Cross-Sectional Preparation of Challenging Devices and Their Scale-Bridging Micro- and Nanoanalytical Characterization

Abstract

Complex devices like batteries, fuel cells or organic sensors and solar cells are commonly assembled from multiple functional components with different materials properties. To gain a fundamental understanding of the microstructure-property relations of such complex macroscopic structures, their degradation and failure mechanisms by complementary scale-bridging microscopic and spectroscopic techniques, it is desirable to prepare cross sections of entire devices or parts. Most challenging is the generation of electron transparent cross-sectional samples for investigation by (cryo) transmission electron microscopy (TEM); preparing TEM samples of devices consisting of different material classes may be utmost difficult. Therefore, TEM sample preparation is often preceded by the disassembly of a device down to individual components rendering an investigation of relations between the individual components impossible. (Cryo-)ultramicrotomy as well as plasma-FIB as advanced cross-sectioning techniques for challenging samples may solve those issues. Both are capable to generate ultra-thin, electron transparent cross sections of hundreds of micrometers in size being larger than the typical thickness of modern devices. In this contribution, we demonstrate the capabilities of modern (cryo-)ultramicrotomy in conjunction with advanced TEM to characterize such sensitive or reactive and thus challenging devices down to the atomic scale. Examples include battery parts, PEM fuel cells and novel flexible all-organic electronics. The achieved thickness of those cross sections is commonly of the order of a few 10 nm, which even allows for atomic-resolution imaging and advanced spectroscopy for microstructure and defect analyses as well as compositional and chemical-bond investigation, respectively. Hepp et al., Trained Laser-Patterned Carbon as High-Performance Mechanical Sensors, NPJ Flex. Electron. 6 (2022), 3, DOI: 10.1038/s41528-022-00136-0 Beaupain et al., Reaction of Li1.3Al0.3Ti1.7(PO4)3 and LiNi0.6Co0.2Mn0.2O2 in Co-sintered Composite Cathodes for Solid-State Batteries, ACS Appl. Mater. Inter. 13 (2021) 47488-47498, DOI: 10.1021/acsami.1c11750 Li et al., Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy, Science 358 (2017), 506–510, DOI: 10.1126/science.aam6014 Figure 1