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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 Li3YCl6 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) Li2ZrCl6 and Fe3+‐substituted Li2ZrCl6, derived via a mechanochemical method. Conventional heat treatment yields cubic close‐packed monoclinic Li2ZrCl6 with a low Li+ conductivity of 5.7 × 10−6 S cm−1 at 30 °C. In contrast, hcp Li2ZrCl6 with a high Li+ conductivity of 4.0 × 10−4 S cm−1 is derived via ball‐milling. More importantly, the aliovalent substitution of Li2ZrCl6 with Fe3+, 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 Li2.25Zr0.75Fe0.25Cl6. The superior interfacial stability when using Li2+xZr1−xFexCl6, as compared to that when using conventional Li6PS5Cl, is proved. Furthermore, an excellent electrochemical performance of the all‐solid‐state batteries is achieved via the combination of Li2ZrCl6 and single‐crystalline LiNi0.88Co0.11Al0.01O2. [ABSTRACT FROM AUTHOR]

Potassium‐ion batteries (KIBs) are one of the potential candidates for large‐scale energy storage devices with low cost due to the abundance of potassium resources. However, the development of cathode materials with high capacity and structural stability has been a challenge due to the difficulties of intercalation of the large size of K‐ions into host materials. In this work, H2V3O8 (or V3O7⋅H2O) is reported as a new cathode material for KIBs. It shows reversible potassium‐intercalation behavior with the first discharge capacity of 168 mAh g−1 at 5 mA g−1 and an average discharge voltage of ∼2.5 V (vs. K/K+) in 0.5 M KPF6 in EC/DEC (1:1 v/v). The specific capacity increases up to 181 mAh g−1 for the third cycle and gradually decreases with 75% of the capacity retention after 100 cycles. The chemical formula of the potassiated phase is K1.77H2V3O8. However, scan‐rate dependent cyclic voltammetry and elemental analyses suggest that ∼28% of the capacity comes from the surface K ions on the H2V3O8 particles; thus, the bulk‐intercalated phase can be formulated as K1.27H2V3O8. The crystal structure is stable during the electrochemical cycling, keeping the structural water, confirming that H2V3O8 can be considered as one of the high‐capacity cathode materials for KIBs. [ABSTRACT FROM AUTHOR]

All-Solid-State Batteries: New Cost-Effective Halide Solid Electrolytes for All-Solid-State Batteries: Mechanochemically Prepared Fe3+-Substituted Li2ZrCl6 (Adv. Electrodes, halides, ionic conductivities, solid electrolytes, solid-state batteries Keywords: electrodes; halides; ionic conductivities; solid electrolytes; solid-state batteries EN electrodes halides ionic conductivities solid electrolytes solid-state batteries 1 1 1 03/27/21 20210325 NES 210325 In article number 2003190, Kyung-Wan Nam, Yoon Seok Jung and co-workers develop a new halide solid electrolyte, Fe SP 3+ sp -substituted Li SB 2 sb ZrCl SB 6 sb , that is mechanically sinterable, (electro)chemical-oxidation tolerant, and free of rare-earth metals. [Extracted from the article]

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 Li3YCl6 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) Li2ZrCl6 and Fe3+‐substituted Li2ZrCl6, derived via a mechanochemical method. Conventional heat treatment yields cubic close‐packed monoclinic Li2ZrCl6 with a low Li+ conductivity of 5.7 × 10−6 S cm−1 at 30 °C. In contrast, hcp Li2ZrCl6 with a high Li+ conductivity of 4.0 × 10−4 S cm−1 is derived via ball‐milling. More importantly, the aliovalent substitution of Li2ZrCl6 with Fe3+, 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 Li2.25Zr0.75Fe0.25Cl6. The superior interfacial stability when using Li2+xZr1−xFexCl6, as compared to that when using conventional Li6PS5Cl, is proved. Furthermore, an excellent electrochemical performance of the all‐solid‐state batteries is achieved via the combination of Li2ZrCl6 and single‐crystalline LiNi0.88Co0.11Al0.01O2. [ABSTRACT FROM AUTHOR]

This study demonstrates an organic electrolyte-based rechargeable zinc-ion battery (ZIB) using Prussian blue (PB) analogue potassium nickel hexacyanoferrate K 0.86 Ni[Fe(CN) 6 ] 0.954 (H 2 O) 0.766 (KNF-086) as the cathode material. KNF-086 is prepared via electrochemical extraction of potassium ions from K 1.51 Ni[Fe(CN) 6 ] 0.954 (H 2 O) 0.766 (KNF-151). The cell is composed of a KNF-086 cathode, a zinc metal anode, and a 0.5 M Zn(ClO 4 ) 2 acetonitrile electrolyte. This cell shows a reversible discharge capacity of 55.6 mAh g −1 at 0.2 C rate with the discharge voltage at 1.19 V (vs. Zn 2+ /Zn). As evidenced by Fourier electron density analysis with powder XRD data, the zinc-inserted phase is confirmed as Zn 0.32 K 0.86 Ni[Fe(CN) 6 ] 0.954 (H 2 O) 0.766 (ZKNF-086), and the position of the zinc ion in ZKNF-086 is revealed as the center of the large interstitial cavities of the cubic PB. Compared to KNF-086, ZKNF-086 exhibits a decreased unit cell parameter (0.9%) and volume (2.8%) while the interatomic distance of d (Fe-C) increased (from 1.84 to 1.98 Å), and the oxidation state of iron decreases from 3 to 2.23. The organic electrolyte system provides higher zinc cycling efficiency (>99.9%) than the aqueous system (ca. 80%). This result demonstrates an organic electrolyte-based ZIB, and offers a crucial basis for understanding the electrochemical intercalation chemistry of zinc ions in organic electrolytes. [ABSTRACT FROM AUTHOR]