In order for there to be a partnership (Joint Venture), each party must bring something to the table.  Lac would bring the supply of lithium from a US production facility.  This facility isnot et in existince today.   Electrovaya would have to bring something to the table also.  Electrovaya just announced a soild state cell design in a coin package and has promised a pouch sized cell in the first calendar quarter of 2022.

Electrovaya Inc., (TSX:EFL; OTCQB:EFLVF), a lithium ion battery manufacturer with industry-leading performance and substantial intellectual property, today announced that its research division, Electrovaya Labs, has produced promising initial test results using a proprietary approach for a solid state (NMC cathode/lithium metal anode) battery. The initial results have demonstrated minimal capacity fade, and multiple tests have demonstrated the repeatability of the performance with coin cells (please see Figure 1) at room temperature.

https://electrovaya.com/press/electrovaya-labs-announces-initial-solid-state-battery-results/

About 6 months ago Electrovaya purchased a cell production line from a defunct battery manufacturer in Michigan.  Electrovaya has said they were going to recondition this equipment to manufacture their cell.  Well I believe the NEW pouched cells will come from this production line.  I call it a pilot plant as the work is being performed via the Lab and paid for thru the R&D budget.  Some commenters on Agoracom have complained recently about the high R&D budget.  Anyway time will tell so I might as well sit back and watch!!