Neutrons are uncharged elementary particles that make up the nuclei of atoms. The prominent characteristics of neutrons, such as high penetrability, high sensitivity to light elements, magnetic in nature and nondestructive property, have paved the way for application of neutron scattering techniques in exploring structural properties of advanced materials. By adopting different scattering geometries, different neutron scattering approaches, including neutron diffraction, small angle neutron scattering and neutron reflectometry, can be realized to clarify the crystal and magnetic structures of advanced materials in different length scales ranging from atomic-scale to nano-scale. Given the fact that the physical and chemical properties of advanced materials, e.g. energy materials and functional materials, are intimately related to their microstructures, the successful application of various neutron scattering methods is not only significant in the understanding of structural-property relationship of these materials but also important in optimizing their physical and chemical performances.

This special issue contains eight papers, in which one perspective, four articles and three reviews are included. Among them, three papers focus on exploring the structural properties of electrode materials in Li- and Na-ion batteries via neutron diffraction, one is related to the spatiotemporal study of molecular clusters using different types of neutron scattering methods, one is related to the synthesis and characterization of organic proton conducting salts, one is related to the study on abnormal thermal expansion of material structure by neutron diffraction, one is related to the application of neutron diffraction in solid electrolyte and one is related to the investigation on organic photovoltaic materials via neutron scattering. We would like to express our sincere thanks to all the authors for their submission of such interesting works to this special issue. A brief summary of these eight papers is provided as follows:

In perspective “Spatiotemporal studies of molecular clusters with neutron scattering methodology”, the recent progresses in spatiotemporal studies of molecular clusters based materials by using different types of neutron scattering methodologies are summarized, mainly covering the structural characterizations and dynamics behavior explorations of molecular clusters systems. The neutron scattering can play an important role in understanding the complicated structures of molecular clusters systems as well as hierarchical dynamics behaviors at broad spatiotemporal scales.

In article “Neutron diffraction study on anomalous thermal expansion of CrB₂”, neutron powder diffraction experiments are conducted as a function of temperature on a hexagonal diboride CrB₂, revealing the anisotropic thermal expansion between the basal plane and c direction. Apparently, neutron diffraction can act as a powerful tool to investigate the thermal expansion and lattice evolution of materials.

In article “Alkali and alkaline ions co-substitution of P2 sodium layered oxides for sodium ion batteries”, a research progress about P2 sodium layered oxide is highlighted. By co-substitution with both Li and Mg, a modified P2-type cathode material is synthesized for sodium ion batteries. The co-substituted NiMn-based layered oxide exhibits an enhanced cycling performance. This research reveals the synergetic effects of alkali and alkaline ions substitutions in layered cathode materials, which is helpful in developing high energy density Na-ion batteries in the future.

In article “Solvent-free mechanochemical synthesis of organic proton conducting salts incorporating imidazole and dicarboxylic acids”, the imidazole-succinic acid and imidazole-glutaric acid compounds are synthesized by solventless mechanochemical synthesis method instead of conventional solution method. The compounds exhibit different electric conducting behavior and activation energies E_a. Besides, the crystal structure and phase evolution of compounds are investigated, evidencing the advantages of synthesis approach for preparing this class of materials.

In article “Structural insights into lithium-deficient type Li-rich layered oxide for high-performance cathode”, a series of lithium-deficient type Li-rich layered oxide with the chemical formula of Li_1.2–xNi_0.14Co_0.14Mn_0.53O₂ are successfully synthesized. The relationship between crystal structure and electrochemical properties of this material system is illustrated by applying series of advanced characterization methods. It is concluded that the lithium-deficient induced nickel migration and oxygen vacancy play a significant role in improving the electrochemical performances.

In review “Application of neutron scattering in organic photovoltaic materials”, few neutron scattering techniques, including neutron reflectivity, small angle neutron scattering, grazing incidence small angle neutron scattering and quasi-elastic neutron scattering, are introduced and the applications of these techniques in studying organic photovoltaic materials are reviewed. Furthermore, this review envisages that more neutron scattering techniques will be applied to the investigation of organic photovoltaic materials in the future.

In review “Exploring the structural properties of cathode and anode materials in Li-ion battery via neutron diffraction technique”, a comprehensive overview about the characteristics and advantages of neutron is introduced. From the aspects of structural details and structural evolution for both cathode and anode materials in Li-ion battery, the key role of neutron diffraction technique in structural characterization is demonstrated in great detail. In addition, the prospects for further applications of neutron diffraction technique are put forward.

In review “Neutron diffraction for revealing the structures and ionic transport mechanisms of antiperovskite solid electrolytes”, the progress of neutron diffraction in analyzing the structure-function relationships of antiperovskite solid-state electrolytes, involving the ionic transport pathway, defect chemistry, anion disorder and lattice dynamics, is introduced and summarized. Moreover, the possible future directions for the application of neutron diffraction in exploring antiperovskite solid-state electrolytes are discussed.