MILAN—The carmaker Stellantis said Monday that it has secured a five-year supply of battery-grade lithium hydroxide in Europe to support its plans to convert to 98 percent electrified vehicles by 2025. Stellantis, the company that combined PSA Peugeot and Fiat Chrysler, signed a binding agreement with Vulcan Energy Resources Ltd. in Germany, which uses geothermal energy to produce the battery-quality lithium hydroxide from brine without using fossil fuels. Vulcan will supply between 81,000 metric tons and 99,000 metric tons of lithium hydroxide over the five-year term of the agreement. All top automakers are working on electric vehicles as fears grow about climate change. Also Monday, Nissan said it is investing 2 trillion yen ($17.6 billion) over the next five years and developing a cheaper, more powerful battery to boost its electric vehicle lineup. Stellantis said its deal supports the decarbonized supply of key raw materials for electric vehicle battery packs. …