What role does SINTEF play in modifying the surfaces of electrodes and separators, and why are these modifications important? Can you share some examples of how these modifications can improve the components?

SINTEF’s role is to chemically modify the surfaces of battery components, such as electrodes and separators, before battery assembly.

Modifying the surfaces/interfaces of these components increases the compatibility between electrodes and separators, and enhances the wettability of the separators, which leads to improved ionic conductivity. Improved compatibility between the battery elements in contact can also enhance mechanical stability by preventing delamination during the contraction and expansion that occurs during charging and discharging cycles.

Modifying the interfaces of battery components does not affect the bulk properties of the materials and can be tailored for each specific material.

An example of such a modification is grafting hydrophilic polymer chains of nanometer-scale thickness to improve wettability and ionic conductivity.

What testing and characterization methods does SINTEF use to evaluate the modified electrodes and separators?

We use the following methods:

Contact angle measurements: The wettability/hydrophilicity of the modified interface is assessed by measuring the contact angle of a liquid (in this case, the electrolyte) on the modified surface. A decrease in contact angle indicates increased surface hydrophilicity when using polar solvents for the measurement, and vice versa.

Scanning Electron Microscopy (SEM): SEM is used to generate high-resolution images of changes in the morphology of the modified interfaces.

Energy Dispersive X-ray Spectroscopy (EDS): EDS is used for elemental mapping or spot chemical analysis, helping to identify new elements introduced on the modified surface.

Backscattered Electrons (BSE): BSE can be used to discriminate between phases based on mean atomic number (commonly related to relative density).

Mercury porosimetry: This method is used to assess material porosity before and after the modification process.

Fourier Transform Infrared Spectroscopy (FTIR): FTIR is used to identify organic or polymeric materials grafted onto the surfaces.

What challenges are you addressing in this area?

Tuning the parameters of the modification to meet the targeted properties is specific to each material and must be adjusted each time the material or material composition changes. Achieving a uniform modification across the surface is also a significant challenge, along with ensuring the reproducibility of both the modification process and the characterization, as the modifications occur at the atomic/nanometer scale.