锰沉淀温度为40‘C;沉淀时间为1 .5小时;焙烧温度以375OC一390℃最佳;碳酸锰焙烧时间为8小时;空气中水汽含量约为47%;精制时分批加人固体粉末的氯酸钠进行氧化，其用量为理论量的11。%，反应温度为90℃，反应2 .5一3小时;掺杂物为Bi（N0）。;Mn:Bi的摩尔比6一1。。该方法制备的化学改性二氧化锰振实密度达到了电解二氧化锰的要求，1 .79/Cm，以上，而且电化学性能与高锰酸钾（KMn04）氧化法制备的样品相似，10次累积放电容量明显高于EHD。x一射线衍射测定表明:制备出的MnoZ晶型为活性最高的y型。扫描电镜分析表明:如。2样品为球形细颗粒状。 在无汞可充碱锰电池电解液加入有机添加剂，通过析氢试验、短路试验、电化学性能测试等，研究电解液添加剂对电池性能的影响。试验结果表明:在电解液中加人0 .1%的TEA，缓蚀效率达到了73 .81%，抑制锌枝晶的生长，短路时间达到52 .8小时;电解液选用gmol/L KOH（zn。饱和）最为合适。同时研究了充放电制度对电池循环性的影响，发现先小电流恒流充电，再恒压充电，这样有利于电池的可逆性和容量的保持。 经过理论上的分析和探讨，掺杂后化学二氧化锰表现出良好的循环性能，其原因可能是由于:掺杂改变了二氧化锰的成分和结构，掺Bi改善了二氧化锰的晶体骨架结构的稳定性，使咖02具有“敞开”式结构，提高了H一的扩散能力以及抑制晶格膨胀的发生，避免Mn02转变为稳定、致密的结构，使二氧化锰在深度放电和浅度放电下都显示出良好的可充性。有机添加剂的作用可能是:它能通过吸附作用，在锌表面形成一层薄膜，阻止并减少。H一离子与HZO分子向锌粉表面接触，抑制锌的自腐蚀及枝晶生长。更多还原

【Abstract】 The preparation, modification and application of cathode active materials MnO2 were studied in this paper for developing mercury-free rechargeable manganese dioxide electrode material with practical prospects. These samples prepared by KMnO4 oxidation of MnCl2 solution and MnCO3 thermal decomposition were studied by chemical analysis , X-ray diffraction (XRD), scanning electron microscope(SEM), potential dynamic sweep, galcanostatic cycles method and other chemical methods in combination with modern spectrum techniques. The mechanism and disciplinarian of charge-discharge characteristic were also analyzed and discussed theoretically. The additives in electrolyte were primarily studied.The method of preparing chemical manganese dioxides by KMnO4 oxidation of MnCl2 salts in HNO3 solution had the merits of brief flow, low energy consume and simple technical condition. The optimum factors concluded from experiments were as following: reaction temperature was 85 C; reaction time was 1 hour; concentration of HNO3 was 0.5~1mol/L; manganese salt was MnCl2; dopant was Bi(NO)3; Mn:Bi was about 6~10. The experiment results showed that the accumulative capacities of 10 cycles of Bi-MnO2 were 300% higher than that of ordinary MnO2. XRD indicated that the samples mainly belonged to mixed crystal of -MOOH as the main phase. But the samples of KMnO4 oxidation had low density.The optimum factors concluded from experiments of MnCO3 thermal decomposition were as following: deposition temperature was 40 C ; deposition time were 1.5 hours; thermal temperature was 375C~390C; thermal time were 8 hours and so on. The tapped density of the MnO2 powder could be increased more than 1.7g/cm3 and therechargeability was also excellent. XRD indicated that the samples mainly belonged to crystal of -type structure. SEM indicated that the samples were the global granule microstrure.The effects of additives in electrolyte on the electrochemical performances of zinc electrode were investigated, through the hydrogen collection experiment, short circuit experiment and cyclic voltammetry method. The experiment results showed that the rechargeability of the alkaline zinc-manganese battery with 0.1% TEA in electrolyte was improved obviously and additives inhibited corrosion and dendrite of zinc electrode.Through the theoretical analysis and discussion, the reasons for excellent electrochemical behavior of modified MnO2 was like that the component and structure of modified MnO2 was changed, so that the MnO2 had a good rechargeability both in deep and shallow discharge regions.更多还原