Electrochemical Behavior of Lithium in Alkaline Aqueous Electrolytes. I. Thermodynamics

Abstract

Detailed potential/pH stability diagrams for the lithium‐water system at 25°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. © 1999 The Electrochemical Society. All rights reserved.

Fundamental Understanding of Structural Reconstruction Behaviors in Oxygen Evolution Reaction Electrocatalysts

“…are in ionic form in a wide range of pH values and potentials, especially under anodic conditions over 1.23 V versus reversible hydrogen electrode (RHE), which indicates their facile leaching properties during OER process. [23,[49][50][51] However, the realistic conditions for cation leaching would be quite compli-cated due to their surrounding environments, i.e., coordination structure, applied potentials etc. To date, the mechanisms underlying metal leaching during OER remain elusive.…”

Electrochemical Impedance Spectroscopic Study of Passive Zirconium

“…The PDM is an atomic scale model that describes the oxidation of passive metals in aqueous media, in terms of the generation and annihilation of point defects at the interfaces of the barrier layer of the passive film. 11,13 The model assumes that, depending on the chemistry of the coolant and the prevailing electrochemical conditions, the barrier layer is a highly defective oxide or hydride, whose principal point defects are cation vacancies, anion vacancies, and metal interstitials, and concludes that the barrier layer must grow into the metal via the generation of hydrogen vacancies ͑in the case of a hydride barrier layer͒ or oxygen vacancies ͑for an oxide barrier layer͒ at the metal/barrier layer interface ͑MBI͒. On the other hand, the porous outer layer is envisioned to form via the hydrolysis and precipitation of zirconium cations derived from the barrier layer, either via dissolution of the barrier layer matrix at the barrier layer/ outer layer interface ͑BOI͒ or from cations that are transmitted through the barrier layer via cation vacancies on the cation sublattice or as cation interstitials.…”

“…In this system, the passive film is postulated to comprise a nonporous, defective hydride barrier layer ͑ZrH 2−x ͒ and a precipitated, porous oxide outer layer. Impedance models for the barrier layer, based on the PDM, have been extensively developed, 11,[13][14][15][16][17][18][19] but, to our knowledge, only the work of Pensado et al 13,14 for lithium in concentrated hydroxide solution and Part I of the present series on zirconium 20 has previously attempted an optimization of a bi-layer impedance model on EIS data. In the work of Pensado et al, 13,14 the variables in the model were "lumped parameters" and values for many of the individual model parameters could not be obtained.…”

“…Impedance models for the barrier layer, based on the PDM, have been extensively developed, 11,[13][14][15][16][17][18][19] but, to our knowledge, only the work of Pensado et al 13,14 for lithium in concentrated hydroxide solution and Part I of the present series on zirconium 20 has previously attempted an optimization of a bi-layer impedance model on EIS data. In the work of Pensado et al, 13,14 the variables in the model were "lumped parameters" and values for many of the individual model parameters could not be obtained. In the present work, we have employed a different method of formulating the model and, using an unconstrained optimization procedure, we have extracted values for the individual parameters in the PDM bi-layer model that are physically eminently reasonable.…”

The Pivotal Role of s‐, p‐, and f‐Block Metals in Water Electrolysis: Status Quo and Perspectives

“…Compared to this, alkali metal Li species is prone to be converted to the Li + during both OER and HER through the whole pH range. [ 269 ] As for the Ba‐water system, BaOH + can be formed during OER in alkaline media; while Ba 2+ is the dominated species during OER in acidic media and HER in alkaline and acidic media. [ 270 ] Theoretically, copresence of metal hydroxide and oxide for rare earth metal Ce can be observed during OER in alkaline media while only the metal hydroxide was formed during the acidic media.…”