Transverse and Longitudinal Degradations in Ceramic Solid Electrolytes

Abstract

Ceramic solid electrolytes conducting primarily a specific ion but with minuscule electron leakage are used in many electrochemical devices. Their degradation phenomena may be classified into two broad categoriesa slow transverse mode accumulating damage normal to the ionic current direction and a fast longitudinal mode accumulating degradation parallel to the current direction. Examples of the transverse mode include oxygen bubbles on transverse grain boundaries, in-plane electrolyte cracking in solid oxide electrolysis cells, and cathodic reduction of beta-alumina electrolytes in Na−S batteries. Examples of the longitudinal mode include short-circuiting dendrite formation in metal batteries of both the Na−S type and the all-solid-state lithium metal type. Analogous instability modes are also seen in fieldassisted ceramic processing, dielectric devices, and memristors. These phenomenological similarities across different devices, operating conditions, and technologies, as well as the origins of their damage mechanisms, can be understood in terms of the highly nonlinear spatial distributions of the minority carriers (electron/hole) and the chemical potential of the equivalent charge-neutral species such as O 2 ; such distributions can in turn cause or exacerbate damaging concentrations of stress and electric fields. This review also outlines strategies for improving material designs to mitigate degradation, which will be especially important for operations and applications under extreme electrochemical conditions.

A Review of Polymer‐based Solid‐State Electrolytes for Lithium‐Metal Batteries: Structure, Kinetic, Interface Stability, and Application

“…Active fillers are the main conductive medium, and polymers act as a binder for cross‐linking and adhesion. It forms three different ion transport paths in the composite electrolytes [100,101] . Specifically, there are three‐phase conduction mechanisms in the inorganic‐organic composite SSE, including active filler conduction, polymer/filler interface conduction, and polymer (lithium salt) conduction [102] .…”

“…It forms three different ion transport paths in the composite electrolytes. [100,101] Specifically, there are three-phase conduction mechanisms in the inorganic-organic composite SSE, including active filler conduction, polymer/filler interface conduction, and polymer (lithium salt) conduction. [102] Therefore, more work focused on improving the ionic conductivity of polymer-based SSEs by incorporating active fillers.…”

Oxide Cathodes: Functions, Instabilities, Self Healing, and Degradation Mitigations

“…Lastly, it is important to acknowledge the spatial heterogeneity both at the cathode particle level and at the composite electrode level. − The heterogeneity depends on many factors such as the spatial distributions of active materials, conductive carbon, binder, and porosity, macroscopic defects in the electrode, the shape and crystallography of cathode particles, and the spatial uniformity of the surface passivation. It affects the transport of Li + and electrons, as well as the local chemical potential of Li 0 . − With a large spatial heterogeneity either from cathode processing or after extended cycling, such as detachment of some particles from the electron percolating network or even wholesale detachment of the electrode from the current collector, these particles would be electrically insulated and become electrochemically inactive. What is worse, the charge/discharge current density calculated from the nominal active material loading would only be loaded on the active ones, which is equivalent to a high-rate cycling condition and result in accelerated degradations.…”

Carbothermal Shock Synthesis of High Entropy Oxide Catalysts: Dynamic Structural and Chemical Reconstruction Boosting the Catalytic Activity and Stability toward Oxygen Evolution Reaction

“…Recent research showed that electrocatalysts designed by alloying two or more elements (e.g., transition metals, TM) showed promising enhancement in catalytic activity and durability due to synergistic effects from alloying, such as strain engineering or valence electron exchange. [4,[10][11][12][13][14][15] Nevertheless, the full potential of the alloying approach is still constrained by standard synthesis methods (e.g., wet chemistry and thermal decomposition techniques) due to the thermodynamics rules (e.g., miscibility of the different alloying elements, Mixed transition-metals (TM) based catalysts have shown huge promise for water splitting. Conventional synthesis of nanomaterials is strongly constrained by room-temperature equilibria and Ostwald ripening.…”