Nickel and gold miner IGO Limited has snared a minority stake in Australia's top lithium mine and a foothold in lithium processing in a $US1.4 billion ($1.9 billion) deal with struggling Chinese battery metals company Tianqi.

Tianqi, under pressures from its lenders, is selling IGO a 24.99 per cent stake in the Greenbushes mine in Western Australian and a 49 per cent per cent stake in its troubled lithium hydroxide plant at Kwinana south of Perth.