Linking Void and Interphase Evolution to Electrochemistry in Solid-State Batteries Using Operando X-Ray Tomography

Abstract

<p>Despite progress in solid-state battery engineering, our understanding of the chemo-mechanical phenomena that govern electrochemical behavior and stability at solid-solid interfaces remains limited compared to solid-liquid interfaces. Here, we use <i>operando</i> synchrotron X-ray computed microtomography to investigate the evolution of lithium/solid-state electrolyte interfaces during battery cycling, revealing how the complex interplay between void formation, interphase growth, and volumetric changes determines cell behavior. Void formation during lithium stripping is directly visualized in symmetric cells, and the loss of contact at the interface between lithium and the solid-state electrolyte (Li<sub>10</sub>SnP<sub>2</sub>S<sub>12</sub>) is found to be the primary cause of cell failure. Reductive interphase formation within the solid-state electrolyte is simultaneously observed, and image segmentation reveals that the interphase is redox-active upon charge. At the cell level, we postulate that global volume changes and loss of stack pressure occur due to partial molar volume mismatches at either electrode. These results provide new insight into how chemo-mechanical phenomena can impact cell performance, which is necessary to understand for the development of solid-state batteries.</p>

Role of Areal Capacity in Determining Short Circuiting of Sulfide-Based Solid-State Batteries

“…Recent studies have also demonstrated that stripping at Li/SSE interfaces plays a major role in destabilizing subsequent lithium deposition [25][26][27][28][29] . Stripping current densities that exceed the rate at which lithium can be replenished at the interface via deformation and/or self-diffusion lead to contact loss through the formation of interfacial voids.…”

“…Stripping current densities that exceed the rate at which lithium can be replenished at the interface via deformation and/or self-diffusion lead to contact loss through the formation of interfacial voids. Contact loss causes higher current densities at the interface, and current constriction at the edges of interfacial voids further increases local current densities 10,25 . When plating occurs after contact loss, these higher local current densities increase the likelihood that lithium will penetrate through the SSE to form a short circuit.…”

Visualizing reaction fronts and transport limitations in solid-state Li-S batteries via operando neutron imaging

“…14 Notably, progress in the field of X-ray imaging allowed for the elucidation of solid-state batteries while under operation. [15][16][17][18] However, the identification of lithium is challenging.…”

Polymorphism of Garnet Solid Electrolytes and Its Implications on Grain Level Chemo-Mechanics

“…However, intrinsic thermodynamic, electrochemical and mechanical instability between the components of the SSB significantly limits their performance 4 . These unfavorable electro-chemo-mechanical behavior at the numerous solid | solid interfaces within the SSB leads to non-optimal material utilization, mechanical degradation, and poor ion transport 1,5,6,7,8,9,10,11 . These phenomena transcend several orders of magnitude in timeand length-scales and are yet to be fully understood.…”