To address the limitations of contemporary lithium-ion batteries, particularly their low energy density and safety concerns, all-solid-state lithium batteries equipped with solid-state electrolytes have been identified as an up-and-coming alternative. Among the various SEs, organic–inorganic composite solid electrolytes (OICSEs) that combine the advantages of both polymer and inorganic materials demonstrate promising potential for large-scale applications. However, OICSEs still face many challenges in practical applications, such as low ionic conductivity and poor interfacial stability, which severely limit their applications. This review provides a comprehensive overview of recent research advancements in OICSEs. Specifically, the influence of inorganic fillers on the main functional parameters of OICSEs, including ionic conductivity, Li⁺ transfer number, mechanical strength, electrochemical stability, electronic conductivity, and thermal stability are systematically discussed. The lithium-ion conduction mechanism of OICSE is thoroughly analyzed and concluded from the microscopic perspective. Besides, the classic inorganic filler types, including both inert and active fillers, are categorized with special emphasis on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs. Finally, the advanced characterization techniques relevant to OICSEs are summarized, and the challenges and perspectives on the future development of OICSEs are also highlighted for constructing superior ASSLBs.

Succinonitrile (SN)-based electrolytes are attractive due to their considerable ionic conductivity and high oxidative stability. However, the spontaneous chemical side-reactions between SN and Li-metal restrict the extensive applications of such electrolytes in next-generation advanced Li-metal batteries. Herein, we report a novel SN-based electrolyte SN–DLi–FEC which combines the dual-salt (lithium bis(trifluoromethane sulfonimide) (LiTFSI) and lithium difluoro(oxalato)borate (LiODFB)) and the fluoroethylene carbonate (FEC) additive. Compared with other SN-based electrolytes such as SN–SLi–FEC (single salt combined with FEC), SN–DLi–FEC can form a more stable and durable organic–inorganic composite SEI film rich in the B–F bond and LiF on the surface of the Li-metal anode. As a result, interfacial compatibility of the SN-based electrolytes and the Li-metal anode can be significantly enhanced. Moreover, SN–DLi–FEC shows high oxidation resistance, high ionic conductivity and good thermal stability. The LiCoO₂ (LCO)/Li battery equipped with SN–DLi–FEC exhibits excellent electrochemical performances at room temperature (RT) and high temperature, and high thermal safety. The novel SN-based electrolyte prepared in this work could be a promising candidate providing better reliability and safety for the development of Li-metal batteries.

Prussian blue analogues exhibit significant potential as positive electrode materials for sodium-ion batteries, particularly due to their three-dimensional cyanide-bridged frameworks which facilitate fast charging capabilities. However, the labile chemical bonds coordinated by transition metal ions and cyanide ligands often lead to structural instability, causing serious electrochemical degradations during cycling. Fundamentally understanding and controlling the local electronic structure to mitigate this instability remains challenging. Herein, we approach this problem by modulating the local electronic structure surrounding nitrogen-coordinated transition metal ions to create a uniform electron distribution within the Prussian blue analogues frameworks. The resulting uniform electronic structure enhances the reactivity of both nitrogen-coordinated and carbon-coordinated transition metals. More importantly, the reduction of electronic displacement through regulated coordination significantly improves the crystal structural stability, yielding a capacity retention of over 91% at 5 C after 1000 cycles. These findings provide insights into the local structural chemistry of Prussian blue analogues and offer guidance for the development of positive materials for sodium-ion batteries.