NEC Corp. of Japan said today that it had succeeded in a second attempt to acquire a unit of A123 Systems LLC, an American provider of green-energy technologies that was funded by the Obama administration before filing for bankruptcy protection in 2012, the Wall Street Journal reported today. NEC has agreed to buy a division of A123 that provides power storage systems to alternative energy plants. NEC said that it would pay about $100 million to acquire the business from Wanxiang Group Corp., a Chinese company that bought A123, including its automotive battery business, during the bankruptcy proceedings for $257 million.