The SIMPEL project addresses the design and development of a new generation of highly efficient solid state energy storage devices based on Solid Oxide Electrolysis Cells (SOECs) able to convert electricity into pressurized hydrogen suitable for direct injection into the grid or tank storage. The SIMPEL concept is based on the combination of high-fidelity multiphysics simulations and advanced manufacturing of disruptive geometries for developing microtubular and complex 3D shapes with optimized engineered interfaces (tuned from the cm- to the μm-scale). More precisely, SIMPEL will deliver complete SOEC cells and short stacks with unique mechanical properties able to operate at high pressure based on advanced geometries and novel joint strategies.