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Solid/solid interface is the major challenge for high‐performance solid‐state batteries. Solid electrolytes (SEs) play a crucial role in the fabrication of effective interfaces in solid‐state batteries. Herein, the electrolyte distribution with varied particle sizes is tuned to construct solid‐state batteries with excellent performance at different operating temperatures. Solid‐state batteries with the configuration S/L (small‐sized SE in composite cathode and large‐sized SE in electrolyte layer) show the best performance at room temperature (168 mA h g−1 at 0.2 C, retention of 99%, 100 cycles) and −20 °C (89 mA h g−1 at 0.05 C), while the configuration S/S displays better performance at elevated temperature. The superior performance of S/L battery is associated with faster lithium‐ion dynamics due to the better solid/solid interface between active materials and electrolytes. Moreover, the inferior performance at 60 °C is caused by the formation of voids and cracks in the electrolyte layer during cycling. In contrast, the S/S battery delivers superior performance at elevated operating temperature because of the integrated structure. This work confirms that tailoring electrolyte size has significant effect on fabricating all‐climate solid‐state batteries. [ABSTRACT FROM AUTHOR]

A viscous feature is beneficial for a solid electrolyte with respect to assembling solid‐state batteries, which can change the solid‐solid contacts from point to face. Here, novel halide‐based deep eutectic solid electrolytes (DESEs) prepared by a facile ball milling method is reported. The mixture of halides triggers the deep eutectic phenomena by intermolecular interactions, leading to diverse morphologies and viscous statuses in terms of composition. Chemical‐ and micro‐structure analyses via the cryogenic technique reveal that the LiCl and LiF nanoparticles are dispersed in an amorphous halide matrix, which endow freely mobile ions for fast ion transport. The optimized DESE thus achieves low activation energy and high ionic conductivity of 16 mS cm−1 at room temperature, one of the highest values among various electrolytes so far. By integrating with the active materials to form a composite cathode, the viscous DESE yields a super‐dense composite pellet which possesses intensively enhanced ionic conductivity in contrast to those formed by the sulfide‐based electrolyte additives, demonstrating an attractive application prospect. [ABSTRACT FROM AUTHOR]

The severe parasitic interface reaction and dendrite growth retard the practical applications of all‐solid‐state (ASS) Na batteries with sulfide solid electrolytes (SEs). Here, a novel composite SE is proposed, with a high ionic conductivity, composed of Na3SbS4 (NSS) and oxysulfide glass. The study reveals that the P2S7‐aOa and PS4‐aOa units in oxysulfide play various roles: The former is deoxidized to release free O ions, which reacts with the anode via migrating to form oxides, favoring an improved interface stability. The latter is highly stable upon cycling, thereby maintaining an ion transport network. Meanwhile, NSS acts as a dendrite predator via reacting with penetrated Na. These advantages enable the resulting ASS Na battery with superior long‐term cycling performance at a high current density at room temperature, one of the best results so far. This discovery sheds light on innovative advanced SE materials through an oxysulfide‐based composite design. [ABSTRACT FROM AUTHOR]

All-solid-state (ASS) Na-S batteries are promising for a large-scale energy-storage system owing to numerous merits. However, the high conversion reaction barrier impedes their practical application. In this work, the basic mechanism on how Se catalyzes the conversion reaction in the Na-S batteries is unraveled. The sodiation/desodiation of Na-SeS2 nanobatteries are systematically evaluated via in situ transmission electron microscopy (in situ TEM) with a microheating device. The real-time analyses reveal an amorphous Na-SexSy intermediate phase appears during the direct conversion from SeS2 to Na2S, and a reverse reaction succeeds at 100 °C with a prior formation of Se. The absence of polysulfides and a much lower desodiation temperature in contrast to Na-S nanobatteries demonstrate that the Se incorporation significantly lowers the conversion reaction barrier. According to these findings, the ASS SeS2 batteries using a Na3SbS4 solid electrolyte (SE) are assembled using various SE:C ratios in the composite cathodes to investigate the effect of the ion and electron transport on the electrochemical properties, including the effective transport properties, MacMullin number, and the tortuosity factor. The obtained results in turn confirm the findings from the in situ TEM. These findings are applicable to optimize other S-based active materials and improve their utilization. [ABSTRACT FROM AUTHOR]

• A facile process is developed to prepare argyrodite electrolytes in large quantities. • The electrolyte Li 5.5 PS 4.5 Cl 1.5 achieves a high ionic conductivity of 9.03 mS/cm. • The SSBs deliver superior rate capability and cycling performance at RT and −20 ℃. Solid-state batteries (SSBs) employing sulfide electrolytes (SEs) are considered with poor rate capability and short cycling span life, especially towards the pristine nickel-rich cathode. The high cost, low conductivity, and compatibility are regarded as the major obstacles. In this work, chlorine-rich Li 5.5 PS 4.5 Cl 1.5 electrolyte with high conductivity (9.03 mS/cm) is synthesized via an easy scale-up route. The role of carbon in the cathode mixture is unraveled at room temperature (RT) and low temperature. SSBs using designed cathode without carbon deliver capacity retention of 82.4% after 10,000 cycles under 10C at room temperature and 97.0% after 200 cycles under 0.2C at −20 ℃. This research shows the potential of utilizing SEs to manufacture SSBs with high rates and long cyclability under different temperatures. [ABSTRACT FROM AUTHOR]

Li 6 PS 5 I electrolyte shows significant potential as solid electrolytes due to its low cost and high stability. However, the poor room temperature Li-ion conductivity (10−6 S/cm) limits its applications in solid-state batteries. This work aims to increase the conductivity of Li 6 PS 5 I by introducing LiCl in the structure using high-rotation mechanical milling. Structure analysis confirms that a minor dopant of Cl− can form a single-phase of Li 6 PS 5 Cl x I 1-x argyrodite electrolytes, while a large doping amount yields a mixture of the Li 6 PS 5 I and Li 6 PS 5 Cl phases. The modified electrolytes with "composition" Li 6 PS 5 Cl 0.7 I 0.3 show the highest room temperature Li-ion conductivity among the milled and sintered sample, 7.37 × 10−4 and 2.33 × 10−3 S/cm, both of which are much higher than the conductivity of pristine Li 6 PS 5 I. Solid-state batteries using the above solid electrolytes combined with LiNbO 3 -coated LiNi 0.7 Mn 0.2 Co 0.1 O 2 cathode and Li In anode display excellent electrochemical performances. The battery using annealed Li 6 PS 5 Cl 0.7 I 0.3 electrolyte delivers improved discharge capacities and extended cycling performances at different operating temperatures. This work provides an effective strategy to design high conductivity Li 6 PS 5 I-based solid electrolytes for solid-state batteries. • LiCl promote the Li-ion conductivity of Li 6 PS 5 I electrolytes. • Solid-state battery using Li 6 PS 5 Cl 0.7 I 0.3 electrolyte shows high capacity and good cycling performance. • In-situ EIS reveals the resistance evolution of solid-state batteries using Li 6 PS 5 Cl 0.7 I 0.3 electrolytes. [ABSTRACT FROM AUTHOR]