Diffusion-Induced Transient Stresses in Li-Battery Electrodes Imaged by Electrochemical Quartz Crystal Microbalance with Dissipation Monitoring and Environmental Scanning Electron Microscopy

Abstract

Quick charging of Li-ion batteries is often accompanied by rapid expansion of composite battery electrodes, resulting in the appearance of transient stresses inside the electrodes' bulk. Although predicted theoretically, they have never been tracked by direct in situ measurements. Herein, using multiharmonic electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D), acoustic images of strong transient deformations in LiFePO 4 electrodes were obtained in the form of giant resonance frequency and resonance width shifts. The formation of cracks was verified by scanning electron microscopy. The effects of charging rate, stiffness of the polymeric binder, and solution concentration have been identified. The attractive feature of EQCM-D is its high sensitivity for selective probing of average mechanical characteristics of the operated electrodes, especially of the particle−binder interactions, directly linked to the electrode cycling performance. Using EQCM-D, an inexpensive, simple, and fast method of structural health monitoring for battery electrodes can be intelligently designed.

A practical guide to quartz crystal microbalance with dissipation monitoring of thin polymer films

“…75,76 These studies have been thoroughly reviewed elsewhere. 17,30,77 Here, we specifically focus on the application of EQCM-D to redox polymers, with special attention to the practicality of obtaining data of the highest quality.…”

“…The technique has also been widely used to analyze the formation, growth, and mechanical properties of solid electrolyte interphase (SEI) films under various conditions 75,76 . These studies have been thoroughly reviewed elsewhere 17,30,77 . Here, we specifically focus on the application of EQCM‐D to redox polymers, with special attention to the practicality of obtaining data of the highest quality.…”

Making Advanced Electrogravimetry as an Affordable Analytical Tool for Battery Interface Characterization

“…21,22 Innovative approaches combining EQCM-D with Online Electrochemical Mass Spectrometry (OEMS) have also being reported to grasp insights into the SEI formation mechanism on both model and practical electrodes. 23,24 Last, and of paramount importance has been the use of EQCM-D to understand the binder-particles 25,26 and solvent-binder 25,[27][28][29] interplays within the electrode as well. Altogether, these shows the span covered by EQCM-D to the battery field and exhaustive list can be found in references.…”

Towards the digitalisation of porous energy materials: evolution of digital approaches for microstructural design

“…Owing to the unique requirements of in situ and operando measurements, FIB-SEM was excluded from 4D imaging due to its intrinsic destructiveness, while the need for a vacuum and the sample damage prevent the utilisation of SEM and AFM. Environmental SEM has, however, been used in a 2D + 1 mode for the investigation of chemical distribution on surfaces, [75][76][77] such as crack and liquid water distribution 76 in electrodes. 77 Nondestructive X-ray CT and MRI have therefore been the main techniques for 4D imaging.…”