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Rationally designed architected materials have attained previously untapped territories in materials property space. The properties and behaviours of architected materials need not be stagnant after fabrication; they can be encoded with a temporal degree of freedom such that they evolve over time. In this Review, we describe the variety of materials architected in both space and time, and their responses to various stimuli, including mechanical actuation, changes in temperature and chemical environment, and variations in electromagnetic fields. We highlight the additive manufacturing methods that can precisely prescribe complex geometries and local inhomogeneities to make such responsiveness possible. We discuss the emergent physics phenomena observed in architected materials that are analogous to those in classical materials, such as the formation and behaviour of defects, phase transformations and topologically protected properties. Finally, we offer a perspective on the future of architected materials that have a degree of intelligence through mechanical logic and artificial neural networks.

The ability to design a particular geometry of porous electrodes at multiple length scales in a lithium‐ion battery can significantly and positively influence battery performance because it enables control over distribution of current and potential and can enhance ion and electron transport. 3D architecturally designed carbon electrodes are developed, whose structural factors are independently controlled and whose dimensions span micrometers to centimeters, using digital light processing and pyrolysis. These free‐standing lattice electrodes are comprised of monolithic glassy carbon beams, are lightweight, with a relative density of 0.1–0.35, and mechanically robust, with a maximum precollapse stress of 27 MPa, which facilitates electrode recycling. The specific strength is 101 kN m kg−1, comparable to that of 6061 aluminum alloy. These carbon electrodes can reach a mass loading of 70 mg cm−2 and an areal capacity of 3.2 mAh cm−2 at a current density of 2.4 mA cm−2. It is demonstrated that this approach allows for independent design of structural factors, i.e., beam diameter, electrode thickness, and surface morphology, enabling control over Li‐ion transport length, overpotential and battery performance, not available for slurry‐based electrodes. This multiscale approach to design of electrodes may open substantial performance‐enhancing capabilities for solid‐ and liquid‐state batteries, flow batteries, and fuel cells.

Gas diffusion electrodes (GDEs) have shown promising performance for the electrochemical reduction of CO2 (CO2R). In this study, a resolved, pore scale model of electrochemical reduction of CO2 within a liquid-filled catalyst layer is developed. Three CO2 mass transport regimes are identified in which the CO2 penetration depth is controlled by CO2 consumption in the electrolyte, CO2 conversion along the solid-electrolyte double-phase boundaries (DPBs), and CO2 conversion concentrated around the gas–solid–electrolyte triple-phase boundaries (TPBs). While it is possible for CO2R to be localized around the TPBs, in systems with submicron pore radii operating at <1 A cm–2 CO2R will be distributed across the DPBs within the catalyst layer. This validates the assumption of pore-scale uniformity implicit in popular, volume-averaged GDE models. The CO2 conversion efficiency depends strongly on the governing mass transport regime, and operational-phase diagrams are constructed to guide the catalyst layer design.

Nanoarchitected Cu−Si core−shell lattices were fabricated via two-photon lithography and tested as mechanically robust Li-ion battery electrodes which accommodate ∼250% Si volume expansion during lithiation. The superior mechanical performance of the nanolattice electrodes is directly observed using an in situ scanning electron microscope, which allows volume expansion and morphological changes to be imaged at multiple length scales, from single lattice beam to the architecture level, during electrochemical testing. Finite element modeling of lithiation-induced volume expansion in a core−shell structure reveals that geometry and plasticity mechanisms play a critical role in preventing damage in the nanolattice electrodes. The two-photon lithography-based fabrication method combined with computational modeling and in situ characterization capabilities would potentially enable the rational design and fast discovery of mechanically robust and kinetically agile electrode materials that independently optimize geometry, feature size, porosity, surface area, and chemical composition, as well as other functional devices in which mechanical and transport phenomena are important.