, 0.7Li(CB 9 H 10)−0.3Li(CB 11 H 12), 6.7 mS cm −1), [11,12] and halides (e.g., Li 3 YX 6 [X = Cl, Br], 0.51-1.7 mS cm −1). [13,14] Thus far, oxide and sulfide SEs have been the most commonly investigated candidates. However, their pros and cons counteract each other. Oxide SEs possess high intrinsic electrochemical oxidation stabilities and relatively acceptable chemical stabilities; however, owing to their brittle nature, it is difficult to integrate them in devices. [3,10,15-17] On the other hand, the most important advantage of sulfide SEs, that is, mechanical deformability, which enables scalable cold-pressing-based fabrication protocols, is offset by their poor (electro)chemical stabilities. [3,16,18-20] On exposing sulfide SEs to humid air, the evolution of toxic H 2 S gases occurs. [21-26] Moreover, sulfide SEs exhibit oxidative decomposition at <3 V (vs Li/Li +) and are also incompatible with conventional layered LiMO 2 (M = Ni, Co, Mn, and Al) cathodes. [16,19,27] This issue can be alleviated by using protective coatings, such as LiNbO 3 and Li 3−x B 1−x C x O 3 ; [7,27] however, this constitutes additional processing costs. Furthermore, the oxidative decomposition of sulfide SEs at the surface of conductive carbon additives is unavoidable. [28-31] Recently, through reinvestigations on halide SEs, several compounds exhibiting Li + conductivities exceeding 10 −4 S cm −1 have been identified. [13,32−36] Asano and coworkers reported that trigonal Li 3 YCl 6 and monoclinic Li 3 YBr 6 showed high Li + Owing to the combined advantages of sulfide and oxide solid electrolytes (SEs), that is, mechanical sinterability and excellent (electro)chemical stability, recently emerging halide SEs such as Li 3 YCl 6 are considered to be a game changer for the development of all-solid-state batteries. However, the use of expensive central metals hinders their practical applicability. Herein, a new halide superionic conductors are reported that are free of rare-earth metals: hexagonal close-packed (hcp) Li 2 ZrCl 6 and Fe 3+-substituted Li 2 ZrCl 6 , derived via a mechanochemical method. Conventional heat treatment yields cubic close-packed monoclinic Li 2 ZrCl 6 with a low Li + conductivity of 5.7 × 10 −6 S cm −1 at 30 °C. In contrast, hcp Li 2 ZrCl 6 with a high Li + conductivity of 4.0 × 10 −4 S cm −1 is derived via ball-milling. More importantly, the aliovalent substitution of Li 2 ZrCl 6 with Fe 3+ , which is probed by complementary analyses using X-ray diffraction, pair distribution function, X-ray absorption spectroscopy, and Raman spectroscopy measurements, drastically enhances the Li + conductivity up to ≈1 mS cm −1 for Li 2.25 Zr 0.75 Fe 0.25 Cl 6. The superior interfacial stability when using Li 2+x Zr 1−x Fe x Cl 6 , as compared to that when using conventional Li 6 PS 5 Cl, is proved. Furthermore, an excellent electrochemical performance of the all-solid-state batteries is achieved via the combination of Li 2 ZrCl 6 and single-crystalline LiNi 0.88 Co 0.11 Al 0.01 O 2 .

No abstract

No abstract

Solid electrolytes (SEs) are promising candidates for enhancing the energy density and safety of conventional lithium-ion batteries. Recently, lithium thioantimonate iodide argyrodites have been regarded as promising SEs because of their high ionic conductivities and air-stability. In this study, we utilized highenergy ball milling to synthesize Ge-substituted thioantimonate argyrodites and achieved an ionic conductivity of 16.1 mS cm −1 for Li 6.5 Sb 0.5 Ge 0.5 S 5 I, which is the highest value among the reported cold-pressed SE pellets. First-principles calculations reveal that concerted Li-ion migrations through the inter-cage paths substantially improve the ionic conductivity. Li 6.5 Sb 0.5 Ge 0.5 S 5 I shows good compatibility with LiNi 0.5 Co 0.2 Mn 0.3 O 2 -based all-solid-state batteries (ASSBs) after applying Li 3 YCl 6 as a catholyte, which exhibits a high discharge capacity of 164 mAh g −1 and good cycle stability. Ge-substituted thioantimonate argyrodites exhibit excellent air-stability, which facilitates reducing the synthesis and fabrication costs of ASSBs with hygroscopic P-based sulfide SEs. The superionic conductors with high air-stability reported in this study demonstrate substantial promise for the development of ASSBs.

No abstract

Owing to their high Li + conductivities, mechanical sinterability, and solution processability, sulfide Li argyrodites have attracted much attention as enablers in the development of highperformance all-solid-state batteries with practicability. However, solution-processable Li argyrodites have been developed only for a composition of Li 6 PS 5 X (X = Cl, Br, I) with insufficiently high Li + conductivities (∼10 −4 S cm −1 ). Herein, we report the highest Li + conductivity of 0.54 mS cm −1 at 30 °C (Li 6.5 P 0.5 Ge 0.5 S 5 I) for solution-processable iodine-based Li argyrodites. A comparative investigation of three iodine-based argyrodites of unsubstituted and Ge-and Sn-substituted solution-processed Li 6 PS 5 I with varied heat-treatment temperature elucidates the effect of microstructural evolution on Li + conductivity. Notably, local nanostructures consisting of argyrodite nanocrystallites in solution-processed Li 6.5 P 0.5 Ge 0.5 S 5 I have been directly captured by cryogenic transmission electron microscopy, which is a first for sulfide solid electrolyte materials. Specifically, the promising electrochemical performances of all-solid-state batteries at 30 °C employing LiCoO 2 electrodes tailored by the infiltration of Li 6.5 P 0.5 Ge 0.5 S 5 I−ethanol solutions are successfully demonstrated.

Considerable progress has been made in the conversion of carbon dioxide (CO2), which is highly thermodynamically stable, into liquid hydrocarbons using metal oxide/zeolite composite catalysts. Nevertheless, producing liquid hydrocarbons with a single catalyst without utilizing additional C–C coupling agents remains a formidable challenge. Herein, we report a bifunctional iron aluminum oxide (FeAlO x ) catalyst that directly converts CO2 into C5+ hydrocarbons with an overall selectivity of 77.0% and CO2 conversion of 20.2% at a H2/CO2 ratio of 1:1. Notably, the selectivity for linear α-olefins (LAOs) was 52.4%, accounting for 78.4% of the total C4+ olefins. At a high H2/CO2 ratio of 3:1, the yield of C5+ hydrocarbons was 19.7%. The concept of crystalline-/amorphous-structured active sites in the single FeAlO x catalyst was proposed. The reducible magnetite (Fe3O4) phase, which contains surface oxygen vacancies, facilitated the reverse-water–gas-shift (RWGS) reaction to form CO via CO2 hydrogenation, and subsequent C–C coupling over Hägg iron carbide afforded lower olefins (C2–C4 =). Long-chain LAOs were then formed on the surface of amorphous aluminum oxide (AlO x ) via the readsorption of C2–C4 =. In addition, the amorphous AlO x phase enhanced CO2 and H2 adsorption, which facilitated the formation of carbonate, bicarbonate, and formate species via the RWGS reaction and the subsequent formation of long-chain hydrocarbons via the Fischer–Tropsch reaction. The bifunctional FeAlO x catalyst showed excellent stability for up to 450 h on-stream, demonstrating its potential as a practical-scale catalyst for the conversion of CO2 into value-added liquid fuels and chemicals.

Designing highly conductive and (electro)chemical stable inorganic solid electrolytes using cost-effective materials is crucial for developing all-solid-state batteries. Here, we report halide nanocomposite solid electrolytes (HNSEs) ZrO2(-ACl)-A2ZrCl6 (A = Li or Na) that demonstrate improved ionic conductivities at 30 °C, from 0.40 to 1.3 mS cm−1 and from 0.011 to 0.11 mS cm−1 for Li+ and Na+, respectively, compared to A2ZrCl6, and improved compatibility with sulfide solid electrolytes. The mechanochemical method employing Li2O for the HNSEs synthesis enables the formation of nanostructured networks that promote interfacial superionic conduction. Via density functional theory calculations combined with synchrotron X-ray and 6Li nuclear magnetic resonance measurements and analyses, we demonstrate that interfacial oxygen-substituted compounds are responsible for the boosted interfacial conduction mechanism. Compared to state-of-the-art Li2ZrCl6, the fluorinated ZrO2−2Li2ZrCl5F HNSE shows improved high-voltage stability and interfacial compatibility with Li6PS5Cl and layered lithium transition metal oxide-based positive electrodes without detrimentally affecting Li+ conductivity. We also report the assembly and testing of a Li-In||LiNi0.88Co0.11Mn0.01O2 all-solid-state lab-scale cell operating at 30 °C and 70 MPa and capable of delivering a specific discharge of 115 mAh g−1 after almost 2000 cycles at 400 mA g−1.