LG Energy Solution, a spin-off of LG Chem, has signed a long-term deal to supply secondary battery cells for American electric bus maker Proterra.

The Korean secondary battery maker said that it has won a 5-year contract to supply cylindrical secondary battery cells for the U.S. electric bus maker from 2023 through 2028.

Founded in 2004 by former employees of EV maker Tesla, Proterra is the largest US. Electric bus maker in terms of market share, holding a 60% share.

Under the terms of the agreement, LG Energy Solution is required to produce the cylindrical batteries in its U.S. manufacturing facilities to supply them for Proterra.

LG is now operating a 5GWh-capacity secondary battery cell manufacturing facilities in Michigan, U.S.

On top of that, Ultium Cells, a JV between LG and GM is now constructing a 35GWh facility and a 35GWh facility, which are scheduled to come online in 2022 and 2023, respectively.

LG has also its own plan to invest 5 trillion won to build one more battery cell manufacturing facility in the U.S.