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Solid-state lithium metal batteries (SSLBs) using inorganic solid-state electrolytes (SSEs) have attracted extensive scientific and commercial interest owing to their potential to provide higher energy density and safety than conventional Li-ion batteries. These batteries are subject to external pressure during both their manufacturing processes (fabrication pressure) and their operation (stack pressure). This pressure not only affects the intrinsic properties of both the electrolytes (such as ionic conductivity and electrochemical voltage window) and the electrodes (such as ion transport and structural variation) but also determines the cyclability and safety of the whole battery. Hence, understanding the effect of pressure is essential when designing high-performance SSLBs. This Review aims to elucidate the coupling between external pressure and electrochemistry in these batteries. We summarize the effects of external pressure on SSEs and electrodes, and on the interfaces between the components. We analyse the overall electrochemical performance and safety of the batteries under external pressure. Finally, we clarify the dominant challenges in achieving pressure-proof and low-pressure SSLBs, laying out a perspective for future breakthroughs.

The high energy density and cost-effectiveness of chloride-ion batteries (CIBs) make them promising alternatives to lithium-ion batteries. However, the development of CIBs is greatly restricted by the lack of compatible electrolytes to support cost-effective anodes. Herein, we present a rationally designed solid polycationic electrolyte (SPE) to enable room-temperature chloride-ion batteries utilizing aluminum (Al) metal as an anode. This SPE endows the CIB configuration with improved air stability and safety (i.e. free of flammability and liquid leakage). A high ionic conductivity (1.3×10-2 S cm-1 at 25 °C) has been achieved by the well-tailored solvation structure of the SPE. Meanwhile, the solid polycationic electrolyte ensures stable electrodes|electrolyte interfaces, which effectively inhibit the growth of dendrites on the Al anodes and degradation of the FeOCl cathodes. The Al|SPE|FeOCl chloride-ion batteries showcased a high discharge capacity around 250 mAh g-1 (based on the cathodes) and extended lifespan. Our electrolyte design opens a new avenue for developing low-cost chloride-ion batteries.

The exploration of cathode and anode materials that enable reversible storage of mono and multivalent cations has driven extensive research on organic compounds. In this regard, polyimide (PI)-based electrodes have emerged as a promising avenue for the development of post-lithium energy storage systems. This review article provides a comprehensive summary of the syntheses, characterizations, and applications of PI compounds as electrode materials capable of hosting a wide range of cations. Furthermore, the review also delves into the advancements in PI based solid state batteries, PI-based separators, current collectors, and their effectiveness as polymeric binders. By highlighting the key findings in these areas, this review aims at contributing to the understanding and advancement of PI-based structures paving the way for the next generation of energy storage systems.