Failed technology gambles and a half-decade of jockeying among suppliers have top auto makers increasing choosing LG, Samsung Electronics Co. SDI unit and Panasonic Corp. PCRFY -0.79 % The three are emerging as the early winners amid a shift by car companies away from in-house efforts, traditional battery makers and startup ventures. Their quick rise as key suppliers to European, Asian and U.S. car makers is remarkable for an industry that typically insists on reducing risks by building key components such as engines in-house—or using lots of suppliers for less-critical parts. In part, experts say few companies so far have shown they can meet the challenge of building advanced batteries with the quality, weight and cost expectations that auto makers demand. And the technology is moving so fast that few auto makers have tried to master the exotic chemistry required. Of course, electric cars remain […]