The challenge of pairing fast charging batteries with high energy density

The Challenge of unifying fast charging and high energy density in batteries

• High-energy anodes for fast charging
• Optimization of anode kinetics
• Targeting of microstructure and texture

Lithium-ion batteries are still limited regarding energy density, fast charging and costs. High-performance electrode materials are needed to overcome the current limitations of electromobility. Currently, the unification of fast charging and high energy density is consistently pursued.

If high-energy anodic materials are charged, the transport pathways for the Li-ions are often restricted. This leads to irreversible accumulations of reactive metallic lithium that result in reduced cell capacity, high inner resistances, shortcuts and, finally, safety issues.

Due to a lack of systematic approaches, the key parameters determining anode kinetics are particle size, shape, and distribution, together with tortuosity and porosity. Their experimental optimization is currently attempted by time consuming and costly trial-and-error due to a lack of systematic approaches in R&D. 
With this experimental method, the impact of one single parameter on a complex battery system is often elusive.

Math2Market joins in your efforts and helps in applying GeoDict to tackle specific issues. In a tailored evaluation project, we train you in using GeoDict optimally for modelling of microstructures, simulation and prediction of properties, as well as visualization and interpretation of simulation results. 
GeoDict supports a variety of import and export file formats (e.g. MATLAB®, Microsoft Excel®), and can mesh and export the generated structures. In this way, GeoDict can be seamlessly integrated into an existing workflow with other software tools. Besides, 
GeoDict can be controlled and run through user-created python macros and scripts. 
After the training, the professional support of Math2Market focuses on keeping the user in the road to success. Yearly software updates guarantee that GeoDict remains at the forefront of scientific developments in material microstructure design.

Contact for evalution project
 

The effective ionic diffusivity in the electrolyte is a key parameter to optimize electrode materials for fast charging. It depends critically on the tortuosity τ, which is a measure of the curvature of the ion transport pathways due to the microstructure of the electrode.  A lower tortuosity leads to higher diffusion of the Li-ions. 
The critical parameter for the active particles in the electrode is the specific active surface, which must be maximized to offer sufficient electrochemically active sites for ion transfer. 
Optimizing tortuosity and specific active surface will prevent bottlenecks for Li-ion transport and intercalation and, therefore, restrict Li-plating. The calculation of the microstructure‘s tortuosity and the effective diffusivity in the electrolyte is carried out using the DiffuDict module. The specific surface area of the active particles is determined within the GrainFind module. 
In the next step, structural parameters like solid-volume-percentage, porosity, and size distribution, shape, and orientation of particles are optimized in the GrainGeo module. A charging simulation with BatteryDict then proofs the reduction of Li-plating.
The Volkswagen Group Innovation is investigating the design guidelines for fast charging anodes using this workflow:

• Increasing active graphite surface by e.g. smaller particle size
• Increasing effective electrolyte diffusion by e.g. particle orientation
• Orienting the particles to expose the prismatic surfaces for Li-ion exchange