【作者】 侯宏英；

【导师】 杨长春；

【作者基本信息】 郑州大学 ， 物理化学， 2002， 硕士

【摘要】 本论文对以难溶高铁酸盐K₂FeO₄为正极活性物质的水溶液碱性高铁电池进行了较为系统的研究。采用组装实验电池、X-射线衍射（XRD）和循环伏安（CV）的方法，从实验电池的放电特性、充放电循环特性、自放电特性，不同高铁酸盐的结构特性和电化学特性几个方面，对4种金属负极材料（Al、Fe、Zn、Cd）、6种隔膜材料（复合玻璃纤维、幅射接枝聚乙烯、改性聚丙烯、聚氯乙烯、维尼纶无纺布、皂化再生纤维素）、4种集流体材料（泡沫镍、以铁网为加强层的泡沫镍、切拉银网、炭纤维编织网）在碱性高铁电池中的适用性进行了比较研究；对2种杂质组分（ZnO、Fe（OH）₃）和2类不同贮存方式（干、湿）对实验电池自放电特性的影响进行了比较研究；对3种方法（高温固相反应、次氯酸盐氧化、直流电解）所制K₂FeO₄的实验电池的放电特性、结构特性和电化学性能进行了比较研究。结果表明： 一、不同金属负极与K₂FeO₄所组装实验电池的开路电压、恒阻放电曲线中的平台工作电压、恒阻放电截止到1.0V时K₂FeO₄的容量利用率依Al／K₂FeO₄、Zn／K₂FeO₄、Cd／K₂FeO₄、Fe／K₂FeO₄的顺序逐渐降低；可充电循环性依Cd／K₂FeO₄、Fe／K₂FeO₄Zn／K₂FeO₄的顺序逐渐变差；虽然在水溶液电液中Al／K₂FeO₄体系不可能作为二次电池使用，但从其放电容量、放电功率等方面看该体系作为大功率高容量一次电池或贮备电池具有很大的潜力。 二、 高分子隔膜材料具有或强或弱的还原性，在实验电池中与高铁电池的正极直接接触，可能会被高铁酸盐氧化，造成电池正极容量衰减及稳定性下降。从观察等面积的隔膜引起同浓度同体积的Na₂FeO₄溶液的分解实验可知，不同隔膜材料引起Na₂FeO₄溶液分解速率从大到小的顺序是，皂化再生纤维素膜＞维尼纶无纺布＞改性聚丙烯膜＞聚氯乙烯膜＝辐射接枝聚乙烯膜＞复合玻璃纤维毡。作为隔膜用于Zn／K₂FeO₄实验电池，正极活性物质K₂FeO₄的放电容量效率分别为复合玻璃纤维膜93％、辐射接枝聚乙烯膜68％、改性聚丙烯微孔膜56％、聚氯乙烯微孔膜47％、维尼纶无纺布38％、皂化再生纤维素膜24％。虽然前五种隔膜的还原性很小或较小，作为与高铁酸盐直接接触的隔膜表现出较好的适用性，但随着与电液接触时间的增长，隔膜的孔隙容易浸水，从而导致高铁电池正极活性物质K₂FeO₄的分解，这一点使这几种隔膜不能用于贮备高铁电池。辐射接枝聚乙烯微孔膜和改性聚丙烯微孔膜的抗氧化性较强。皂化再生纤维素膜能有效地阻止溶解态高铁酸盐向负极的渗透，及负极可溶性放电产物向高铁酸盐正极的渗透。 三、以碳纤维编织布、泡沫镍、切拉银网，作为实验电池的正极集流体，从K₂FeO₄的放电容量效率看，碳纤维编织布优于泡沫镍；以铁编织网为加强层的复合结构泡沫镍基体，对保证Fe／K₂FeO₄体系的正常放电有利，对Zn／K₂FeO₄体系其性能并无明显的优点；在Al／K₂FeO₄和Zn／K₂FeO₄两种电池体系中切拉银网与泡沫镍无明显差异。从避免微量金属影响高铁酸盐的稳定性考虑，碳纤维编织布应是较其它金属集流体更适合于高铁电池，但也造成高铁正极的压制成型、极耳的引出，及其与壳体间的联接变得困难。 四、正极中K₂FeO₄的分解是引起实验电池自放电的主要表现形式，所以对K₂FeO₄的分解有影响的诸多因素都会影响自放电。（1）压制成型的正极经过相同的存放时间，不与电液接触情况下K₂FeO₄的分解比例，比与电液接触情况的小。（2）压制成型的正极与金属负极组装成实验电池后再存放情况下，较正极单独存放情况下K₂FeO₄的分解比例高。（3）在正极活性物质中含有ZnO或Fe（OH）₃杂质时的自放电率高于仅在KOH电液中含有这些杂质。且Fe（OH）₃对自放电的影响程度大于ZnO。（4）以浓度较高的KOH溶液作为电液有利减缓正极中K₂FeO₄的分解。依据这些研究结果，本文认为引起高铁正极自 以高铁酸盐为正极活性物质的碱性高铁电池研究 放电的因素有还原性物质的存在、金属负极自放电过程所析出的氢气、固体K。FeO。的溶 解一分解一再溶解一再分解及负极放电产物和正极放电产物对这一过程的催化促进作 用。 五、粉末XRD结果表明，不同方法所制KZFeO。的纯度从低到高的顺序是高温固相 反应法、次氯酸盐氧化法、直流电解法。K。FeO。正极的容量利用率及自放电率与其纯度 密切相关。所以直流电解法是制备电池级KZFOO4较为理想的方法。 六、将电池级固体KZFZO4与胶状石墨的混合物涂覆于玻炭电极、或填充于泡沫镍基 体上，在0—0．SV（VS丑旮H叨）电位范围内进行循环伏安电扫描，所得循环伏安特性虽然 显示KZFCO4具有一定的可充放电循环性，从CV曲线上具有明显的阴极电流峰和阳极 电流峰循环次数可达300—600周。但与FeO。‘“的生成和还原相应的阳极电流峰和阴极电 流峰的峰电位范围分别是 0石5－0．75V和0．15－0．20V（vs．HgMgO），两者相差 400—450mV， 这表明在所采用的条件?更多还原

【Abstract】 In this thesis, the uper-iron alkaline batteries .utilizing insoluble ferrate（VI）-K₂FeO₄ as cathode active material, was more systematically investigated by the mothods of EB, XRD, and CV. The fitness of four negative electrode materials such as Al, Fe, Zn, Cd ,and of six membranes materials: microfiber glass mat separator, polyethylene, polypropylene, polyvinyl chloride, vinylon, soapnated cellulose acetate ,and of four current collects: carbon fiber; nickel foam; nickel foam sthongthened by iron wire net, punched silver grid in the super-iron alkaline batteries was comparatively studied. The influence of two storaged method （with and without electrolyte） and two impurities （ZnO,Fe（OH）3） to the experiment cell’s self-discharge nature was also comparatively studied .At last , the nature of discharge .structure and electrochemistry of experimental cell with K2FeO4 as cathode active material prepared by three different methods: high temperature reaction ,hypochlorite oxidizing and electrolysis, was comparatively studied .We can conclude:i) The open-circuit potential and the flat of work potential and the percent of capacity of K2FeO4 till 1.0V during the discharge at constant load of experimental cells decreased by the order of Al/K2FeO4, Zn/K2FeO4, Cd/K2FeO4 ,Fe/K2FeO4. As for the nature of charge-discharge cycle, Cd/K2FeO4 Fe/K2FeO4 Zn/K2FeO4.In water solute electrolyte , although Al/K2FeO4 cann’t be used as storage battery ,it have great potential as primary cell or storage cell from the aspect of its discharge capacity .discharge power.ii)The membrane materials of polymer may be oxidized by ferrate（VI）because of their strong or weak reductivity ,when they were directly connect with the ferrate（VI） cathode in experiment cell., so the the cathode’s capacity decreased. According to the observed experiments that the Na2FeO4 solution with the same concentration and volume were decomposed by the same area of different membrane ,we learned the order of the decomposing rate of Na2FeO4 caused by different membranes: soapnated cellulose acetate > vinylon > polypropylene polyvinyl chloride = polyethylene microfiber glass mat. When they were respectively used as separator in Zn/K2FeO4 battery, the percent of capacity of the cathode active material Na2FeO4 were : microfiber glass mat’s:93%; polyethylene’s:68%; polypropylene’s:56%;polyvinyl chloride’s:47%; vinylon’s:38%; soapnated cellulose acetate’s:24%.Although Five of them （not concluding soapnated cellulose acetate） had very weak or weaker reductivity as separator in super-iron battery ,for which they were more suitable to being separator in super-iron battery . but they were easy to be soaked by water for being connect with KOH solution for long time , which led to cathode active material’s decomposition ,thus they cann’t be fit for being separator in super-iron battery . Polyvinyl chloride and polyvinyl chloride can resist to be oxidized . Soapnated cellulose acetate can prevent dissolved ferrate（VI） penetrating toward the anode and prevent dissolved cathode’s discharge products penetrating toward the cathode.iii) With carbon fiber, nickel foam, nickel foam sthongthened by iron wire net .punched silver grid as cathode current collectors .form the percent of capacity of K2FeO4, carbon fiber was better than nickel foam, and the nickel foam sthongthened by iron wire net wasadvantaged to normal discharge of Fe/K2FeO4 ,but the Zn/K2FeO4 hadn’t apparent virtue. As for Al/K2FeO4 and Zn/K2FeO4, nickel foam and punched silver grid had no apparent difference. In order to avoid the influence of trace metal to the stability of ferrate（VI） , carbon fiber was more suitable, but it led to the problem of being prepared of the cathode ,of emerging of the electrode’s ear and of connecting between the base and shell.iv)The decomposition of K2FeO4 in the cathode was the main behaving pattern of the experimental cell’s self-discharge, so many factors having influence to the decomposition of K2FeO4 can effect the self-discharge . （l）The fraction of the decompositio更多还原