Scanning Electron Microscopy (SEM) provides high resolution imaging and chemical microanalysis at the micro- or nano-scale. Coupled with powerful cross-sectioning techniques like ion-beam milling, electron microscopy enables researchers to precisely observe the structures, morphology and material distribution. With advanced image analysis methods, the images can be converted into quantitative data that can be correlated directly with battery performance characteristics.
Left image: High quality cross section of LiB cathode (NMC) prepared with broad Argon ion milling
Right image: Studying binder distribution on cathode active material (CAM)
1. Particle morphology and size
SEM can reveal the morphology and size distribution of electrode particles. For example, irregularly shaped particles, cracked particles or agglomerates may lead to poor ion diffusion and contribute to capacity fade.
2. Distribution of active materials
Electron microscopy can show how active materials, such as lithium compounds or transition metal oxides are distributed within the electrode matrix. Distribution of other materials, polymeric binders or carbon nano-tube based conductive agents can also be characterized.
3. Pore structure
Imaging can show the internal pore structure of the electrode material, including the size, shape and distribution of pores important for electrolyte penetration and ion transport.
4. Interface characteristics
The electrode-electrolyte interface (SEI) and electrode-current collector interface are critical for ion transport and electron conduction. Coatings, cracks, or other defects that may influence battery performance can be studied.
5. Structural changes during or after cycling
By comparing images before and after cycling, electron microscopy can elucidate structural changes such as particle cracking, delamination, or electrode/electrolyte interface evolution. Solid state batteries can even be studied in-situ to see Li-transport during charging and discharging cycles.
Contact us to find out how electron microscopy can be applied to your materials.
