Previously, α-Fe2O3 nanocrystals are recognized as anode materials owing to their high capacity and multiple properties. Now, this work provides high-voltage α-Fe2O3 nanoceramics cathodes fabricated by the solvothermal and calcination processes for sodium-ion batteries (SIBs). Then, their structure and electrical conductivity were investigated by the first-principles calculations. Also, the SIB with the α-Fe2O3 nanoceramics cathode exhibits a high initial charge-specific capacity of 692.5 mA h g-1 from 2.0 to 4.5 V at a current density of 25 mA g-1. After 800 cycles, the discharge capacity is still 201.8 mA h g-1, well exceeding the one associated with the present-state high-voltage SIB. Furthermore, the effect of the porous structure of the α-Fe2O3 nanoceramics on sodium ion transport and cyclability is investigated. This reveals that α-Fe2O3 nanoceramics will be a remarkably promising low-cost and pollution-free high-voltage cathode candidate for high-voltage SIBs.

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NaTi2(PO4)3 (NTP), a well-known anode material, could be used as a solid wide-band gap electrolyte. Herein, a novel solid-state sodium-ion battery (SSIB) with the thickness of electrolyte up to the millimeter level is proposed. The results of the difference in charge density investigated by the first-principles calculations imply that using the NTP nanocrystals as electrolytes to transport sodium ions is feasible. Moreover, the SSIB exhibits a high initial discharge capacity of 3250 mAh g-1 at the current density of 50 mA g-1. As compared with other previously reported SSIBs, our results are better than those reported and suggest that the NTP nanocrystals have potential application in SSIBs as solid electrolytes.

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Human skin, with beneficial elasticity and reparability, could sense the changes of the external environment through different receptors. Imitating these mechanical properties and perception of bionic skin with power supply function is an enormous challenge in the field of Internet of things and artificial intelligence. Herein, the neural signal transmission of human skin is imitated to create a smart self-powered bionic skin fragment integrating skin and power supply functions. Unlike the traditional bionic skin in essence, it can intelligently perceive the outside world by using anion-selective and cation-selective gels to control exchangeable anions and cations to realize the change of resting current and action current, and it can maintain the relatively stable self-powered current of 0.5 µA for nearly 2.2 h. Moreover, its mechanisms of current and voltage changes are systematically investigated. These results reveal that it can be applied to the synchronous transmission of signals for the next-generation neurologically integrated soft engineering systems such as bionic sensors, or prosthetic devices in hybrids of living and nonliving systems.

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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.

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All-solid-state sodium-ion battery (ASSIB) is a promising new energy storage device due to the excellent thermal stability, low flammability, high impermeability and nonvolatility, as well as riskless fire and explosion properties. The solid electrolyte plays a core role in the ASSIBs to determine their electrochemical performance. Herein, close attention is paid to effective approaches to improve the performance of solid electrolytes, including ion doping and substitution, composite method, coating method, crystal transformation method, ceramization and vitrification, etc. In particular, electrochemical window, ionic conductivity, electrochemical stability, and structural stability are also reviewed. The future development of solid electrolytes and the possible directions for improving the properties of the ASSIBs in practical applications are also prospects. This review will guide the development of solid electrolytes for the ASSIBs in future.

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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.@en