The development of safe, reliable, yet economical energy storage has been reemphasized with recent incidents involving the explosion and subsequent recall of lithium‐ion batteries. The organic liquid electrolyte used in the conventional lithium‐ion battery can potentially act as a fuel for combustion in a thermal‐runaway reaction, and hence an alternative with a significantly reduced flammability must be sought. All‐solid‐state batteries have the potential to meet safety and reliability requirements with the possibility of increasing the volumetric energy density of the system, making these a promising candidate for the development of the next generation of energy storage. Moreover, the sodium‐ion battery exhibits a better cost‐efficiency without significantly compromising the energy density, making the combination of the sodium chemistry with the solid electrolyte an attractive choice for safe and economical energy storage. Here, a general background on the recent development of ceramic and glass‐ceramic sodium‐ion‐conducting electrolytes is provided with regard to oxide‐, sulfide‐, and hydride‐based electrolytes. The ionic conductivity, chemical stability, and mechanical properties of the sodium‐based solid electrolyte are discussed, which is followed by a perspective on future developments in the field.

This article introduces a new type of ‘lithium-excess Li1+xFe1−xPO4’ cathode material for lithium rechargeable batteries.

All-solid-state batteries are considered as one of the attractive alternatives to conventional lithium-ion batteries, due to their intrinsic safe properties benefiting from the use of non-flammable solid electrolytes in ASSBs. However, one of the issues in employing the solid-state electrolyte is the sluggish ion transport kinetics arising from the chemical and physical instability of the interfaces among solid components including electrode material, electrolyte and additive agents. In this work, we investigate the stability of the interface between carbon conductive agents and Li10GeP2S12 in a composite cathode and its effect on the electrochemical performance of ASSBs. It is found that the inclusion of various carbon conductive agents in composite cathode leads to inferior kinetic performance of the cathode despite expectedly enhanced electrical conductivity of the composite. We observe that the poor kinetic performance is attributed to a large interfacial impedance which is gradually developed upon the inclusions of the various carbon conductive agents regardless of their physical differences. The analysis through X-ray Photoelectron Spectroscopy suggests that the carbon additives in the composite cathode stimulate the electrochemical decomposition of LGPS electrolyte degrading its surface during cycling, indicating the large interfacial resistance stems from the undesirable decomposition of the electrolyte at the interface.

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