Korean battery makers like Samsung SDI, LG Chem and SK Innovation are on alert after Beijing tightened standards for electric car batteries.

The move makes it more difficult for foreign battery makers to get certification to sell their products. Xinhua on Wednesday said China's the Ministry of Industry and Information Technology announced the revision on Tuesday. It is expected to go into force next year.

They drastically raise the bar for the annual output of certified lithium-ion battery makers from 0.2 gigawatts/h to 8 gigawatts/h. They also state that suppliers must not have been involved in serious EV battery-related accidents over the past two years.

"Only two companies in China meet the standards at the moment, BYD and OptimumNano," an industry insider said. "Korean battery makers are at risk of having to stop sales in China."