High Resolution 4D In-Operando Imaging of High Energy Density Battery Electrode Cycling

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

This research addresses the challenges faced with advanced anodes for next generation lithium batteries for transportation applications, using a combination of advanced imaging and diagnostics. The research will establish and utilize an ultra-high spatial and temporal resolution test bed for 4D (3D space + time) in-operando imaging of batteries using nano-scale X-ray computed tomography (nano-CT). The scientific objective is to elucidate the failure mechanisms of the most promising anode chemistries for electric and hybrid vehicles, including Li metal, tin (Sn), and silicon (Si) alloying anodes. The results of this research could have significant benefits to advance battery technologies with Li metal, Si, and Sn anodes, which have the potential to significantly surpass current Li-ion battery technologies in terms of performance and cost. If successful, these batteries could rapidly advance the adoption of electric vehicles for reduced emissions, greater efficiency, and increased domestic energy security. The PI will support the research experiences of graduate and undergraduate students, integrate the research with courses, and communicate the work to the broader community. For Li metal anodes, the in-operando imaging experiments are focused on dendrite nucleation and initial growth at high resolution in standard electrolytes. The imaging will utilize the laboratory-scale nano-scale resolution (50 nm) X-ray computed tomography (nano-CT) instrument. The instrument features Zernike phase contrast optics for imaging low Z materials like Li. A key advantage of nano-CT versus transmission or scanning electron microscopy is there is no need for vacuum and standard electrolytes can be used. In addition, the nano-CT images large volumes that match electrode length scales rather than the thin slices of liquid TEM cells. The experiments focus on the controlled introduction of micro/nano-scale physical and chemical features and characterizing their impact on problematic electroplating and the control of alloying in Si and Sn anodes. A key goal is to identify the surface and particle features that destabilize electrodes and yield dendrite nucleation and Li-alloying particle fracture. The 4D mapping of alloy phase nucleation and propagation will offer new insight into the stable phases of those systems, the particle/electrode morphology effects, and particle-particle interactions. The fundamental knowledge extracted from this imaging can then be applied to advancing the performance and safety of these electrodes.