More Ca 2+ , Less Na + : Increasethe Desalination Capacity and Performance Stability of Na x Ca y CoO 2
07 Aug 2019-ACS Sustainable Chemistry & Engineering (ACS Publications)-Vol. 7, Iss: 17, pp 14561-14568
TL;DR: In this paper, an asymmetric Faradaic deionization (FDI) device assembled by Ca2+decorated NaxCoO2 (x ≤ 0.71, y ≥ 0.05) as the negative electrode and activated carbon as the positive electrode was developed.
Abstract: Faradaic deionization (FDI) provides an effective solution to respond to the global water crisis. However, the ions intercalation/deintercalation process with multiple redox reactions leads to structural collapse and unstable cyclability. Here, we develop an asymmetrical FDI device assembled by Ca2+-decorated NaxCoO2 (x ≤ 0.71, y ≤ 0.05) as the Faradaic negative electrode and activated carbon as the positive electrode. Na0.27Ca0.03CoO2·0.6H2O was synthesized via a facile sol–gel and chemical oxidation method, which delivered a desalination capacity of 83.5 ± 2.4 mg g–1 and a charge efficiency close to 1, and an inappreciable capacity fading was observed after 50 cycles. It is found that the presence of Ca2+ residing in the face-sharing sites helps to maintain the layered structure and promotes efficient deintercalation of Na+ by anchoring the CoO2 slabs, which results in its unexpected desalination capacity and good cyclability. Moreover, electrochemical quartz-crystal microbalance (EQCM) was successfully...
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TL;DR: In this paper, a MOF-derived carbon/Y-stabilized ZrO2 nanocomposite (C@YSZ) was used as an efficient electrocatalyst for NRR in 0.1 M Na2SO4.
Abstract: Industrially, NH3 synthesis is largely dependent on the Haber–Bosch method which consumes a lot of energy and emits huge amounts of CO2. Recently, the electrochemical N2 reduction reaction (NRR) has been recognized as a promising method to achieve clean and sustainable NH3 production, thus highly efficient and durable catalysts are urgently desired. In this paper, we report a MOF-derived carbon/Y-stabilized ZrO2 nanocomposite (C@YSZ) that works as an efficient electrocatalyst for NRR in 0.1 M Na2SO4. It achieves a large NH3 production of 24.6 μg h−1 mgcat.−1 and a high faradaic efficiency of 8.2% at −0.5 V vs. the reversible hydrogen electrode. The experimental results demonstrate that the surface oxygen vacancies are the main catalytic sites for NRR. Introducing Y3+ into the ZrO2 lattice has a significant effect to increase and stabilize the O-vacancies. Meanwhile, this catalyst displays remarkable stability and durability for NRR, showing negligible change after 7 days reaction, which is better than most reported NRR electrocatalysts. Moreover, an in situ electrochemical quartz-crystal microbalance (EQCM) was applied in the NRR field for the first time and was successfully combined with density functional theory (DFT) calculations to reveal the deactivation mechanism.
41 citations
TL;DR: In this article, an asymmetrical FDI device was developed where NaxCoO2 as the Faradic electrode material and AC act as the Cl-storage electrode material for the first time to explore the effect of Na+/vacancy ordering on desalination performance.
10 citations
TL;DR: In this paper, a variety of battery materials have been developed due to the urgent demand for energy storage, which increases the choices of CDI electrode materials largely, revealing a bright future of integrating battery materials with CDI technology.
Abstract: The world is suffering from chronic water shortage due to the increasing population, water pollution and industrialization. Desalinating saline water offers a rational choice to produce fresh water thus resolving the crisis. Among various kinds of desalination technologies, capacitive deionization (CDI) is of significant potential owing to the facile process, low energy consumption, mild working conditions, easy regeneration, low cost and the absence of secondary pollution. The electrode material is an essential component for desalination performance. The most used electrode material is carbon-based material, which suffers from low desalination capacity (under 15 mg·g−1). However, the desalination of saline water with the CDI method is usually the charging process of a battery or supercapacitor. The electrochemical capacity of battery electrode material is relatively high because of the larger scale of charge transfer due to the redox reaction, thus leading to a larger desalination capacity in the CDI system. A variety of battery materials have been developed due to the urgent demand for energy storage, which increases the choices of CDI electrode materials largely. Sodium-ion battery materials, lithium-ion battery materials, chloride-ion battery materials, conducting polymers, radical polymers, and flow battery electrode materials have appeared in the literature of CDI research, many of which enhanced the deionization performances of CDI, revealing a bright future of integrating battery materials with CDI technology.
10 citations
TL;DR: Simultaneously regulating the physical properties and chemical environment of interlayer is a critical need for enhancing the capacity and stability of layered electrode materials in energy and env... as mentioned in this paper,...
Abstract: Simultaneously regulating the physical properties and chemical environment of interlayer is a critical need for enhancing the capacity and stability of layered electrode materials in energy and env...
9 citations
TL;DR: In this article, a series of Na0·74CoO2/C/N-based composites were fabricated by sintering the mixtures of ZIF-4(Co) (Co [H2C3N2]2) and Na2CO3.
8 citations
References
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TL;DR: More than twenty 2D carbides, nitrides and carbonitrides of transition metals (MXenes) have been synthesized and studied, and dozens more predicted to exist.
Abstract: The family of 2D transition metal carbides, carbonitrides and nitrides (collectively referred to as MXenes) has expanded rapidly since the discovery of Ti3C2 in 2011. The materials reported so far always have surface terminations, such as hydroxyl, oxygen or fluorine, which impart hydrophilicity to their surfaces. About 20 different MXenes have been synthesized, and the structures and properties of dozens more have been theoretically predicted. The availability of solid solutions, the control of surface terminations and a recent discovery of multi-transition-metal layered MXenes offer the potential for synthesis of many new structures. The versatile chemistry of MXenes allows the tuning of properties for applications including energy storage, electromagnetic interference shielding, reinforcement for composites, water purification, gas- and biosensors, lubrication, and photo-, electro- and chemical catalysis. Attractive electronic, optical, plasmonic and thermoelectric properties have also been shown. In this Review, we present the synthesis, structure and properties of MXenes, as well as their energy storage and related applications, and an outlook for future research. More than twenty 2D carbides, nitrides and carbonitrides of transition metals (MXenes) have been synthesized and studied, and dozens more predicted to exist. Highly electrically conductive MXenes show promise in electrical energy storage, electromagnetic interference shielding, electrocatalysis, plasmonics and other applications.
4,745 citations
TL;DR: In this paper, the difference between Na-ion and Li-ion based intercalation chemistries in terms of three key battery properties, voltage, phase stability and diffusion barriers was compared.
Abstract: To evaluate the potential of Na-ion batteries, we contrast in this work the difference between Na-ion and Li-ion based intercalation chemistries in terms of three key battery properties—voltage, phase stability and diffusion barriers. The compounds investigated comprise the layered AMO2 and AMS2 structures, the olivine and maricite AMPO4 structures, and the NASICON A3V2(PO4)3 structures. The calculated Na voltages for the compounds investigated are 0.18–0.57 V lower than that of the corresponding Li voltages, in agreement with previous experimental data. We believe the observed lower voltages for Na compounds are predominantly a cathodic effect related to the much smaller energy gain from inserting Na into the host structure compared to inserting Li. We also found a relatively strong dependence of battery properties on structural features. In general, the difference between the Na and Li voltage of the same structure, ΔVNa–Li, is less negative for the maricite structures preferred by Na, and more negative for the olivine structures preferred by Li. The layered compounds have the most negative ΔVNa–Li. In terms of phase stability, we found that open structures, such as the layered and NASICON structures, that are better able to accommodate the larger Na+ ion generally have both Na and Li versions of the same compound. For the close-packed AMPO4 structures, our results show that Na generally prefers the maricite structure, while Li prefers the olivine structure, in agreement with previous experimental work. We also found surprising evidence that the barriers for Na+ migration can potentially be lower than that for Li+ migration in the layered structures. Overall, our findings indicate that Na-ion systems can be competitive with Li-ion systems.
1,138 citations
01 Jan 2012
Abstract: To evaluate the potential of Na-ion batteries, we contrast in this work the difference between Na-ion and Li-ion based intercalation chemistries in terms of three key battery properties—voltage, phase stability and diffusion barriers. The compounds investigated comprise the layered AMO2 and AMS2 structures, the olivine and maricite AMPO4 structures, and the NASICON A3V2(PO4)3 structures. The calculated Na voltages for the compounds investigated are 0.18–0.57 V lower than that of the corresponding Li voltages, in agreement with previous experimental data. We believe the observed lower voltages for Na compounds are predominantly a cathodic effect related to the much smaller energy gain from inserting Na into the host structure compared to inserting Li. We also found a relatively strong dependence of battery properties on structural features. In general, the difference between the Na and Li voltage of the same structure, DVNa–Li, is less negative for the maricite structures preferred by Na, and more negative for the olivine structures preferred by Li. The layered compounds have the most negative DVNa–Li. In terms of phase stability, we found that open structures, such as the layered and NASICON structures, that are better able to accommodate the larger Na+ ion generally have both Na and Li versions of the same compound. For the close-packed AMPO4 structures, our results show that Na generally prefers the maricite structure, while Li prefers the olivine structure, in agreement with previous experimental work. We also found surprising evidence that the barriers for Na+ migration can potentially be lower than that for Li+ migration in the layered structures. Overall, our findings indicate that Na-ion systems can be competitive with Li-ion systems.
1,109 citations
TL;DR: The results suggest that the H2 O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2 O5 framework, effectively promoting its diffusion.
Abstract: Low-cost, environment-friendly aqueous Zn batteries have great potential for large-scale energy storage, but the intercalation of zinc ions in the cathode materials is challenging and complex. Herein, the critical role of structural H2O on Zn2+ intercalation into bilayer V2O5·nH2O is demonstrated. The results suggest that the H2O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2O5 framework, effectively promoting its diffusion. Benefited from the “lubricating” effect, the aqueous Zn battery shows a specific energy of ≈144 Wh kg−1 at 0.3 A g−1. Meanwhile, it can maintain an energy density of 90 Wh kg−1 at a high power density of 6.4 kW kg−1 (based on the cathode and 200% Zn anode), making it a promising candidate for high-performance, low-cost, safe, and environment-friendly energy-storage devices.
987 citations