Lithium Isotope Effects upon Electrochemical Release from Lithium Manganese Oxide

Lithium was electrochemically released from lithium manganese oxide (LiMn2O4) to an electrolyte solution, a 1:2 v/v mixed solution of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) containing 1 M lithium perchlorate or sodium perchlorate (EC/EMC/LiClO4 or EC/EMC/NaClO4) to observe the lithium isotope effects that accompanied the lithium release. The lighter isotope of lithium, 6Li, was preferentially fractionated to the electrolyte solution phase, with the value of the lithium isotope separation factor ranging from 0.989 to 0.971 at 25 °C. The degree of the lithium isotope fractionation was slightly smaller in the LiMn2O4-EC/EMC/NaClO4 system than in the LiMn2O4-EC/EMC/LiClO4 system. The present systems are in great contrast with the lithium cobalt oxide (LiCoO2)-the electrolyte solution systems concerning the direction and magnitude of the lithium isotope effects, which seems mostly ascribable to the structural difference between LiMn2O4 and LiCoO2。