Samsung SDI said on Thursday that it had signed a preliminary deal to build an electric car battery factory in China by next year, betting on the growth potential of the countrys electric car market. South Koreas Samsung SDI also said it will form a joint venture by April this year to invest a total of $600 million in the factory and other electric car battery businesses over the next five years. Samsung SDI said the joint venture consists of Chinese parts maker Anqing Ring New Group and an unidentified company owned by Chinas Shaanxi province.