ABSTRACT
The unstable electrode-electrolyte interface and the narrow electrochemical window of normal electrolytes hinder the potential application of high-voltage sodium metal batteries. These problems are actually related to the solvation structure of the electrolyte, which is determined by the competition between cations coordinated with anions or solvent molecules. Herein, we design an electrolyte incorporating ethyl (2,2,2-trifluoroethyl) carbonate and fluoroethylene carbonate, which facilitates a pronounced level of cation-anion coordination within the solvation sheath by enthalpy changes to reduce the overall coordination of cation-solvents and increase sensitivity to salt concentration. Such an electrolyte regulated by competitive coordination leads to highly reversible sodium plating/stripping with extended cycle life and a high Coulombic efficiency of 98.0%, which is the highest reported so far in Na||Cu cells with ester-based electrolytes. Moreover, 4.5 V high-voltage Na||Na3V2(PO4)2F3 cells exhibit a high rate capability up to 20 C and an impressive cycling stability with an 87.1% capacity retention after 250 cycles with limited Na. The proposed strategy of solvation structure modification by regulating the competitive coordination of the cation provides a new direction to achieve stable sodium metal batteries with high energy density and can be further extended to other battery systems by controlling enthalpy changes of the solvation structure.
ABSTRACT
Supported polyethyleneimine (PEI) adsorbent is one of the most promising commercial direct air capture (DAC) adsorbents with a long research history since 2002. Although great efforts have been input, there are still limited improvements for this material in its CO2 capacity and adsorption kinetics under ultradilute conditions. Supported PEI also suffers significantly reduced adsorption capacities when working at sub-ambient temperatures. This study reports that mixing diethanolamine (DEA) into supported PEI can increase 46% and 176% of pseudoequilibrium CO2 capacities at DAC conditions compared to the supported PEI and DEA, respectively. The mixed DEA/PEI functionalized adsorbents maintain the adsorption capacity at sub-ambient temperatures of -5 to 25 °C. In comparison, a 55% reduction of CO2 capacity is observed for supported PEI when the operating temperature decreases from 25 to -5 °C. In addition, the supported mixed DEA/PEI with a ratio of 1:1 also shows fast desorption kinetics at temperatures as low as 70 °C, resulting in maintaining high thermal and chemical stability over 50 DAC cycles with a high average CO2 working capacity of 1.29 mmol g-1 . These findings suggest that the concept of "mixed amine", widely studied in the solvent system, is also practical to supported amine for DAC applications.
ABSTRACT
Lithium metal is an ideal electrode material for future rechargeable batteries. However, dendrite formation and unstable solid electrolyte interphase film lead to safety concerns and poor Coulombic efficiency (CE). LiNO3 significantly improves the performance of the lithium metal anode in ester electrolytes but its use is restricted by low solubility. To increase the content of LiNO3 in the cell, a poly-(vinyl carbonate) organogel interlayer containing dissociated LiNO3 (LNO-PVC) is placed between the cathode and anode. The dissociated LiNO3 effectively increases the LiNO3 -release rate and compensates for the LiNO3 consumed in ester electrolytes during cycling. Via this interlayer, the performance of the lithium metal anode is significantly improved. The average CE of a Li-Cu cell reaches 98.6% at 0.5 mA cm-2 -1 h and 98.5% at 1 mA cm-2 -1 h for 300 cycles. Also, a Li||NCM811 pouch cell with LNO-PVC interlayer can also reach a 400 Wh kg-1 energy density with a cycling life of 65 cycles. This strategy sheds light on the effect of the state of this salt on its release/dissolution kinetics, which is determined by the interactions between the salt and host material.
ABSTRACT
Municipal solid waste incinerator fly ash (MSWI FA) is a type of waste that is harmful to the environment, and the melting treatment methods can treat MSWI FA, removing its potential negative impacts. However, special equipment is required for the FA melting process, which necessitates high costs. Metallurgical shaft furnaces (MSF) can melt MSWI FA efficiently. Therefore, the feasibility of using an MSF for FA treatment was studied herein. First, the fundamental physicochemical properties of the FA were analyzed. Then, the appearance and internal morphology of the FA were examined using a scanning electron microscope. Finally, melting experiments were designed according to the conditions of the MSF. The results show that slag changes into a glassy state under rapid cooling, which is beneficial to the solidification of harmful elements. These harmful elements, including Pb, Zn, and Cu, are thus reduced and volatilized into the flue gas under the MSF's reducing atmosphere. The harmful elements that enter the slag are solidified, causing its leaching toxicity to achieve the national standard requirements. Further, under the simulated MSF smelting conditions, the FA dioxin destroy removal efficiency realized more than 99.99% efficiency. Therefore, the harmless treatment of MAWI FA can be realized through MSF process.
Subject(s)
Metals, Heavy , Refuse Disposal , Carbon , Coal Ash , Incineration , Metals, Heavy/analysis , Particulate Matter , Solid WasteABSTRACT
Due to the high proportion of the steel output produced by oxygen converter, significant quantities of converter sludge (CS) is generated annually as waste material. This study aims to review the latest CS utilization technologies and illuminate the migration behaviors of harmful substances as well as valuable elements. The intrinsic characteristics, including chemical constitution, size distribution, mineralogical composition, microstructure, and viscosity of the CS are studied. Migration behaviors of harmful substances are analyzed based on thermodynamic calculation. The results indicated that less eutectic mineral was found in CS, the iron oxides and other impurities like CaO, MgO and ZnFe2O4 mixed in the way of physical accumulation. The treatments through oxidation methods, such as iron ore sintering and oxidized pellets, are the most common and effective methods to recovery Fe in actual production. Due to the diverse physicochemical properties of CS from different enterprises, it is really difficult to choose one universal recovery method. In view of resources recovery and clean production, the authors believe that the best utilization technology at present is to prepare metallized pellets. It is regarded that technologies of preparing high value-added products, such as Li(FeM)PO4 and iron powder are the most prospective methods in the future.
