Toyota has started using the same type of battery Panasonic designed for Tesla in some plug-in hybrids sold in China, media reports said.
The cylindrical batteries are in new Corolla and Levin PHEV hybrid sedans launched this year, a source told cnbc.com.
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The batteries are the same size as those that Panasonic makes for Tesla, the sources said, but the composition is different.
CNBC said the move reflected Toyota's efforts to secure stable supplies of high quality batteries amid the accelerated global shift to electricity powered cars.
The automaker co-developed the batteries with Panasonic over a period of several years as it expanded its lineup of electrified vehicles, according to one source.
A Panasonic spokeswoman told CNBC said the company was not in a position to comment as a supplier while Toyota declined to comment.
The report said Toyota had favoured square, or prismatic, batteries for its vehicles, and uses some manufactured by Panasonic for its hybrids. The two companies announced a joint venture in January to build EV batteries, pooling R&D and manufacturing strengths.
Toyota has also partnered with China's Contemporary Amperex Technology and EV maker BYD for battery procurement.
Toyota is believed to have ordered about 50,000 of the cylindrical batteries, pushing Panasonic's battery plant in Osaka to full capacity, the Nikkei reported.
Panasonic had been the exclusive battery cell supplier for Tesla but that company reportedly is in advanced talks with LG Chem as it seeks to diversify sources of the key component.
