In late February, Chinese automaker BYD won regulatory approval to begin selling electric vehicles in Beijing and Shanghai. Once the darling of international green-energy advocates and investors, the Shenzhen-based company has in recent years seen modest sales in China and shrinking profits. One hurdle has been an insufficient network of nationwide charging stations. Today one of the major obstacles to ramping up electric vehicle sales in China is infrastructure. Electric cars and charging networks present a classic chicken and egg conundrum: Consumers are understandably wary of purchasing electric vehicles while facilities to charge them remain scarce in China. One sticking point has been a matter of technology. Power companies in China want to push battery-swapping stations, where a driver can exchange a depleted battery for a fully charged one in a matter of minutes.