Interview with Adrian Lutey, Researcher at the University of Parma
What is University of Parma’s role within GIGAGREEN?
The role of the University of Parma within GIGAGREEN is the simulation of laser-textured current collectors to aid selection of the best configuration in terms of laser processing parameters and surface morphology. An important aspect of improving the lifespan of next-generation Li-ion batteries is ensuring adequate mechanical strength during charge and discharge cycling. This is particularly critical for high energy density materials such as silicon that undergo very large volumetric changes with lithiation and delithiation, as well as solvent-free electrodes where adhesion strength may be an issue. Laser-texturing of current collectors will be employed within GIGAGREEN to increase the interface area and improve adhesion between the current collector and active material, reducing interface resistance and improving cell lifespan.
Why are simulations key for the project? How do they work?
The simulation of laser-textured current collectors is key for the project as it provides insight into favourable surface characteristics for achieving project key performance indicators in terms of substrate-coating interface area and adhesion strength. Ultrashort pulsed laser texturing can achieve a diverse range of surface morphologies ranging from hundreds of nanometres to tens of micrometres in size. Simulations are therefore necessary to guide experiments based on physical phenomena taking place to reduce the number of tests that must be performed and ultimately achieve the project objectives more rapidly.
Simulations in GIGAGREEN will be based on the finite-element method (FEM), where the simulation domain is discretised into simple elements and the resulting set of differential equations is resolved numerically. A representative section of each laser-textured electrode will be considered, imposing volumetric changes due to lithiation and delithiation for each electrode configuration and evaluating the resulting interface stresses. The surface topography of laser-textured current collectors will firstly be represented with simple analytical equations, allowing parametric studies to be carried out to evaluate changes in interface area, active material penetration and interface stresses with variations in surface structure type, period and aspect ratio. Preliminary results have already provided clear indications as to the nature of optimised surface structures. Subsequently, the surface topography of actual laser-textured current collectors will be acquired with optical interferometry and atomic force microscopy, allowing profile data to be imported into simulations to provide more accurate predictions and account for more complex surface characteristics resulting from ultrashort pulsed laser irradiation.