Electrochemical behavior of lithium in alkaline aqueous electrolytes - I. Thermodynamics

Detailed potential/pH stability diagrams for the lithium-water system at 25 degrees C have been derived as part of a program to describe the electrochemistry of the lithium anode in aqueous alkaline environments. The diagrams include lithium hydride as a stable solid phase at sufficiently negative potentials, and it is postulated that the passive film on Li in contact with concentrated alkaline solutions, under open-circuit conditions, comprises a LiH barrier layer covered with a hydrated LiOH outer layer. The postulated existence of Li2O as a barrier layer, under open-circuit conditions, is inconsistent with the thermodynamic data for metallic lithium in contact with concentrated LiOH and LiOH + KOH solutions. (C) 1999 The Electrochemical Society. S0013-4651(98)05-080-0. All rights reserved.