Electric vehicle demand in the past five years has soared in the US. The same is true worldwide. By the end of 2014, more than 700,000 total plug-in vehicles had been sold worldwide (plug-in hybrids and pure battery electrics), up from about 400,000 at the end of 2013. As of 2015, dozens of models of electric cars and vans are available for purchase, mostly in Europe, the United States, Japan, and China.
A major reason for the rapid jump in EV sales is the rapid drop in the cost of their key component -– batteries. The energy stored in a battery is measured by kilowatt-hour (kWh). The more kWh stored, the further the car can go on one charge, so a key metric for battery economics is the cost per kWh. The lower the cost, the cheaper it is to build an electric car with a significant range.