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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]

• A novel poly (vinyl ethylene carbonate)-based dual-salt gel polymer electrolyte is developed by in-situ polymerization technology. • Stable interfacial layer is formed on electrodes by the synergistic effect of LiTFSI and LiBOB. • Li||Li symmetric and high-voltage Li||LiCoO 2 cells with DS-GPE exhibit superior electrochemical performances. Rechargeable lithium metal batteries (LMBs) have been regarded as one of the most promising next-generation energy-storage systems due to their high theoretical energy density. However, the practical application of LMBs is greatly impeded by poor high-voltage tolerance and safety concerns originated from flammable organic carbonate-based liquid electrolytes. Herein, a novel dual-salt gel polymer electrolyte (DS-GPE) is prepared via in situ polymerization of vinyl ethylene carbonate (VEC) and pentaerythritol tetra acrylate (PETEA) monomers in a poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) porous structure. The newly developed DS-GPE shows high ionic conductivity (6.9 mS cm−1) at room temperature, adequate Li+ transference number (t Li + = 0.512), outstanding oxidative resistance (5.3 V vs. Li/Li+) and favorable interfacial compatibility. Stable interfacial layers are rich in B-, F-, components on both the Li metal anode and high-voltage LiCoO 2 cathode, realizing excellent cycling stability in Li||Li symmetrical cells, and a capacity retention of 83.42% over 100 cycles with average Coulombic efficiency of 99.86% in Li||LiCoO 2 cell. [ABSTRACT FROM AUTHOR]

[Display omitted] • After the addition of flyash, Li+ transference number increases from 0.21 to 0.37. • The reason for mitigating free-TFSI– anions oxidative decomposition was revealed. • These cells present stable extrinsic-interfaces and excellent cycling performance. Satisfactory electrochemical stability of extrinsic-interfaces between electrodes and electrolyte is the prerequisite for the safe and durable applications of all-solid-state Lithium batteries (ALBs). Unfortunately, the oxidative decomposition of anions from Li-salt at the extrinsic-interfaces of cathode side leads to the electrochemical instability during charge process. Here, a novel composite polymer electrolyte (CPE) containing flyash-treated (FA) submicro/micron particles and poly(ethylene oxide) (PEO) matrix is reported. After the addition of FA filler, Li+ transference number increases from 0.21 to 0.37 and electrochemical stability window reaches 5.2 V. FA as filler can efficiently immobilize (trifluoromethanesulfonyl) imide (TFSI–) anions and mitigate their irreversible oxidative decomposition at the extrinsic-interface of cathode||CPE due to the internal binding interaction between TFSI– anions and FA particles. ALBs using CPE with FA can not only provide stable extrinsic-interfaces for uniform Li deposition, but also tolerate strong electrochemical polarization with excellent cycling performance. [ABSTRACT FROM AUTHOR]

The Li/Li symmetric cell with SbF 3 -modified Li as electrodes can achieve stable cycling over 400h at high current density of 3.0 mA cm−2 for fixed areal capacity of 3.0 mAh cm−2 and realize dendrite-free surface state. [Display omitted] • An artificial Li 3 Sb/LiF biphasic hybrid SEI layer was successfully constructed. • This biphasic hybrid SEI layer can effectively regulate Li ion depositing behavior. • The Li/Li symmetric cells with SF-Li anodes exhibit extended cycling lifespan. • The LMBs with SF-Li anodes deliver superior cycling performance and high CE. Lithium (Li) metal has been proposed as the most promising anode for secondary lithium batteries with high energy density due to its considerable theoretical capacity (3860 mAh g−1) and lowest electrochemical potential (-3.04 V vs standard hydrogen electrode). However, the uncontrollable dendrite Li issues over repeated plating/stripping process results in huge volume change, low Coulombic efficiencies (CEs), and poor cycling performance. Here, a solid electrolyte interphase (SEI) layer mainly consisting of biphasic hybrid Li 3 Sb and LiF has been successfully in situ constructed on Li surface by spontaneous chemical reaction between Li and SbF 3. The modified SEI can induce Li ions depositing on the linked-particle layer resulting from the relative low lithium diffusion coefficient of SEI layer component. The Li/Li symmetric cells with SbF 3 -modified Li (SF-Li) anodes show stable cycling over 400 h at 3.0 mA cm−2 for 3.0 mAh cm−2. The Li-S batteries with SF-Li anodes and ether-based electrolyte can achieve steady long-term cycling performance and high CEs. Particularly, the high voltage LiCoO 2 (LCO)/Li batteries with SF-Li anodes and carbonate-based electrolyte also deliver excellent electrochemical properties even at harsh conditions. This work offers a new strategy to regulate Li ion deposition and benefits for the further development of safe Li metal batteries (LMBs). [ABSTRACT FROM AUTHOR]