The empty cell was purchased by Dahn's group, but likely built to Dahn's specification, and the choice of electrolyte additives added by Dahn was the core discovery in Dahn's latest paper. Tesla and Dahn did not invent single crystal (micrometer size scale) NMC 532 cathodes but Dahn's group has been very focussed on researching their properties for several years now. Dahn has published many papers on how to optimise cell properties to get the most from the advantages of the single crystal cathode structure.
Dahn and Tesla actually filed their first patent on choosing electrolyte additives for single crystal NMC532 cells back in July 2017. US20190036171 NOVEL BATTERY SYSTEMS BASED ON TWO-ADDITIVE ELECTROLYTE SYSTEMS
The main new discoveries made by Dahn which are combined to contribute to the state of the art 1 million mile cell life are:
The experiment in the latest 1m mile paper used single crystal NMC532/artificial graphite with a Ti-based coating pouch cells (240 mAh at 4.3 V) supplied by Li-FUN Technology (Based in China) - with the electrolytes then added by Dahn's team. The artificial graphite used was KaijinAML-400 from Kaijin, China.
I don't think any of these key discoveries are necessarily restricted to the specific NMC cathode or anode or the pouch format used above. Dahn's team has also published papers on how to make single crystal NCA cathodes for example.
Synthesis of Single Crystal LiNi0.88Co0.09Al0.03O2 with a Two-Step Lithiation Method. I doubt the cell chemistry Tesla is developing in its commercial cell R&D lab is the exact same NMC532 chemistry tested publicly by Dahn, but it will use the key ideas discovered by Dahn.