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Sulfide‐based superionic conductors with high ionic conductivity have been explored as candidates for solid‐state Li batteries. However, moisture hypersensitivity has made their manufacture complicated and costly and also impeded applications in batteries. Now, a sulfide‐based superionic conductor Li4Cu8Ge3S12 with superior stability was developed based on the hard/soft acid–base theory. The compound is stable in both moist air and aqueous LiOH aqueous solution. The electrochemical stability window was up to 1.5 V. An ionic conductivity of 0.9×10−4 S cm with low activation energy of 0.33 eV was achieved without any optimization. The material features a rigid Cu‐Ge‐S open framework that increases its stability. Meanwhile, the weak bonding between Li+ and the framework promotes ionic conductivity. This work provides a structural configuration in which weak Li bonding in the rigid framework promotes an environment for highly conductive and stable solid‐state electrolytes. [ABSTRACT FROM AUTHOR]

Sulfide‐based superionic conductors with high ionic conductivity have been explored as candidates for solid‐state Li batteries. However, moisture hypersensitivity has made their manufacture complicated and costly and also impeded applications in batteries. Now, a sulfide‐based superionic conductor Li4Cu8Ge3S12 with superior stability was developed based on the hard/soft acid–base theory. The compound is stable in both moist air and aqueous LiOH aqueous solution. The electrochemical stability window was up to 1.5 V. An ionic conductivity of 0.9×10−4 S cm with low activation energy of 0.33 eV was achieved without any optimization. The material features a rigid Cu‐Ge‐S open framework that increases its stability. Meanwhile, the weak bonding between Li+ and the framework promotes ionic conductivity. This work provides a structural configuration in which weak Li bonding in the rigid framework promotes an environment for highly conductive and stable solid‐state electrolytes. [ABSTRACT FROM AUTHOR]

Compared with lithium-ion batteries, sodium-ion batteries possess the advantages of low cost and high energy density. The research and development of the positive, negative and electrolyte materials of sodium-ion batteries is of great significance to develop sodium-ion energy storage devices. The sodium superionic conductor (NASICON) with a stoichiometric ratio of Na 3 Sc 2 P 3 O 12 (NSP) has a variety of crystal types, namely α-, β- and γ-phase. Different crystal structures exhibit different ion transport characteristics, resulting in the varied ionic conductivity and other electrochemical performance. The effect of different crystalline-type Na 3 Sc 2 P 3 O 12 (α-Na 3 Sc 2 P 3 O 12 , β-Na 3.5 Sc 2 P 2.5 Si 0.5 O 12 and γ-Na 4 Sc 2 P 2 SiO 12) fillers on gel polymer electrolytes (GPE) was investigated in detail. Due to the difference in the adsorption capacity of the gel electrolyte added three types of crystalline-type fillers and the difference in the conductivity of fillers, the composite gel electrolytes exhibited various performances. The optimal gel electrolyte with 7 ​% γ-Na 4 Sc 2 P 2 SiO 12 filler delivers the optimal conductivity as high as 2.783 ​× ​10−3 ​S ​cm−1. The optimal performance of Na 3 V 2 (PO 4) 3 /C| GPE |Na cell shows that the first discharge specific capacity was 92.3 mAh g−1 with a capacity retention rate of 98.18% after 100 cycles. Different crystalline-type sodium conductive filler (α-Na 3 Sc 2 P 3 O 12 , β-Na 3.5 Sc 2 P 2.5 Si 0.5 O 12 and γ-Na 4 Sc 2 P 2 SiO 12) modified GPEs membranes with enhanced ionic conductivity were fabricated and the application performances in sodium ions batteries (SIBs) were demonstrated. [Display omitted] • Sodium conductive Na 3 Sc 2 P 3 O 12 filler with three types of crystal phases modified GPEs were fabricated. • Ionic conductivity of GPEs was enhanced with the presence of Na 3 Sc 2 P 3 O 12 filler. • Na 3 Sc 2 P 3 O 12 filler decreased the crystallinity and enlarged the porosity of GPEs. • GPEs membranes delivered competitive electrochemical performances applied in SIBs. [ABSTRACT FROM AUTHOR]