Session: 11-05-01: Thermophysical Properties: Characterization and Modeling Across Scales

Paper Number: 150522

150522 - Thermal Wave Sensing for Operando Mapping of Subsurface Electrochemical, Mechanical, and Thermal Transport Properties 

Measuring real time material properties such as ion concentration gradients or microcrack propagation without disrupting the system being measured typically requires significant infrastructure such as synchrotrons or neutron beams. In this talk, I will discuss Thermal Wave Sensing (TWS) as an emerging electrothermal frequency domain technique for the non-invasive operando measurement of a variety of subsurface material properties. Using minor surface temperature perturbations, TWS allows for probing of opaque, multi-layered systems during cycling. Unlike optical techniques that require high-energy x-rays to penetrate such systems, relatively small heat pulses readily permeate any interconnected system. I will describe the operating principle behind this technique and present an example of its application to representative next-generation 3D-architected battery electrodes. This electrochemical system is important for the quest to optimize the balance between power density and energy density, which has led many researchers to explore new battery chemistries and geometries. However, the increasing complexity of these systems presents significant challenges in experimental validation, particularly in non-invasively measuring the subsurface properties of electrochemically active, optically opaque systems during operation, making it an ideal candidate for TWS.

 

At its core, TWS measures the thermal transport properties of a sample as a function of subsurface spatial location. This information is extracted from surface-only measurements of the change in temperature phase and amplitude resulting from diffusive thermal waves sent into the sample. By sweeping over a range of frequencies, the technique characterizes the thermal transfer function of the system, which depends in turn on its internal geometry and thermal transport properties. These thermal properties can then be correlated with any non-thermal property that influences thermal transport. However, due to the sensitivity of TWS to a wide array of properties, careful modeling and calibration are required to discern which changes to the measured thermal signal are attributable to changes in the non-thermal property of interest. I will review the physical mechanisms governing the relationship between thermal property changes and select non-thermal properties of interest, with a focus on diffusive lithium-ion transport and lattice disruption as relevant to electrochemical cells. I will also discuss how TWS has the potential to detect morphological and chemical defects caused by cycling, such as pulverization, cracking, interfacial separation, lithium plating, and dendritic growth. This novel sensing approach can support development of intelligent, more efficient battery designs in the future, and is adaptable to other energy storage systems such as fuel cells and thermal energy storage materials.

Presenting Author: Aaron Khan Boston University

Presenting Author Biography: Aaron Khan is a PhD Candidate in the Division of Materials Science & Engineering at Boston University. He is developing and utilizing thermal sensing techniques to probe novel materials in the sustainability sphere. His interests include thermal energy storage, carbon capture, and phonon transport.

Authors:

Aaron Khan Boston University
Anton Resing Boston University
Joerg Werner Boston University
Sean Lubner Boston University