The liquid heating and cooling system in the Chevrolet Volt battery enabled GM to make more room for battery cells.
"Standard auto coolant circulates through 144 metal plates, called fins, between each of the Volt hybrid battery’s 288 cells. The fins are only 1mm thick, but coolant still circulates through channels in them. When the battery needs to warm up, a heating coil warms the fluid.Batteries in electric cars from startup Tesla Motors Inc. are also liquid-cooled."
"The length of the warranty stems in part from GM's confidence in the Volt's liquid heating and cooling system, which GM says extends the battery's life by keeping it at optimal temperatures. The Volt is the only such mass-market vehicle with a liquid-powered thermal management system, GM said."