The superior lithium storage performance of commercially available Cu 2 S under ultra-low temperature (−60 °C) is uncovered. The detailed reaction mechanism and mechanistic understanding of the excellent low-temperature performances are proposed.
Nonaqueous potassium-ion batteries (KIBs) are attracting increasing attention as a potential low-cost energy-storage system due to the abundance of potassium resources. Here, cobalt hexacyanocobaltate (Co3 [Co(CN)6 ]2 ), a typical Prussian blue analog (PBA), is reported as an anode material for nonaqueous KIBs. The as-prepared Co3 [Co(CN)6 ]2 exhibits a highly reversible capacity of 324.5 mAh g-1 at a current density of 0.1 A g-1 , a superior rate capability (221 mAh g-1 at 1 A g-1 ), and a favorable long-term cycling stability (200 cycles with 82% capacity retention). Based on a series of characterizations, it is found that potassiation/depotassiation in Co3 [Co(CN)6 ]2 proceeds via solid-state diffusion-limited K-ion insertion/extraction process, in which both carbon- and nitrogen-coordinated cobalt are electrochemically active toward K-ion storage. Finally, the reaction pathway between potassium and Co3 [Co(CN)6 ]2 is proposed. The present study provides new insights on further exploration of PBAs as high-performance electrode materials for KIBs.
Mercury is a major threat to the environment and to human health. It is highly desirable to develop a user-friendly kit for on-site mercury detection. Such a method must be able to detect mercury below the threshold levels (10 nM) for drinking water defined by the U.S. Environmental Protection Agency. Herein, we for the first time reported catalytically active gold amalgam-based reaction between 4-nitrophenol and NaBH4 with colorimetric sensing function. We take advantage of the correlation between the catalytic properties and the surface area of gold amalgam, which is proportional to the amount of the gold nanoparticle (AuNP)-bound Hg(2+). As the concentration of Hg(2+) increases until the saturation of Hg onto the AuNPs, the catalytic performance of the gold amalgam is much stronger due to the formation of gold amalgam and the increase of the nanoparticle surface area, leading to the decrease of the reduction time of 4-nitrophenol for the color change. This sensing system exhibits excellent selectivity and ultrahigh sensitivity up to the 1.45 nM detection limit. The practical use of this system for Hg(2+) determination in tap water samples is also demonstrated successfully.
Weak Lewis acidity of potassium-ions promotes enhanced anion incorporation into the solvation shell, facilitating the formation of a more stable and dissolution-resistant solid electrolyte interphase for K metal compared with that for Li and Na metals.
Abstract Free from strategically important elements such as lithium, nickel, cobalt, and copper, potassium‐ion batteries (PIBs) are heralded as promising low‐cost and sustainable electrochemical energy storage systems that complement the existing lithium‐ion batteries (LIBs). However, the reported electrochemical performance of PIBs is still suboptimal, especially under practically relevant battery manufacturing conditions. The primary challenge stems from the lack of electrolytes capable of concurrently supporting both the low‐voltage anode and high‐voltage cathode with satisfactory Coulombic efficiency (CE) and cycling stability. Herein, we report a promising electrolyte that facilitates the commercially mature graphite anode (>3 mAh cm −2 ) to achieve an initial CE of 91.14 % (with an average cycling CE around 99.94 %), fast redox kinetics, and negligible capacity fading for hundreds of cycles. Meanwhile, the electrolyte also demonstrates good compatibility with the 4.4 V ( vs . K + /K) high‐voltage K 2 Mn[Fe(CN) 6 ] (KMF) cathode. Consequently, the KMF||graphite full‐cell without precycling treatment of both electrodes can provide an average discharge voltage of 3.61 V with a specific energy of 316.5 Wh kg −1 −(KMF+graphite), comparable to the LiFePO 4 ||graphite LIBs, and maintain 71.01 % capacity retention after 2000 cycles.
Abstract The limited oxidation stability of ether solvents has posed significant challenges for their applications in high‐voltage lithium metal batteries (LMBs). To tackle this issue, the prevailing strategy either adopts a high concentration of fluorinated salts or relies on highly fluorinated solvents, which will significantly increase the manufacturing cost and create severe environmental hazards. Herein, an alternative and sustainable salt engineering approach is proposed to enable the utilization of dilute electrolytes consisting of fluorine (F)‐free ethers in high‐voltage LMBs. The proposed 0.8 M electrolyte supports stable lithium plating‐stripping with a high Coulombic efficiency of 99.47 % and effectively mitigates the metal dissolution, phase transition, and gas release issues of the LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode upon charging to high voltages. Consequently, the 4.5 V high‐loading Li||NCM 811 cell shows a capacity retention of 75.2 % after 300 cycles. Multimodal experimental characterizations coupled with theoretical investigations demonstrate that the boron‐containing salt plays a pivotal role in forming the passivation layers on both anode and cathode. The present simple and cost‐effective electrolyte design strategy offers a promising and alternative avenue for using commercially mature, environmentally benign, and low‐cost F‐free ethers in high‐voltage LMBs.
Abstract Biomass‐derived hard carbon (HC) has emerged as a promising candidate for anode materials of potassium‐ion batteries because of low cost and abundant raw materials. Whereas, the large specific surface area and high porosity of this type of HC often lead to inferior initial Coulombic efficiency (ICE) and unsatisfactory cycling stability. Herein, we report a coconut shell‐derived HC (CS‐HC) featuring an expanded interlayer spacing and small specific surface area. The CS‐HC delivers a reversible specific capacity of 280 mAh g −1 and an impressive ICE of 87.32 % at 50 mA g −1 . In addition, it exhibits stable cycling performance (92.8 % capacity retention after 100 cycles at 50 mA g −1 ) and fast rate capability (∼280 mAh g −1 at 300 mA g −1 ). The ex situ Raman spectra characterization combined with cyclic voltammetry tests elucidate that the storage of potassium ions in the present HC is mainly achieved by (pseudo)capacitive behavior at the disordered defect sites along with minor contribution from the interlayer intercalation process. Finally, a full‐cell constructed with unprecycled CS‐HC anode and high‐voltage K 2 Mn[Fe(CN)] 6 cathode demonstrates exceptional electrochemical stability and retains 90.6 % capacity after 100 cycles. This work reports a high‐performance HC anode material derived from low‐cost and sustainable biomass for practical potassium‐ion batteries.
Abstract Improving the fracture resistance of nacre‐inspired composites is crucial in addressing the strength‐toughness trade‐off. However, most previously proposed strategies for enhancing fracture resistance in these composites have been limited to interfacial modification by polymer, which restricts mechanical enhancement. Here, a composite material consisting of graphene oxide (GO) lamellae and nanocrystalline reinforced amorphous alumina nanowires (NAANs) has been developed. The structure of the composite is inspired by nacre and is composed of stacked GO nanosheets with NAANs in between, forming a sandwich‐like structure. This design enhances the fracture resistance of the composite through the pull‐out of GO nanosheets at the nanoscale and GO/NAANs sandwich‐like coupling at the micro‐scale, while also providing stiff ceramic support. This composite simultaneously possesses high strength (887.8 MPa), toughness (31.6 MJ m −3 ), superior cyclic stability (1600 cycles), and long‐term (2 years) immersion stability, which outperform previously reported GO‐based lamellar composites. The hierarchical fracture design provides a new path to design next‐generation strong, tough, and stable materials for advanced engineering applications.
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