The need for batteries with improved performance compared to conventional Li-ion technologies is rapidly growing. The capacity, charging speed, and stability of the batteries required for future technologies such as electric cars and renewable energies are continuously improved. At the same time, the cost and the time for battery production must be reduced to satisfy the market demand. To fulfill such requirements, more and more battery producers focus on dry-coating processes. These new processes allow for the production of electrodes without solvent, sparing time and money. For such manufacturing processes, the raw materials, blended in powder form stay dry from the start until the coating process. Therefore, powder characterization is important to ensure good quality and good processability for dry-coating processes.

Polytetrafluoroethylene (PTFE) is a binder appreciated for its plasticizing properties for dry electrode production. This polymer is generally added to the active material and fibrillated, a process aiming to create fibrils from the agglomerated PTFE. These fibrils allow after calendering to produce a free-standing film from the powder made of the active material and conductive additive (with the binder). Then, this film is coated on a current collector to produce an electrode. This sheet must have adequate mechanical properties (consistency) which directly depend on the fibrillation.

While fibrillation is an important step for dry-coating based on PTFE, adequate methods are missing for characterizing and quantifying a ‘’degree of fibrillation’’ after the process. In this work, we show an innovative technique to characterize the powder material after PTFE fibrillation. Powder blends made of Lithium Iron Phosphate (LFP), PTFE, and carbon black were characterized with GranuPack, an improved tapped density method. The metrics measured by this instrument were found to be correlated to the degree of fibrillation of the powder, allowing to quantify it. Specifically, the packing dynamic seems related to the particle mobility in the blend, highly influenced by the entanglement of PTFE. This entanglement increases with fibrillation. Moreover, physical interpretations can be found by comparing the powder blend with granular chains. With a better understanding of the powder blend behaviour and a method to quantify PTFE fibrillation, dry-processes will be rapidly improved to produce batteries with high energy density.