Crystal Orientation Engineering for Energy Storage and Conversion Applications.

Nanoscale material design is crucial to the development of efficient renewable energy and storage technologies. While conventional research paradigms have emphasized material morphology, crystal polymorphs, and defect engineering, recent years have witnessed an emerging research interest in crystal orientation engineering since it can exploit anisotropic material properties to significantly enhance  emerging energy storage and conversion applications. Herein, a comprehensive review of engineering the crystal orientation of materials to improve various energy conversion and storage technologies is provided. First, we discuss the effect of crystal orientation on material properties, including electrical conductivity, dielectric constant, surface energy, surface electronic structure, atom/molecule adsorption ability, and ionic conductivity. Then, the techniques to characterize the crystal orientation, including X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and optical microscopy, are reviewed. After that, effective strategies to engineer crystal orientation using both bottom-up and top-down approaches are summarized. The advances in crystal orientation engineering in energy conversion (electrocatalysis, solar cells, and nanogenerators) and storage (metal anodes, non-metal-based electrode materials, and solid electrolytes) applications are subsequently discussed. Finally, future perspectives on the potential of crystal orientation engineering and its impact on emerging energy transition technologies are summarized.