When manufacturers coat a battery electrode, what happens in the minutes while the wet layer dries can make or break performance. Particles can spread evenly, sink or pile up near the surface, changing how current flows once the cell is built. A Drexel-led team reports a simple electrical way to watch those patterns form in real time.
The study, published in Langmuir, was led by Emre Baburoglu, a recent PhD. graduate, with faculty co-authors Nicolas J. Alvarez, PhD, and Maureen H. Tang, PhD, in Drexel’s Department of Chemical and Biological Engineering.
The group miniaturized a classic four-point resistivity probe into a chip-scale sensor. A small current flows through two outer lines while voltage is read between two inner lines. By changing the distance between the lines, the probe samples different depths of a drying film. As the liquid evaporates and particles move, the electrical resistance shifts in telltale ways that reveal whether material is distributing evenly, settling toward the current collector, or forming a dense skin at the top.
“We took a field method from geophysics and scaled it to the lab,” Baburoglu said. “By adjusting the probe spacing, we can read what is happening near the surface or deeper in the coating as it dries.”
In tests on model films, the electrical signal tracked the governing drying regime, matching predictions from physical and heuristic models. Because the metric does not require separate thickness measurements or imaging, it could slot into existing coating lines as an in situ quality check.
“This gives battery makers a real-time window into drying,” Tang said. “Catching problems like binder migration or uneven particle networks early can reduce defects and improve consistency at scale.”
The team notes that the low-cost approach complements current factory tools and could aid process tuning for lithium-ion cathode and anode coatings.
