【作者】 张春霞；

【导师】 夏熙；

【作者基本信息】 新疆大学 ， 物理化学， 2001， 硕士

【摘要】 可充碱锰电池以其价格便宜，容量大，贮存性能良好等优点受到普遍关注，但其循环寿命低．由于稀土元素可以作为贮氢电极的材料，且我国的稀土资源丰富，因此考虑以MH电极代替碱锰电池中的Zn电极，以提高其性能．在这方面己经进行的工作证实其是可行的．但MH／MnO₂电池存在一个问题，即MH与MnO₂的充放电态不匹配．因此，我们制备了一些化合价低于4 的锰氧化物，以期其能与MH 组成电池，以解决充放电态不匹配的问题．本文的主要工作： 1)在水相和有机相中分别用搅拌和超声等不同条件下，对 1．C．No1EMD进行部分还原．并对还原产物进行了XRD，TEM，红外光谱等测试以及氧化度测定，结果表明，超声在水相还原中具有加快反应速度、引起产物晶型改变的作用． 2)对还原产物进行了充放电，循环伏安，扩散系数的测定等电化学性能研究，结果表明：部分还原样以及掺了Ni（OH）₂的部分还原样作为电极活性材料，其累积放电容量均高于普通的1．C．No1EMD及其掺Ni（OH）₂的累积放电容量．在每一周充放后的质子扩散系数的测定结果证实了采用部分还原样以及掺Ni（OH）₂的样品电极在充放过程中，质子扩散系数并不减小，电极的可逆性提高，同时也证实了Ni（OH）₂在电极的放电区间内能有效抑制Mn₃O₄的形成． 3)在氮气保护下，对固相合成的 MnC₂O₄及掺杂的 MnC₂O₄和MnCO₃进行热分解，以期得到MnO 和改性的MnO．对样品进行了热重／差热，XRD，TEM，溶解度等测定，证明产物确为MnO．由固相合成的产物作为前驱体热分解得到的样品粒径均匀，团聚较小．溶解度的测定结果表明MnO在KOH中的溶解度随碱液浓度的增大而增大． I 4 4)对热分解产物进行了充放电，循环伏安，恒电流极化，Tafe］曲线分析，交流阻抗分析，得出未掺杂的MnO直接作为电极活性材料，其电化学活性很差，但通过掺BI，Ph进行改性，提高了其可充性，＊1 的影响主要在于第二电子放电，Ph则可以延长第一电于放电．通过动力学的研究发现，在掺Bi的MnO在充电过程，电化学极化为主要的控制步骤．更多还原

【Abstract】 Alkaline manganese rechargeable batteries are. attractive because of their low cost, high capacity and long shelf life. However, they have the disadvantage of short cycle-life. On the other hand, there is abundant of rare earth in our country that can be used as storing hydrogen materials. Therefore, it is considered that Zn anode is replaced by MH electrode in alkaline manganese battery to improve its performance. Some work have been done and testified its feasibility. However, the main obstacle of investigation of MH/MnO2 batteries is the mismatched states of discharge and charge of cathode and anode, i.e. MnO2 is in the state of charge, while MH is in the state of discharge. Therefore, some manganese oxides were prepared that the valence of manganese is lower than four. It is expected that the obstacle of mismatched state could be overcome by assembling these manganese oxides used as cathode with MH electrode.The following items have been done:1) I.C.No 1 HMD were partly reduced under different conditions, such as stirring in aqueous and organic environment and ultrasound in aqueous and organic environment respectively. The reduced samples were characterized by oxidation degree analysis, X-ray diffraction, IR spectrum and TEM technique. Some conclusions can be drawn that in aqueous reduction, ultrasound can accelerate the reduction and plays a role as catalyst to change the crystallgraphic form of products.2) The electrochemical performance of reduced samples was studied by constant-current charge-discharge, cyclic-voltammetry and potentiastaticpulse technique. The accumulative discharge capacity of partly reduced samples and these samples added proper amount of nickel hydroxide are lager than the capacity of I.C.NolEMD added nickel hydroxide. The results of measuring H+ diffusion coefficient of each charge-discharge cycle show that the coefficient of the sample electrode and the sample electrode added Ni(OH)2 do not decrease with the cycles. Therefore, the reversibility of electrode is improved. Meanwhile, it is confirmed that Ni(OH)2 can reduce the formation of inactive Mn3O4.3) MnO and modified MnO were prepared under nitrogen atmosphere by thermally decomposition of MnC2O4 and doped MnC2O4 and MnCO3 synthesized by solid-state reaction respectively. Samples were characterized by TG/DTA, X-ray diffraction, TEM and measurement of solubility. The particle size of sample is well distributed and the cluster decreases. The solubility of MnO in KOH increases with the concentration of KOH.4) The samples were studied by galvanistatic charge-discharge, cyclic-voltammetry, constant current polarization. The results show that MnO which not be modified can not be use as electrode active materials because of its poor electrochemical activity. Meanwhile, the rechargeabilify of MnO modified by Bi and Pb is improved. Bismuth could prolong the second electron equivalent discharge and Lead could improve the first electron equivalent discharge performance. It is concluded by kinetic study that the electrochemical polarization is the controlled step in the charge process of MnO doped with Bismuth.更多还原