NASICON 타입 및 calcium vanadium bronze 물질의 칼슘이온 배터리용 양극소재로의 연구논문

Calcium ion batteries (CIBs), ab initio structure determination, X-ray diffraction, battery, cathodeNDoctordCollectio

Bilayered Ca0.28V2O5·H2O: High-Capacity Cathode Material for Rechargeable Ca-Ion Batteries and Its Charge Storage Mechanism

Despite the attractive theoretical benefits of calcium-ion batteries (CIBs) as post-lithium-ion batteries, only a limited number of host materials are known to reversibly intercalate calcium ions to date, and their intercalation mechanism is barely understood. Herein, we report bilayered Ca0.28V2O5·H2O as a high-capacity CIB cathode material. It exhibits a capacity of 142 mA h g-1 at ∼3.0 V vs Ca/Ca2+ and excellent cyclability. Ca0.28V2O5·H2O undergoes irreversible structural transformation to a two-fold superstructure during the first charge, which triggers its electrochemical activity from the subsequent cycling. Its intercalation mechanism is unique; upon charging, complete calcium extraction occurs from every two interlayers, maintaining only a fraction of calcium ions in the other interlayers; on discharge, calcium ions are irregularly inserted into the interlayers, resulting in stacking faults. This charge-discharge cycle is highly reversible. This work would be the first report that experimentally unveils the electrochemical calcium storage mechanism of an intercalation host material, providing valuable insights for developing high-performance CIB cathodes. © 2022 American Chemical Society.FALS

A sulfone-based crystalline organic electrolyte for 5 V solid-state potassium batteries

Solid-state potassium batteries are promising energy storage systems, but their wide use requires suitable solid electrolytes to ensure high ionic conductivity, electrochemical stability, and contacting ability with composite electrodes. For this purpose, this study introduces sulfone-based crystalline organic electrolytes (SCOEs) consisting of dimethyl sulfone (DMS) and potassium bis(fluorosulfonyl)imide (KFSI). One solid-state SCOE, KFSI/DMS 1:9 by mol, exhibits high ionic conductivity (4.0 x 10(-4) S cm(-1) at 25 C), oxidation stability (-5.8 V vs. K+/K-), and negligible flammability. Moreover, owing to its optimal melting point (94 C), the SCOE enables seamless contact with the composite electrodes through the melt-casting process, which has been challenging for other solid-state electrolytes. K|| KVPO4F cells filled with this SCOE show improved cycle performance (capacity retention 88.8% after 100 cycles vs. 77.6% after 74 cycles at 25 C) with high Coulombic efficiency (asymptotic value 99.6% vs. 92.0%) compared to cells with a conventional carbonate electrolyte. With these results, the developed SCOE paves the way to room-temperature operable, 5 V solid-state potassium batteries.FALS

Silver vanadium bronze, beta-Ag0.33V2O5: crystal-water-free high-capacity cathode material for rechargeable Ca-ion batteries

Calcium-ion batteries (CIBs) are getting increasing attention as post-lithium-ion batteries owing to their theoretical and potential advantages in terms of energy density and cost-effectiveness. However, most of the reported cathode materials suffer from low capacity or cyclability in dried nonaqueous electrolytes. So far, all of the materials with high capacity (>100 mA h g−1) contain crystal water, which was considered to be crucial to the structural stability, enabling facile Ca diffusion. Here, we report β-Ag0.33V2O5as a high-capacity cathode material for CIBs without crystal water. After the initial activation process, the material exhibited a capacity of 179 mA h g−1at approximately 2.8 V (vs.Ca2+/Ca) in the ninth cycle and showed a modest cycling performance. The capacity is the highest among the Ca cathode materials without crystal water reported to date. We revealed that the activation process was caused by a replacement reaction between the silver and calcium ions. This material demonstrates that crystal water is not an essential component of CIB electrode materials for a high capacity, stimulating the ongoing research for developing higher-performance materials. © The Royal Society of Chemistry 2021.FALS

Reversible Calcium-Ion Insertion in NASICON-Type NaV2(PO4)3

The recent discovery of reversible plating and alloying of calcium has invoked considerable interest in calcium-based rechargeable batteries toward overcoming the limitations of conventional Li-ion batteries. However, only a few cathode materials have been tested thus far, and these exhibit low energy-storage capability and poor cyclability. Herein, the highly reversible Ca-intercalation capability of NASICON-type NaV2(PO4)3 makes it a potential cathode material for nonaqueous Ca-ion batteries, with high capacity and voltage and good cyclability (90 mA h g-1 and ∼3.4 V at 11.7 mA g-1 and 75 °C; 70 mA h g-1 and ∼3.2 V at 5.85 mA g-1 and 25 °C). Although this work shows only the capability of the cathode, not a full-cell performance, it does demonstrate experimentally that a poly-oxyanionic material can provide an outstanding host structure for Ca diffusion at room temperature with high energy-storage capability. © 2020 American Chemical Society.1