Complementary sample preparation strategies (PVD/BEXP) combining with multifunctional SPM for the characterizations of battery interfacial properties

Abstract

The cathode/anode-electrolyte interfaces in lithium/sodium ion batteries act as the “gate” for the ion exchange between the solid electrode and liquid electrolyte. Understanding the interfacial properties of these solid-liquid interfaces is essential for better design high-performance lithium/sodium ion batteries. Here, we provide a novel method for studying solid-liquid interfacial properties of battery materials through combining physical vapor deposition (PVD) and beam-exit cross-sectional polishing (BEXP) followed by controlled environment multifunctional Scanning Probe Microscope (SPM). In this method, commercial battery materials can be either directly grown on the current collector substrates, or polished by obliqued Ar-ion beams to get a nanoscale flat surface which allows the multifunctional SPM to study sample directly in the liquid electrolyte or in protective oxygen/H 2 O free environment. This approach allows to investigate wide range of interfacial properties, including surface morphology, internal cracks, mechanical properties, electronic/ionic conductivity and surface potential, with nanoscale resolution in-operando during the battery cycles as well as post-mortem. PVD and novel BEXP methods were introduced to prepare battery powder materials as perfect specimens for nanoscale SPM characterization. Various physical/chemical properties of battery materials can be probed on the as-prepared specimens under liquid electrolyte using in situ/operando SPM techniques. Ex situ/post-mortem analyses based on the controlled environment multifunction SPM characterizations can be achieved in the BEXP polished degradation battery electrodes.

Controlling Interfacial Reduction Kinetics and Suppressing Electrochemical Oscillations in Li4Ti5O12 Thin‐Film Anodes

“…Real‐space observation of the SEI formation in the liquid environment on both electrodes surface can provide direct evidence for this hypothesis. Operando AFM has demonstrated its versatility for the real‐space observation of SEI formation in battery materials, [ 25 ] however, few reports have applied shear vibration interactions between the tip–sample, which is extremely sensitive to the viscoelastic SEI layer, to monitor the dynamic growth of SEI layers. We therefore first applied the operando SFMM technique here to monitor the initial dynamic SEI formation process on bare LTO and on the AZO(60)–LTO electrode surface.…”

Multiscale Investigation of Sodium‐Ion Battery Anodes: Analytical Techniques and Applications

“…[ 198 ] and Daboss et al. [ 204 ] In addition, non‐contact imaging modes for in situ studies also minimize such artefacts [ 205 ] Embedding and subsequent cross‐sectioning of e.g., composite carbonaceous negative electrode materials via mechanical polishing significantly reduces S z values (maximum height of a defined area) from several microns to submicron. [ 204 ] This reduction minimizes artifacts and enables the direct observation of SEI formation.…”

“…AFM techniques are sensitive to the roughness of the material surface, which may lead to erroneous data due to AFM tip-related artefacts. [203] In contrast with static force microscopy, AFM imaging studies require careful sample preparation for electrode surfaces with high roughness, as demonstrated by Luchkin et al [198] and Daboss et al [204] In addition, non-contact imaging modes for in situ studies also minimize such artefacts [205] Embedding and subsequent cross-sectioning of e.g., composite carbonaceous negative electrode materials via mechanical polishing significantly reduces S z values (maximum height of a defined area) from several microns to submicron. [204] This reduction minimizes artifacts and enables the direct observation of SEI formation.…”

Operando nano-mapping of sodium-diglyme co-intercalation and SEI formation in sodium ion batteries' graphene anodes

“…The sample cross section was prepared by beam-exit cross section polishing. 18,19 The graphitic characteristic of the FLG model electrode was confirmed by a confocal Raman microscope (LabRAM HR Evolution, Horiba) with an excitation wavelength of 532 nm. The chemical components of SEI were studied by XPS using Kratos Analytical AXIS Supra spectrometer with a monochromatic Al Ka 1486.7 eV x-ray source, operating at 15 kV and 15 mA, equipped with an electron gun for charge neutralization.…”