EV battery building: Stellantis, LG Energy Solutions still revising the recipe

Lithium-ion cells from the new $5.2-billion battery plant in Windsor will begin finding their way into Stellantis’ North American electric vehicles in late 2024 or early 2025. Inside the massive plant — covering about 100 acres (40 hectares) — the manufacturing process will be broken down into three main steps: electrode production, assembly and formation.

The approach is not drastically different from those used by other battery makers, said Denise Gray, LG Energy Solution’s (LGES) head of external affairs and government relations for North America.

But because LGES will be building soft-shelled pouch cells, there are a few nuances.

Full-scale production is also three years away, leaving time for the process to evolve as the battery maker researches techniques to improve both its cells and its manufacturing process, Gray said.

Building the positive and negative electrodes contained in each battery cell begins with mixing. In one room, cathode material is combined with binding agents in equipment not unlike “big KitchenAid mixers” to form a slurry, Gray said. Anode material, for the negative side of the cell, gets the same treatment in another part of the plant.

Still in separate streams, the cathode and anode materials are applied, respectively, to aluminum and copper foil. The positive and negative electrodes are then each pressed to the correct thickness before being cut down to the proper size and dried to remove any moisture.

ASSEMBLY

The positive and negative electrodes are brought together to form the cell. A specially coated separator is inserted between the two sides to keep them apart and prevent any internal short circuits.

Once the separator is in place, LG’s process for pouch cells departs from other methods for manufacturing cells. Cylindrical battery cells, which closely resemble conventional tubular batteries, are rolled and fitted into enclosures, Gray said. Pouch cells are built by stacking sets of cells and slipping them into their softshelled enclosures.

The partially sealed pouches are then flooded with electrolyte.

“That allows the electrons to go between the positive and negative,” Gray said, “and then you seal [the pouch] up.”

FORMATION

The final step in cell production lasts 10-21 days, Gray said, “This is where the batteries come alive.”

The now-active cells are placed in a warehouse-like environment and charged and discharged to check performance and to detect problems. LG’s target is to have 95 per cent of its cells perform properly through the “aging” process, Gray said. Cells that exhibit problems are discarded, while those that clear quality control are ready to be packaged into modules or sold individually, depending on customer needs.

EV INTEGRATION

To be fitted into EVs, individual battery cells from the new Windsor plant will first be packaged into modules. Sets of modules are then combined with energy management and cooling systems to form a completed battery pack.

There is no fixed number of cells in a module or modules in a pack, Gray said. That means the exact configuration of Stellantis’ batteries will be left up to the automaker.