The experimental method is the best approach to characterize the actual packing of spheres, but it is very troublesome to describe the random packing of spheres. Generally, it can only be used to simulate the packing of equal-diameter spheres, while the packing of non-equal-diameter spheres are more difficult, sometimes impossible. In this work, we have successfully investigated the problem of random packing of non-equiaxed ellipsoid by dynamic light scattering and electrochemical impedance spectroscopy. Moreover, we have successfully used the conductive NaTi2(PO4)3 (NTP) nanoparticles to verify the random packing of non-equiaxed ellipsoids by dynamic light scattering and electrochemical impedance spectroscopy. The results imply that the packing density is the larger, and the conductivity is the higher. Additionally, the wider size-distribution is helpful for increasing packing density. This method avoids the puzzling consideration of friction, particle shape and size, material density, the geometry of container and the initial state. Therefore, this divergent thinking of utilizing the conductive materials to research the random packing of non-equiaxed ellipsoids may be worth considering for the study of the close packing of other materials.

All-solid-state sodium-ion batteries (SIBs) possess the advantages of rich resources, low price, and high security, which are one of the best alternatives for large-scale energy storage systems in the future. Also, the chalcogenide solid electrolytes (CSEs) of SIBs have the characteristics of excellent room-temperature ionic conductivity (10⁻³-10⁻² S cm⁻¹), low activation energy (<0.6 eV), easy cold-pressing consolidation, etc. Hence, CSEs have become a very active area of all-solid-state SIB research in recent years. In this review, the modification methods and implementation technologies of CSEs are summarized, and the structure and electrochemical performance of the CSEs are discussed. Furthermore, the auxiliary function of first-principle calculations for modification is introduced. Ultimately, we describe the challenges regarding CSEs and propose some strategic suggestions.