R&D Cathode Uniformity Study
For R&D cells, getting an accurate mass for your cathode active material is absolutely crucial. Unfortunately, weighing individual R&D cathodes can be expensive and time consuming. Therefore, this customer wanted to know if they could get away with using a nominal cathode weight instead. As a first step, we did a standard cathode casting, tracked all of the cathodes that came from it (left), and mapped out their masses (right).
We repeated this process for (2) castings and looked at the data. The most striking observation was the fact that all of the cathodes with masses > 1 standard deviation below the average seemed to come from the same location on the casting.
Here's how the mass distribution looks for both cathodes combined, with and without the troublesome section included. By simply discarding this section of the casting we were able to reduce the standard deviation but the yield dropped by 10%.
In a slightly-related test, we then wanted to know how weighing cathodes inside the glovebox vs. outside in the lab affected the measured mass. Gloveboxes make everything harder, so if a delicate process like cathode weighing can be done in the lab instead, it could shave off some valuable R&D time.