Rechargeability of MnO2 in KOH Media Produced by Decomposition of Dissolved KMnO4 and Bi ( NO 3 ) 3 Mixtures II. A Reaction Viewpoint on the Role of Bi
Rechargeability of MnO2 in KOH Media Produced by Decomposition of Dissolved KMnO4 and Bi ( NO 3 ) 3 Mixtures II. A Reaction Viewpoint on the Role of Bi
复制标题
溶解的 KMnO4 和 Bi (NO 3 ) 3 混合物分解产生的 KOH 介质中 MnO2 的可充电性 II。
DOI：
10.1149/1.1837492
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发表时间：
1997
影响因子：
3.9
通讯作者：
L. Yu
中科院分区：
文献类型：
--
作者：
L. Yu
Bi原子的存在对MnO2的可充电性的有益影响可以通过反应观点来解释。Bi（III）和Mn（X）原子（X = IV、III或II）产生稳定的配合物。此外，Mn 3 O 4的形成可以看作是一个逐步的三维聚合过程，即，作为由碱性加成反应组成的反应链。通过这种方式，我们可以很容易地理解Bi（III）的存在干扰了聚合过程，因为这些络合物形成反应使加成反应短路。当Bi原子取代Mn（II）或Mn（III）原子时，尖晶石晶格的构建受到干扰。由于Bi（III）离子的尺寸（0.96 A）比Mn（II）（0.67 A）或Mn（III）（0.73 A）离子大得多，它们不能将自己插入尖晶石晶格中。这防止了广泛的尖晶石晶格的形成，众所周知尖晶石晶格是差的电活性化合物。反应的观点使我们能够定义两个标准，以寻找对MnO2材料的可再充电性的有益影响：（i）金属阳离子和Mn原子之间的强相互作用是必需的，（ii）阳离子的半径必须足够大，以防止其插入尖晶石晶格。
The beneficial effect of the presence of Bi atoms on the rechargeability of MnO 2 can be explained through a reaction viewpoint. Bi(III) and Mn(X) atoms (X = IV, III, or II) give stable complexes. Furthermore, the formation of Mn 3 O 4 can be viewed as a stepwise 3D polymerization, i.e., as a reaction chain composed of basic addition reactions. In this way, we can easily understand that the presence of Bi(III) disturbs the polymerization progress, because these complex-formation reactions short-circuit the addition reactions. When a Bi atom replaces a Mn(II) or Mn(III) atom, the building of spinel lattice is disturbed. As the size of Bi(III) ions (0.96 A) are much larger than Mn(II) (0.67 A) or Mn(III) (0.73 A) ions, they cannot insert themselves into the spinel lattice. This prevents the formation of an extensive spinel lattice, which is well known to be a poor electroactive compound. The reaction viewpoint allows us to define two criteria for searching a beneficial effect on the rechargeability of MnO 2 material: (i) a strong interaction between the metal cations and Mn atoms is required, (ii) the radius of the cation must be sufficiently large to prevent its insertion into the spinel lattice.