ROLE OF TERNARY PHASES IN CATHODE REACTIONS
ROLE OF TERNARY PHASES IN CATHODE REACTIONS
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DOI：
10.1149/1.2132817
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发表时间：
1976-01-01
影响因子：
3.9
通讯作者：
WHITTINGHAM, MS
中科院分区：
文献类型：
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作者：
WHITTINGHAM, MS
已经发现锂与几种过渡金属氧化物和硫化物之间的电池反应产生三元相，而不是如先前提出的锂氧化物或硫化物的形成。这些反应在25 ° C下发生，基本上保留了晶格，从而促进了二次阴极行为。据发现，电池的可逆性优化时，没有化学键被打破放电过程中，也就是说，在三元相形成的插层反应，其中存在广泛的非化学计量的系统Li/TiS 2。对于V2 O 5和TiS 3，在一些化学键断裂的情况下，发现部分或困难的可逆性，但是当所有的键断裂时，例如在CuS中，电池仅表现出主要特性。关于这类材料的阴极还原机理，甚至反应产物的机理，人们知之甚少。因此，观察到的电动势与简单还原反应的计算结果往往没有什么关系。对于V2 O 5还原为VO 2，预计电动势为2.4 V（1），但观察到的电池电动势为3.5 V（2，3），对于（CF），进入石墨和LiF，自由能变化对应于4.6 V，但实验观察到的仅为2.8 V（4，5），对于MoO 3，得到MoO 2和Li 2S，其值为2.2（1）和2.8 V（2，6）。在硫化铜的情况下，电池电动势是预期的Li 2S和Cu的形成，2.3 V（7），在许多情况下，卤化物没有差异。在低温下，固态的反应倾向于通过最简单的途径进行，也就是说，通过涉及最小结构变化的途径。因此，在室温下用氢还原三氧化钨时，氢被引入到晶格中，而没有任何显著的结构变化，得到氢钨青铜，H~ WO 3（8）。在高于青铜稳定极限~ 350 ℃的温度下，通过沿沿着离散面抽取氧并形成一定间隔（9，10）的剪切面而发生还原。剩下的水晶-
The cell reactions between lithium and several transition metal oxides and sulfides have been found to produce ternary phases and not the formation of lithium oxide or sulfide as previously proposed. These reactions, at 25~ take place with essential retention of the crystalline lattice, thus facilitating secondary cathodic behavior. It is found that cell reversibility is optimized when no chemical bonds are broken during discharge, that is, where ternary phases are formed by an intercalation reaction and where a broad range of nonstoichiometry exists as in the system Li/TiS2. Where some chemical bonds are broken as for V205 and TiS3 partial or difficult reversibility is found, but when all the bonds are broken as for example in CuS, the cell only exhibits primary characteristics.There has been much recent work in ambient temperature batteries using lithium anodes and cathodes comprising metallic compounds of the halides, oxides, and chalcogenides. Very little is known concerning the mechanism of cathodic reduction of such materials or even of the products of reaction. Thus frequently the observed emf's bear little, if any, relation to those calculated for simple reduction reactions. For V205 reduction to VO2, an emf of 2.4 V is expected (1) but the observed cell emf is 3.5 V (2, 3), for (CF), going to graphite and LiF the free energy change corresponds to 4.6 V and yet only 2.8 V is observed experimentally (4, 5), and for MoO3 giving MoO2 and Li2S the values are 2.2 (1) and 2.8 V (2, 6). In the case of cupric sulfide the cell emf is that expected for the formation of Li2S and Cu, 2.3 V (7), and in many cases there is no discrepancy for the halides. At low temperatures reactions in the solid state tend to go by the easiest route, that is, by the one involving minimal structural change. Thus in the reduction of tungsten trioxide by hydrogen at ambient temperatures hydrogen is incorporated into the lattice without any significant structural changes giving a hydrogen tungsten bronze, H~ WO3 (8). At temperatures,~ 350~ above the stability limit of the bronze, reduction occurs by abstraction of oxygen along discrete planes with the formation of shear planes at definite intervals (9, 1O). The remainder of the crystal-