The SOLiDIFY project proposes a unique manufacturing process and solid-electrolyte material to fabricate Lithium-metal solid-state batteries – known as Gen. 4b on the EU battery roadmap. The concept is based on a solid nanocomposite electrolyte or nano-SCE. It is made by a sol-gel reaction which is used advantageously for a liquid-to-solid approach in the fabrication of the composite cathode and the solid-electrolyte separator. The general strategy to reach the target energy density of 1200Wh/L (400Wh/kg) in 20 minutes charging time is: (1) enabling the integration of high-energy NMC active materials and (2) development of new electrode architectures for high mass loading and enabled by the liquid-to-solid approach. An added imposed challenge is a water-based cell assembly process. To this end, suitable protection of the high-energy NMC powder with ALD thin-film coatings is pursued. Finally, thin lithium foils with protective artificial interphase coatings will be developed for lamination on the nano-SCE separator. The main goal of SOLiDIFY is to bring the liquid-processed solid-state cell fabrication concept from demonstration in the lab (TRL3) to demonstration of prototypes in pilot line (TRL6), with upscaling of the concept both towards (1) the development of manufacturable materials and processes and (2) the discovery of full cell assembly schemes with ultimate demonstration of 1Ah pouch cells. The material research will focus on (1) solutions enabling the upscaling process and manufacturability and (2) further improvement of cell integration steps to enhance performance. Manufacturable parameters such cost, environmental impact and recycling will also be handled. The larger scope of the SOLiDIFY project entails the development of a novel and potentially European-lead solid-state battery technology with fully covered EU value chain.