JAKARTA (Reuters) -A lithium-ion battery plant by an Indonesian company and China's CATL is expected to be in operation by the end of 2026 with initial capacity of 6.9 gigawatt hours, an Indonesian official said on Sunday.

The plant is expected to expand to produce electric vehicle batteries with storage capacity of up to 15 GWh, said energy ministry spokeswoman Dwi Anggia, adding the output will be sold to domestic and overseas markets.

The venture by Indonesia Battery Corp and Chinese giant Contemporary Amperex Technology Co is part of a $6 billion power battery project signed in 2022 by Indonesian companies, including state-miner PT Aneka Tambang Tbk, and a CATL consortium. The partnership spans nickel mining and processing, EV battery manufacturing and battery recycling.

Indonesian Energy Minister Bahlil Lahadalia, speaking at the project's groundbreaking, said the plant might also produce a type of battery to store energy from solar panels.

"With the battery for solar panels, the total production capacity of this plant could reach up to 40 GWh," he said, adding that discussion with the project owner was continuing.

The battery plant will be built in West Java, while the remaining subprojects will be in eastern Indonesia's nickel-rich province of North Maluku.

The government of Indonesia, home to the world's largest nickel reserves, has set an ambitious target of producing some 600,000 EVs by 2030. That would be around 13 times the number sold in Indonesia last year.