Operando Thermal Wave Sensing of Lithium Dynamics in Architected Battery Electrodes

The quest for optimizing the balance between power density and energy density 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. To address this challenge, we are employing thermal wave sensors (TWS) on representative next-generation 3D architected battery electrodes. Using minor surface temperature perturbations, TWS allow for virtual 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.<br/><br/>At its core, TWS measure the thermal transport properties of a sample with spatial resolution. These properties can be correlated with any of numerous factors that influence thermal transport. However, due to the sensitivity of TWS to a wide array of properties, careful modeling and calibration are required to discern which observed effects are attributable to changes in the property of interest. Applying TWS to 3D batteries, we aim to model and validate lithium transport through low-tortuosity, interdigitated electrodes. TWS also have 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 novel, more efficient battery designs in the future, and is adaptable to other energy storage systems such as fuel cells and thermal energy storage materials.