Ram, re: yields, please refer to my post:
Message 12394620
Since each cell is hooked up individually in the conditioning ovens, they monitor each cell as it goes through the initial charging process (the 'formation charge,' which recall is most effective when performed at elevated temperatures, hence the use of ovens). A failed cell is individually flagged at this point.
When the cells are then put in the quarantine chamber (for a nominal 2-week holding period, at last report), they are not individually monitored in this way (to our best knowledge). Whether they check each cell for charge retention or not, at the end of this holding period and prior to shipping, is a good question to ask at the SM. It certainly seems possible to implement a cell-by-cell test at this step, if it is desirable... perhaps they now do.
The most sensitive part of the process is the 'recipe' at the front end, and the thin-film coatings, and this is where statistical sampling of materials for microscopic inspection for material defects, etc is the best that can be done.
Once an individual bicell is constructed, and electrodes attached, they perform an automated impedance check of each bicell prior to stacking into cells.
This is what we know so far. Looking for more answers and/or guidance at the SM (to the extent it can be done without divulging too much proprietary information).
Regards, Rich |
