According to news reports, the company's cylindrical lithium-ion batteries will power SpaceX's next-generation Starship, which completed its fifth orbital test flight last month.
SpaceX, which has traditionally relied on in-house battery production, plans to use the spacecraft for its Mars exploration missions and NASA's Artemis lunar program.
LG Energy Solution has neither confirmed nor denied the reports.
The deal comes as LG Energy Solution, already a supplier to Musk's electric vehicle company Tesla Inc., seeks to diversify its portfolio amid slowing growth in the electric vehicle market.
The company has been expanding its presence in non-automotive sectors, including energy storage systems.