Halide perovskite (HP) nanocrystals (NCs) have recently shown great potential for X-ray detection and imaging. However, the practical application is still a long way to go with lots of technical requirements waiting to be fulfilled, including structure optimization, stability enhancement, and cost reduction. A design principle in this beginning stage is urgently needed but still lacking. Herein, with an "emitter-in-matrix" principle refined from commercial scintillators, CsPbBr3@Cs4PbBr6 with emissive CsPbBr3 NCs embedded inside solid-state Cs4PbBr6 host is brought to X-ray sensing and imaging. The Cs4PbBr6 matrix not only enhances the attenuation of X-rays but also dramatically improves the stability of CsPbBr3 NCs. A favorable optical design with the Cs4PbBr6 matrix being transparent to the emission from CsPbBr3 NCs enables efficient light output. As a result, stable and sensitive scintillation response to X-ray signals is demonstrated with superior linearity and ultrahigh time resolution.In order to show the huge potential for practical application, X-ray imaging using a large-area film (360 mm×240 mm) by blade-coating technique is carried out to obtain a high-quality image of human eye-invisible interior structures. In addition to the above advantages in optics, CsPbBr3@Cs4PbBr6 also enjoys facile solution synthesis with large scalability, excellent repeatability and low cost.

Li-ion-conducting chloride solid electrolytes receive considerable attention due to their physicochemical characteristics such as high ionic conductivity, deformability and oxidative stability. However, the raw materials are expensive, and large-scale use of this class of inorganic superionic conductors seems unlikely. Here, a cost-effective chloride solid electrolyte, Li2ZrCl6, is reported. Its raw materials are several orders of magnitude cheaper than those for the state-of-the-art chloride solid electrolytes, but high ionic conductivity (0.81 mS cm–1 at room temperature), deformability, and compatibility with 4V-class cathodes are still simultaneously achieved in Li2ZrCl6. Moreover, Li2ZrCl6 demonstrates a humidity tolerance with no sign of moisture uptake or conductivity degradation after exposure to an atmosphere with 5% relative humidity. By combining Li2ZrCl6 with the Li-In anode and the single-crystal LiNi0.8Mn0.1Co0.1O2 cathode, we report a room-temperature all-solid-state cell with a stable specific capacity of about 150 mAh g–1 for 200 cycles at 200 mA g–1.