(Reuters) - A new solid-state lithium-metal battery being developed initially by QuantumScape Corp for electric cars could be powerful enough for use in electric aircraft, a director of the Silicon Valley firm said on Tuesday. “Electric aviation starts to look a lot more attractive and viable when you have this kind of energy density and power,” said J.B. Straubel, chief executive of Redwood Materials and co-founder of Tesla Inc. Backed principally by Volkswagen AG, QuantumScape has spent much of the past 10 years working on a new type of lithium-ion battery that uses a solid-state separator and a lithium-metal anode. Founder Jagdeep Singh on Tuesday released test data to support his claim that QuantumScape’s battery cell will provide a driving range of 300 miles (483 km) or more, can be charged to 80% capacity in 15 minutes, will last for 150,000 miles or more and will be safer and cost less to produce than conventional lithium-ion battery cells with flammable liquid electrolyte. QuantumScape went public in late November after a reverse merger with special purpose acquisition company (SPAC) Kensington Capital Acquisition Corp. In mid-afternoon trade, shares were up 10.6% to $48.83, giving QuantumScape a market value of $18.4 billion. QuantumScape’s battery is still four to five years from production. A joint venture with VW aims to begin manufacturing in 2024-2025, Singh said, and plans eventually to ramp up production to 20 gigawatt-hours a year, about two-thirds the capacity of a new General Motors-LG Chem battery plant in Lordstown, Ohio. GM and other automakers and suppliers are backing potential competitors, including Colorado-based Solid Power (investors include Ford, Hyundai, Samsung), Massachusetts-based Ionic Materials (Hyundai, Samsung, Renault, Nissan) and SolidEnergy (GM, SAIC, SK), also based in Massachusetts.