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Highlights: The lithium-ion conduction mechanism of organic-inorganic composite solid electrolytes (OICSEs) is thoroughly conducted and concluded from the microscopic perspective based on filler content, type, and system. The classic inorganic filler types, including inert and active fillers, are categorized with special emphasis on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs. Advanced characterization techniques for OICSEs are discussed, and the challenges and prospects for developing superior all-solid-state lithium batteries are highlighted. 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. [ABSTRACT FROM AUTHOR]

The interfacial instability of high‐nickel layered oxides severely plagues practical application of high‐energy quasi‐solid‐state lithium metal batteries (LMBs). Herein, a uniform and highly oxidation‐resistant polymer layer within inner Helmholtz plane is engineered by in situ polymerizing 1‐vinyl‐3‐ethylimidazolium (VEIM) cations preferentially adsorbed on LiNi0.83Co0.11Mn0.06O2 (NCM83) surface, inducing the formation of anion‐derived cathode electrolyte interphase with fast interfacial kinetics. Meanwhile, the copolymerization of [VEIM][BF4] and vinyl ethylene carbonate (VEC) endows P(VEC‐IL) copolymer with the positively‐charged imidazolium moieties, providing positive electric fields to facilitate Li+ transport and desolvation process. Consequently, the Li||NCM83 cells with a cut‐off voltage up to 4.5 V exhibit excellent reversible capacity of 130 mAh g−1 after 1000 cycles at 25 °C and considerable discharge capacity of 134 mAh g−1 without capacity decay after 100 cycles at −20 °C. This work provides deep understanding on tailoring electric double layer by cation specific adsorption for high‐voltage quasi‐solid‐state LMBs. [ABSTRACT FROM AUTHOR]

Quasi‐solid‐state lithium metal batteries (QSSLMBs) necessitate stable electro‐electrolyte interfaces to ensure reliable stationary power supply, thereby placing significant emphasis on the development of polymer electrolytes with high and uniform conductivity. However, while preparing the polymer electrolytes, the uncontrolled radical polymerization process of polymer electrolytes often leads to localized phase agglomeration, resulting in inhomogeneous physiochemical properties. In this study, a method is proposed to regulate the micro‐phase structure, aiming to substantially enhance the homogeneity of physiochemical properties, specifically the ionic conductivity, through the optimization of organic monomer polymerization behavior. This proposed polymer electrolyte determines enhanced reaction kinetics and reactivity at the interfaces, thereby effectively regulating the Li plating/stripping behavior and mitigating dendrite formation. The Li||Li symmetrical cell employing the proposed polymer electrolyte demonstrates exceptional cyclic durability, surpassing 1000 h at 0.2 mA cm−2. Additionally, the QSSLMBs employing high‐voltage LiCoO2 as the cathode exhibit remarkable improvements in electrochemical performance, particularly in terms of cycling stability. The insights derived from this research suggest that the regulation of micro‐phase structure in polymer electrolytes represents a promising strategy to enhance the practicability of QSSLMBs. [ABSTRACT FROM AUTHOR]

The Li7La3Zr2O12-based garnet (LLZO-BG) electrolyte has the advantage of strong thermal stability and can, therefore, avoid the flammability problem of organic electrolyte solutions. However, the solid-state lithium battery with LLZO-BG electrolyte has a much larger electrochemical resistance and poorer performance than the battery with an organic electrolyte solution, which is mainly related to the electrolyte/electrode interface. From the perspective of the LLZO-BG/Li interface, this review explores several interrelated interfacial issues, including the air instability of LLZO-BG, poor LLZO-BG/Li interfacial contact, easily generated lithium dendrite and the instability of LLZO-BG with the Li anode. We elaborate on the forming mechanisms, affecting factors and measures for improving these issues, and prospects for the future research directions of the LLZO-BG/Li interface. This review can provide new ideas for producing a solid-state lithium battery with high safety and high energy density. [ABSTRACT FROM AUTHOR]

The interfacial instability of high-nickel layered oxides severely plagues practical application of high-energy quasi-solid-state lithium metal batteries (LMBs). Herein, a uniform and highly oxidation-resistant polymer layer within inner Helmholtz plane is engineered by in situ polymerizing 1-vinyl-3-ethylimidazolium (VEIM) cations preferentially adsorbed on LiNi 0.83 Co 0.11 Mn 0.06 O 2 (NCM83) surface, inducing the formation of anion-derived cathode electrolyte interphase with fast interfacial kinetics. Meanwhile, the copolymerization of [VEIM][BF 4 ] and vinyl ethylene carbonate (VEC) endows P(VEC-IL) copolymer with the positively-charged imidazolium moieties, providing positive electric fields to facilitate Li + transport and desolvation process. Consequently, the Li||NCM83 cells with a cut-off voltage up to 4.5 V exhibit excellent reversible capacity of 130 mAh g -1 after 1000 cycles at 25 °C and considerable discharge capacity of 134 mAh g -1 without capacity decay after 100 cycles at -20 °C. This work provides deep understanding on tailoring electric double layer by cation specific adsorption for high-voltage quasi-solid-state LMBs., (© 2024 Wiley-VCH GmbH.)