NEXUS · Next Generation of Artificial Heterointerfaces as Building Blocks for Energy Materials

In an era of rapid green transition changes, interfaces lie at the heart of the advances in most energy conversion and storage technologies, including batteries, Power-to-X and electrolysis. Depending on the type of device, these technologies rely upon the fast transport of atomic and electronic species across the solid-solid, solid-liquid and solid-gas interfaces. Developing viable solid-state devices requires a fundamental understanding of how ions move at the interface between two solid materials stacked together. Despite half a century of sustained research into interfaces, we still cannot answer the most critical questions about the role of interface symmetries and finding pathways for engineering fast ionic transport at room temperature. The underlying motivation to find the answers is clear: fast transport of ions provides an opportunity to accelerate energy technology. However, the fundamental science required is extremely challenging: (1) the interfaces are buried in bulk structures and (2) possible combinations of materials are limited by the rules of epitaxy. Imagine a future where the precise tuning of materials can take place according to our aspirations by assembling ultrathin layers into new artificial heterostructures. NEXUS is the epitome of this future. In NEXUS I seek to take a leap from our present knowledge by creating artificial oxide heterostructures and hybridizing their physical properties by directly stacking freestanding membranes with different crystal structures and orientations (Figure 1). In this way I will realize novel structures with fast ionic paths potentially breaking fundamental limitations of existing energy devices. During the last decade I pioneered and matured new sets of oxide-based interfaces, exhibiting an exceptionally colourful palette of properties. The approach of NEXUS is radically different from the past work and will provide fundamental breakthroughs in the study of fast ionic transport across interfaces.