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1.
Artigo em Inglês | MEDLINE | ID: mdl-33354840

RESUMO

Dual-ion batteries (DIBs) inherently suffer from limited energy density due to insufficient anion storage capacity of typical graphite cathodes. Herein, we propose a new design strategy to effectively tackle this issue via employing locally ordered graphitized carbon (LOGC) cathodes. Quantum mechanical modeling suggests that strong anion-anion repulsion and severe expansion at the deep-charging stage raise the anion intercalation voltage, therefore only part of the theoretical anion storage sites in graphite is accessible. The LOGC interconnected with disordered carbon is predicted to weaken the interlaminar van der Waals interaction, while disordered carbons not only interconnect the dispersed nano-graphite but also partially buffer severe anion-anion repulsion and offer extra capacitive anion storage sites. As a proof-of-concept, ketjen black (KB) with the typical feature of LOGC is selected as a model cathode for a potassium-based DIB (KDIB). The KDIB delivers an unprecedentedly high specific capacity of 232 mAh g -1 at 50 mA g -1 , a good rate capability of 110 mAh g -1 at 2000 mA g -1 and excellent cycling stability of 1000 cycles without obvious capacity fading.

2.
ACS Nano ; 14(9): 12016-12026, 2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32833424

RESUMO

Redox-active organic cathode materials have drawn growing attention because of the broad availability of raw materials, eco-friendliness, scalable production, and diverse structural flexibility. However, organic materials commonly suffer from fragile stability in organic solvents, poor electrochemical stability in charge/discharge processes, and insufficient electrical conductivity. To address these issues, using Cu(II) salt and benzenehexathiolate (BHT) as the precursors, we synthesized a robust and redox-active 2D metal-organic framework (MOF), [Cu3(C6S6)]n, namely, Cu-BHT. The Cu-BHT MOFs have a highly conjugated structure, affording a high electronic conductivity of 231 S cm-1, which could further be increased upon lithiation in lithium-ion battery (LIB) applications. A reversible four-electron reaction reveals the Li storage mechanism of the Cu-BHT for a theoretical capacity of 236 mAh g-1. The as-prepared Cu-BHT cathode delivers an excellent reversible capacity of 175 mAh g-1 with ultralow capacity deterioration (0.048% per cycle) upon 500 cycles at a high current density of 300 mA g-1. Therefore, we believe this work would provide a practical strategy for the development of high-power energy storage materials.

4.
ACS Appl Mater Interfaces ; 12(23): 25875-25883, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32421309

RESUMO

Graphene is commonly used to improve the electrochemical performance of electrode materials in rechargeable batteries by forming graphene-based heterostructures. Two-dimensional graphitic carbon nitride (C3N4) is an analogue of graphene, and it is often used to form 1D/2D and 2D/2D C3N4/graphene heterostructures. However, a theoretical understanding of the heterointerface in these heterostructures and how this affects their electrochemical performance is lacking. In this work we study the heterointerface of 1D/2D and 2D/2D C3N4/graphene heterostructures and how the different dimensions influence the lithium ion battery performance of the heterostructure. Our density functional theory (DFT) study showed that the common problem of C-N bond breakage experienced in 2D/2D C3N4/graphene heterostructure does not occur in the 1D/2D heterostructure. Furthermore, the 1D/2D heterostructure showed superior conductivity in comparison to that of the 2D/2D heterostructure of C3N4/graphene. The 1D/2D C3N4/graphene heterostructure also recorded a high theoretical capacity and rapid charge transfer. These results suggest that the properties of a heterostructure are influenced by the dimension of materials at the interface. These discoveries on the relationship between material dimension in heterostructure electrodes and their electrochemical performance will motivate the design of advanced electrode materials for rechargeable batteries.

5.
ACS Appl Mater Interfaces ; 12(22): 25494-25502, 2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32401012

RESUMO

Creatively constructing Z-scheme composites is a promising and common strategy for designing effective photocatalyst systems. Herein, we synthesized Z-scheme Fe2O3@Ag-ZnO@C heterostructures from the Fe-MOFs and applied it to photodegradation of tetracycline and methylene blue pollutants in wastewater. The optimized sample exhibits a remarkable performance as well as stability under visible light irradiation. The calculating and experimental results demonstrate that the Fe2O3@ZnO nanointerface and carbon sheath together boost the transfer efficiency of photogenerated carriers and absorption ability, thereby improving the photocatalytic activity. Furthermore, detailed mechanism investigation reveals the pivotal role of reactive oxygen species (•OH and •O2-) generated, resulting in remarkable performance. In addition, cell biology experiments reveal that the wastewater after photocatalytic treatment has good biological compatibility, which is important for applications. This work provides valuable information for constructing high-performance Z-scheme photocatalysts from MOFs for environmental treatment.

7.
ACS Appl Mater Interfaces ; 12(18): 20490-20499, 2020 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-32290647

RESUMO

The adsorbents for water treatment and purification are commonly not recyclable because of the lack of a reagent-less "switch" to readily release the adsorbed compounds. Herein, the interface of Bi2O2CO3 (BOC) nanosheets is designed, synthesized, and modified with citric acid, namely, modified Bi2O2CO3 (m-BOC). The m-BOC is able to selectively adsorb methylene blue (MB) in the dark and the adsorbed MB could be released in the light from m-BOC without the addition of any chemicals. The adsorption mechanism is attributed to the electrostatic attraction between positively charged MB and the negatively charged surface of m-BOC. In contrast, the desorption of MB has resulted from the photo-induced charge redistribution on the surface of m-BOC, which unlocks the coordination bond between m-BOC and the carboxylic group. As a result, BOC is recycled. Such a mechanism was verified by both experimental investigation and DFT calculation. This work provides a promising interfacial engineering strategy for the remediation of dye-polluted water and smart separation in chemical engineering.

8.
ACS Nano ; 14(4): 5027-5035, 2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32196308

RESUMO

Cobalt oxide (Co3O4) delivers a poor capacity when applied in large-sized alkali metal-ion systems such as potassium-ion batteries (KIBs). Our density functional theory calculation suggests that this is due to poor conductivity, high diffusion barrier, and weak potassium interaction. N-doped carbon can effectively attract potassium ions, improve conductivity, and reduce diffusion barriers. Through interface engineering, the properties of Co3O4 can be tuned via composite design. Herein, a Co3O4@N-doped carbon composite was designed as an advanced anode for KIBs. Due to the interfacial design of the composite, K+ were effectively transported through the Co3O4@N-C composite via multiple ionic pathways. The structural design of the composite facilitated increased Co3O4 spacing, a nitrogen-doped carbon layer reduced K-ion diffusion barrier, and improved conductivity and protected the electrode from damage. Based on the entire composite, a superior capacity of 448.7 mAh/g was delivered at 50 mA/g after 40 cycles, and moreover, 213 mAh/g was retained after 740 cycles when cycled at 500 mA/g. This performance exceeds that of most metal-oxide-based KIB anodes reported in literature.

9.
ACS Appl Mater Interfaces ; 12(15): 17592-17601, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32091194

RESUMO

Because of the severe shuttle effect of polysulfides, achieving durable Li-S batteries is still a great challenge, especially under practical operation conditions including the high sulfur content, high loading, and high operation temperature. Herein, for the first time, low-cost, eco-friendly, and hydrophilic cellulose nanocrystals (CNCs) are proposed as a multifunctional polysulfide stopper for Li-S batteries with high performance. CNCs display an intrinsically high aspect ratio and a large surface area and contain a large amount of hydroxyl groups offering a facile platform for chemical interactions. Density functional theory calculations suggest that the electron-rich functional groups on CNCs deliver robust binding energies with polysulfides. In this work, CNCs not only firmly confine sulfur and polysulfides in the cathode as a robust binder, but also further hinder polysulfide shuttling to the Li anode as a polysulfide stopper on a separator. Consequently, the as-prepared Li-S batteries demonstrate outstanding cycling performance even under the conditions of high sulfur content of 90 wt % (63 wt % in the cathode), high loading of 8.5 mg cm-2, and high temperature of 60 °C. These results sufficiently demonstrate that CNCs have significant application potential in Li-S battery technologies.

10.
ChemSusChem ; 13(9): 2457-2463, 2020 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31782976

RESUMO

Searching new organic cathode materials to address the issues of poor cycle stability and low capacity in lithium ion batteries (LIBs) is very important and highly desirable. In this research, a 2D boroxine-linked chemically-active pyrene-4,5,9,10-tetraone (PTO) covalent organic framework (2D PPTODB COFs) was synthesized as an organic cathode material with remarkable electrochemical properties, including high electrochemical activity (four redox electrons), safe oxidation potential window (between 2.3 and 3.08 V vs. Li/Li+ ), superb structural/chemical stability, and strong adhesiveness. A binder-free cathode was obtained by mixing 70 wt % PPTODB and 30 wt % carbon nanotubes (CNTs) as a conductive additive. Promoted by the fast kinetics of electrons/ions, high electrochemical activity, and effective π-π interaction between PPTODB and CNTs, LIBs with the as-prepared cathode exhibited excellent electrochemical performance: a high specific capacity of 198 mAh g-1 , a superb rate ability (the capacity at 1000 mA g-1 can reach 76 % of the corresponding value at 100 mA g-1 ), and a stable coulombic efficiency (≈99.6 % at the 150th cycle). This work suggests that the concept of binder-free 2D electroactive materials could be a promising strategy to approach energy storage with high energy density.

11.
Nat Commun ; 10(1): 3917, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31477733

RESUMO

Long-term stability and high-rate capability have been the major challenges of sodium-ion batteries. Layered electroactive materials with mechanically robust, chemically stable, electrically and ironically conductive networks can effectively address these issues. Herein we have successfully directed carbon nanofibers to vertically penetrate through graphene sheets, constructing robust carbon nanofiber interpenetrated graphene architecture. Molybdenum disulfide nanoflakes are then grown in situ alongside the entire framework, yielding molybdenum disulfide@carbon nanofiber interpenetrated graphene structure. In such a design, carbon nanofibers prevent the restacking of graphene sheets and provide ample space between graphene sheets, enabling a strong structure that maintains exceptional mechanical integrity and excellent electrical conductivity. The as-prepared sodium ion battery delivers outstanding electrochemical performance and ultrahigh stability, achieving a remarkable specific capacity of 598 mAh g-1, long-term cycling stability up to 1000 cycles, and an excellent rate performance even at a high current density up to 10 A g-1.

12.
ACS Sens ; 4(7): 1881-1888, 2019 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-31244006

RESUMO

Ammonia is a necessary monitoring parameter that should be controlled within an optimum range in the whole process of wastewater treatment and recycling, but few reliable real-time monitoring technologies are available currently under such harsh water conditions. This study proposes a continuous conductometric flow-through analyzer for ammonia monitoring (CFAA) in the wastewater treatment process. It is developed based on the gas diffusion mechanisms, and the proposed analytical principle has been validated in which the real-time conductivity increment rate is linearly proportional to the real-time ammonia concentration in the sample. This method could be generally applicable in monitoring a wide ammonia concentration range (10.2 µg L-1 to 500 mg L-1), and it is capable of achieving long-term ammonia monitoring by periodic renewal of the receiving solution. The potential impact factors and corresponding calibration principles are also developed to avoid tedious ongoing calibration. The field application results demonstrate that CFAA can effectively and directly achieve real-time and average ammoniacal nitrogen monitoring at different treatment stages regardless of the complexity of wastewater, not requiring any sample pretreatment. Compared with other ammonia online monitoring technologies, the proposed CFAA shows remarkable advantages in high reliability, durability, and accuracy, especially under severe monitoring condition. It can be a useful monitoring tool for continuous ammonia control in the wastewater treatment process.


Assuntos
Amônia/análise , Difusão , Técnicas Eletroquímicas/métodos , Membranas Artificiais , Águas Residuárias/análise , Ácidos Bóricos , Técnicas Eletroquímicas/instrumentação , Temperatura
13.
Nat Commun ; 10(1): 1965, 2019 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-31036805

RESUMO

Large-scale applications of rechargeable batteries consume nonrenewable resources and produce massive amounts of end-of-life wastes, which raise sustainability concerns in terms of manufacturing, environmental, and ecological costs. Therefore, the recyclability and sustainability of a battery should be considered at the design stage by using naturally abundant resources and recyclable battery technology. Herein, we design a fully recyclable rechargeable sodium ion battery with bipolar electrode structure using Na3V2(PO4)3 as an electrode material and aluminum foil as the shared current collector. Such a design allows exceptional sodium ion battery performance in terms of high-power correspondence and long-term stability and enables the recycling of ∼100% Na3V2(PO4)3 and ∼99.1% elemental aluminum without the release of toxic wastes, resulting in a solid-component recycling efficiency of >98.0%. The successful incorporation of sustainability into battery design suggests that closed-loop recycling and the reutilization of battery materials can be achieved in next-generation energy storage technologies.

14.
Angew Chem Int Ed Engl ; 58(26): 8824-8828, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31050110

RESUMO

The poor cycling stability resulting from the large volume expansion caused by lithiation is a critical issue for Si-based anodes. Herein, we report for the first time of a new yolk-shell structured high tap density composite made of a carbon-coated rigid SiO2 outer shell to confine multiple Si NPs (yolks) and carbon nanotubes (CNTs) with embedded Fe2 O3 nanoparticles (NPs). The high tap density achieved and superior conductivity can be attributed to the efficiently utilised inner void containing multiple Si yolks, Fe2 O3 NPs, and CNTs Li+ storage materials, and the bridged spaces between the inner Si yolks and outer shell through a conductive CNTs "highway". Half cells can achieve a high area capacity of 3.6 mAh cm-2 and 95 % reversible capacity retention after 450 cycles. The full cell constructed using a Li-rich Li2 V2 O5 cathode can achieve a high reversible capacity of 260 mAh g-1 after 300 cycles.

15.
Chem Asian J ; 14(13): 2210-2214, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31016880

RESUMO

A novel conjugated copolymer has been synthesized and employed as an organic cathode material in rechargeable lithium-ion batteries (LIBs). Due to the synergistic effects from conducting aniline and pyrene units, the resultant batteries based on the as-obtained copolymer can deliver a promising reversible specific capacity of 113 mAh g-1 with a high voltage output of 3.2 V and a remarkable 75.2 % capacity retention after 180 cycles. Moreover, an excellent rate performance is also achieved with a fast recovery of the capacity at different current densities.

16.
Adv Mater ; 31(18): e1900826, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30907036

RESUMO

Aluminum (Al) is one of the most attractive anode materials for lithium-ion batteries (LIBs) due to its high theoretical specific capacity, excellent conductivity, abundance, and especially low cost. However, the large volume expansion, originating from the uneven alloying/dealloying reactions in the charge/discharge process, causes structural stress and electrode pulverization, which has long hindered its practical application, especially when assembled with a high-areal-density cathode. Here, an inactive (Cu) and active (Al) co-deposition strategy is reported to homogeneously distribute the alloying sites and disperse the stress of volume expansion, which is beneficial to obtain the structural stability of the Al anode. Owing to the homogeneous reaction and uniform distribution of stress during the charge/discharge process, the assembled full battery (LiFePO4 cathode with a high areal density of ≈7.4 mg cm-2 ) with the Cu-Al@Al anode, achieves a high capacity retention of ≈88% over 200 cycles, suggesting the feasibility of the interfacial design to optimize the structural stability of alloying metal anodes for high-performance LIBs.

17.
J Hazard Mater ; 365: 448-456, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30453238

RESUMO

The degradation of nitrobenzene by synchronistic oxidation and reduction was investigated using an internal circulation microelectrolysis (ICE) reactor with an active volume of 0.018 m3. Compared with a conventional fixed bed reactor with and without aeration, the ICE reactor exhibited a markedly higher nitrobenzene degradation efficiency. The effects of various operational parameters such as reaction time, aeration rate, initial nitrobenzene concentration, initial pH, and a volume ratio of iron and carbon (Fe/C) were also investigated. The optimal operating conditions (reaction time = 60 min, aeration rate = 5 × 10-4 m3/s, initial concentration of nitrobenzene = 300 mg/L, pH = 3.0, Fe/C = 1:1) gave removal efficiencies of nitrobenzene and chemical oxygen demand of 98.2% and 58%, respectively. The biodegradability index of the treated nitrobenzene solution was 0.45, which is 22 times that of the original solution. The reaction intermediates were identified through high-performance liquid chromatography, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and ion chromatography. The primary intermediates were determined to be aniline, phenol, and carboxylic acids, indicating that nitrobenzene was synchronously oxidized and reduced in the ICE reactor. Based on the identified intermediates, a possible pathway for nitrobenzene degradation in the ICE reactor is proposed.

18.
J Am Chem Soc ; 140(50): 17515-17521, 2018 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-30486645

RESUMO

Lithium metal is among the most promising anode materials for high-energy batteries due to its high theoretical capacity and lowest electrochemical potential. However, dendrite formation is a major challenge, which can result in fire and explosion of the batteries. Herein, we report on hexadecyl trimethylammonium chloride (CTAC) as an electrolyte additive that can suppress the growth of lithium dendrites by lithiophobic repulsion mechanisms. During the lithium plating process, cationic surfactant molecules can aggregate around protuberances via electrostatic attraction, forming a nonpolar lithiophobic protective outer layer, which drives the deposition of lithium ions to adjacent regions to produce dendrite-free uniform Li deposits. Thus, an excellent cycle of 300 h at 1.0 mA cm-2 and rate performance up to 4 mA cm-2 are available safely in symmetric Li|Li cells. In particular, significantly enhanced cycle and rate performance were achieved when the electrolyte with CTAC additives was used in lithium-sulfur and Li|LiNi0.5Co0.2Mn0.3O2 full cells. The effects of carbon chains, anions of surfactant, and electrostatic repulsion on the deposition of lithium anodes are reported. This work advances research in inhibiting Li dendrite growth with a new electrolyte additive based on cationic surfactants.

19.
Chem Rev ; 118(18): 8936-8982, 2018 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-30133259

RESUMO

Tremendous efforts have been devoted to the development of electrode materials, electrolytes, and separators of energy-storage devices to address the fundamental needs of emerging technologies such as electric vehicles, artificial intelligence, and virtual reality. However, binders, as an important component of energy-storage devices, are yet to receive similar attention. Polyvinylidene fluoride (PVDF) has been the dominant binder in the battery industry for decades despite several well-recognized drawbacks, i.e., limited binding strength due to the lack of chemical bonds with electroactive materials, insufficient mechanical properties, and low electronic and lithium-ion conductivities. The limited binding function cannot meet inherent demands of emerging electrode materials with high capacities such as silicon anodes and sulfur cathodes. To address these concerns, in this review we divide the binding between active materials and binders into two major mechanisms: mechanical interlocking and interfacial binding forces. We review existing and emerging binders, binding technology used in energy-storage devices (including lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, and supercapacitors), and state-of-the-art mechanical characterization and computational methods for binder research. Finally, we propose prospective next-generation binders for energy-storage devices from the molecular level to the macro level. Functional binders will play crucial roles in future high-performance energy-storage devices.

20.
ACS Appl Mater Interfaces ; 10(34): 28686-28694, 2018 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-30070823

RESUMO

The establishment of p-n heterojunction between semiconductors is an effective means to improve the performance of semiconductor photocatalysts. For the first time, we synthesize SnO2/BiOBr heterojunction photocatalysts using a one-step hydrothermal method. Systematic material characterizations suggest that the photocatalysts consist of irregular BiOBr nanosheets with the length about 200 nm and width about 150 nm, and SnO2 nanoparticles are anchored uniformly onto the nanosheets. Most importantly, electrochemical characterizations including transient photocurrent profiles and electrochemical impedance spectra suggest that SnO2/BiOBr heterojunctions are created, which facilitates the charge separation and transfer efficiency of photogenerated charge carriers. As such, SnO2/BiOBr photocatalysts exhibit remarkable photocatalytic activities in terms of degrading a series of organic pollutants. Radical trapping experiments and electron spin resonance spectra suggest that superoxide radicals (•O2-) and hydroxyl radicals (•OH) are primary medium species running through the photocatalytic degradation process and enhanced photocatalytic performance.

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