I missed this thread earlier. Interesting how everyone jumped to the conclusion that terminal temp rise is caused by terminal contact resistance heating.
I have a spreadsheet that I have been developing for a while to predict internal cell temp rise based on cell current demand for a thick electrode (120-150 um) 280 AH cell. I did not have 100% confidence because I had to make a few guessimates on heat transfer properties for cell internal material.
Anyway, the interesting and surprising thing is my spreadsheet predicted 34 deg C cell internal temp from a starting ambient cell temp of 25 degs C for a discharge of 0.6 CA rate. I am sure there will be some extra terminal contact resistance heating that will increase terminal temp some amount above battery internal temp but it appears much of the temp rise shown at the terminal is due to cell internal heating at the 0.6 CA discharge rate. All of the internal cell copper foil layers for anode connections and aluminum foil layers for cathode connections conduct the internal cell heating directly up to the terminals.
The real concern should be the internal heating of the cell which does more permanent damage to the LFP cell.
Just for fyi, the spreadsheet predicts an internal cell temp of 45 degs C at a 1 CA sustained discharge rate. This is why I believe the thick electrode cells should not be used with a sustained discharge or charge current above 0.5 CA. Think about this when cells are tightly packed together like sardines in a can. The irony of contradiction is cell compression does not provide much benefit until current is so high to cause cell internal heating but tightly compressing the cells together makes it harder for cells to dissipate internal heating.
Because of the thick electrode design, which is done to maximize cell AH for its size and weight, to the detriment of maximum CA current handling capability, these 280 AH cells will experience local layer ion starvation onset around 0.5 CA current demand. This causes cell losses to increase at a faster rate above 0.5 CA. At 0.5 CA sustained current there is about 11-12 watts of internal cell heating. At 1.0 C sustained current there is about 35-40 watts of internal cell heating.
Indeed, even for very light cell discharge (40 amps) I measure a cell temperature rise of 5 degrees C during the last 30 to 40 ams hours out of a cell.
However, I have found that I must thoroughly clean each cell and busbar connection every single time that I assemble/disassemble a pack. I even bought a thermal camera to be able to see both the cell temperature from discharge, and bad connections. It has turned out to be very useful in diagnosing or preventing any problems.
I am of the opinion the latest flood of bloated cells from vendors is likely due to over discharge, rather than over charging. But that is my opinion, not facts.
I agree with your analysis that it is very much in your own best interest to keep discharge rates low, below 0.5 C, and preferably even lower.