Stanford Ovshinsky, a self-taught American inventor and founder of the Ovonic Battery Company in Michigan, patents in 1986 (patent US4623597) an improved version of the nickel-metal hydride (NiMH) battery based on "disordered" electrode alloys — that is, lacking the periodic crystalline structure of earlier designs — which result in substantially higher hydrogen-storage capacity and stability. The basic NiMH battery concept, however, is not Ovshinsky's invention: it was already developed in 1967 at the Battelle-Geneva Research Center, funded by Daimler-Benz and Volkswagen, and a first commercially viable NiMH battery following the classic design was independently demonstrated by Willems and Buschow in 1987. Ovshinsky's specific, decisive contribution is having solved the electrode instability problems that had prevented the technology's large-scale commercial viability for nearly two decades, finally allowing it to replace nickel-cadmium — toxic due to cadmium — in portable electronics and, more visibly, in early hybrid vehicles such as the Toyota Prius. General Motors acquired in 1994 a controlling stake in Ovshinsky's patent for its EV1 electric vehicle, a program the company itself would cancel before the technology's full commercialization, under circumstances Ovshinsky himself publicly questioned.