Lithium-ion batteries are great for mobile phones and laptop computers. They charge quickly, last [kinda] long and have a good energy-storage-to-weight ratio. However, they also have a worrisome tendency to overheat and burst in flames. Car companies toying with the idea of using electric propulsion to save the world have been trying to get around the problem by walling off individual battery cells or including expensive cooling systems (the Tesla Motors approach). According to TG Daily, German researchers have succeeded in making a non-flammable Li-Ion battery, by replacing the flammable organic electrolyte with a polymer which keeps its solid form. The Fraunhofer Institute for Silicate Research will present a prototype by the end of the month at a conference in Germany. But the inventors caution that it will take three to five years to bring the new lithium-ion technology to maturity– and a few years after that before you see them in electric or hybrid cars.