Rapid Preparation of Geometrically Optimal Battery Electrode Samples for Nano Scale X-ray Characterisation

Abstract

Rechargeable lithium-based batteries are one of the key enabling technologies driving the shift to renewable energy, and research into novel technologies has intensified to meet growing demands in applications requiring higher energy and power density. The mechanisms behind battery degradation can be investigated across multiple length-scales with X-ray imaging methods; at the nano-scale severe constraints are imposed on sample size in order to obtain adequate signal to noise. Here, we present a novel laser-milling technique to prepare geometrically optimal samples for X-ray nano-tomography. Advantages of this technique include significantly reduced sample preparation time, and a suitable geometry for mosaic acquisition, enabling a larger field of view to be captured at high spatial resolution, thus improving statistics. The geometry of the resulting electrode remains highly suitable for nano-tomography, and yet permits in situ and operando experiments to be carried out on standard electrode coatings, providing new insights into transient phenomena whilst closely mimicking standard electrochemical cells.

Degradation of Layered Oxide Cathode in a Sodium Battery: A Detailed Investigation by X‐Ray Tomography at the Nanoscale

“…Radiographs of the sample (1901 projections) were taken in absorption‐contrast and large‐field‐of‐view (LFOV, 65 µm) mode by rotating the specimen through 180°, with exposure time for each radiograph of 40 s and camera binning 1, which led to a voxel size of 63 nm. Specimens with suitable geometry [ 70 ] for X‐ray CT at the nanoscale were prepared by laser cutting the electrodes by means of a Series/Compact Laser Micromachining System (Oxford Laser) after peeling off the Al foil with the aid of a razor blade and an optical microscope, [ 71 ] and by subsequently gluing these cut portions onto stainless steel (SS) dowels with diameter of 1 mm by epoxy [2,4,6‐tris(dimethylaminomethyl)phenol, Devcon]. The electrodes were exposed to air for preparing samples for SEM‐EDS and X‐ray CT.…”

Multi‐Dimensional Characterization of Battery Materials

“…[76][77][78][79] Such rich multidimensional datasets can be of great value to modelers and experimentalists alike such that it is becoming increasingly more common to release the raw data and procedures via open source repositories and articles. [77,[80][81][82] Such data can feed into highly complex 3D models [82][83][84][85][86][87] providing unparalleled insight into the electrochemistry at these very small scales, see Figure 3c. Additionally, ptychographic methods are also emerging as powerful alternatives for high-resolution imaging.…”

Supercapacitor Degradation: Understanding Mechanisms of Cycling‐Induced Deterioration and Failure of a Pseudocapacitor

“…X-ray CT samples were prepared using a laser micro-machining instrument (A Series, Oxford Lasers Ltd.) containing a 532 nm laser with a spot size of ca. 40 μm following the methods outlined by C. Tan et al [62] The electrodes were cut into a tab consisting of 2 rectangular sections with the smaller section measuring ca. 0.2 mm × 0.08 mm and the larger section measuring ca.…”