Lithium isotope effects accompanying oxidation reactions in lithium ion secondary batteries

在从锂钴氧化物（LiCoO2）阴极向含有锂离子的碳酸乙烯酯基有机电解质溶液的电化学锂释放中，观察到较重的同位素7Li优先转移到电解质溶液。与此相反，当电解质溶液不含锂离子时，没有观察到锂同位素效应。结果表明，电解质溶液的种类控制着锂离子电池正极与电解质溶液之间锂同位素交换平衡的实现，当锂锰氧化物（LiMn2O4）用作正极材料时，较轻的锂同位素6Li优先释放到电解质相中，而与电解质溶液的种类无关。LiCoO_2和LiMn_2O_4正极材料在锂同位素效应方面的巨大差异可能主要归因于两种正极材料的结构差异。

In the electrochemical lithium release from a lithium cobalt oxide (LiCoO2) cathode to ethylene carbonate-based organic electrolyte solution containing lithium ions, it was observed that the heavier isotope, 7Li, was preferentially transferred to the electrolyte solution. Contrary to this, no lithium isotope effects were observed when the electrolyte solution contained no lithium ions. It was induced that the kind of electrolyte solution controlled the attainment of the lithium isotope exchange equilibrium between the cathode and the electrolyte solution.When lithium manganese oxide (LiMn2O4) was used as the cathode material, the lighter isotope of lithium, 6Li, was preferentially released to the electrolyte phase, irrespective of the kind of electrolyte solution. The great contrast in lithium isotope effects between LiCoO2 and LiMn2O4 cathodes seemed mostly ascribable to the structural difference between the two cathode materials.