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1.
Small ; : e2307900, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38334199

RESUMO

As a crucial component responsible for the oxygen reduction reaction (ORR), cobalt-rich perovskite-type cathode materials have been extensively investigated in protonic ceramic fuel cell (PCFC). However, their widespread application at a commercial scale is considerably hindered by the high cost and inadequate stability. In response to these weaknesses, the study presents a novel cobalt-free perovskite oxide, Ba0.95 La0.05 (Fe0.8 Zn0.2 )0.95 O3-δ (BLFZ0.95), with the triple-conducting (H+ |O2- |e- ) property as an active and robust air electrode for PCFC. The B-site deficiency state contributes significantly to the optimization of crystal and electronic structure, as well as the increase in oxygen vacancy concentration, thus in turn favoring the catalytic capacity. As a result, the as-obtained BLFZ0.95 electrode demonstrates exceptional electrochemical performance at 700 °C, representing extremely low area-specific resistance of 0.04 Ω cm2 in humid air (3 vol.% H2 O), extraordinarily high peak power density of 1114 mW cm-2 , and improved resistance against CO2 poisoning. Furthermore, the outstanding long-term durability is achieved without visible deterioration in both symmetrical and single cell modes. This study presents a simple but crucial case for rational design of cobalt-free perovskite cathode materials with appreciable performance via B-site deficiency regulation.

2.
Small ; : e2403600, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38949410

RESUMO

BiVO4-based photoanode is one of the most promising photoanodes for photoelectrocatalytic water splitting. However, the serious problem of interface charge recombination limits its further development. Here, a Mo:BiVO4/NiOx/CPF-TCzB/NiCoBi photoanode is constructed with double hole transport layer and an energy level gradient to achieve an effective photo-generated holes extraction and accumulation at the surface electrocatalyst. The conjugated polycarbazole framework CPF-TCzB is used as hole transport layer to eliminate the charge recombination center between Mo:BiVO4 and NiCoBi electrocatalyst and realize the extraction and storage of photo-generated hole; NiOx nanoparticles are further inserted between Mo:BiVO4 and CPF-TCzB to form a gradient energy level, eliminating the energy level barrier and optimizing band alignment. As a result, Mo:BiVO4/NiOx/CPF-TCzB/NiCoBi achieves a much higher photocurrent densities of 3.14 mA cm-2 than that of Mo:BiVO4 (0.42 mA cm-2) at 0.6 V versus RHE. This work provides an specific way to adjust the band structure of BiVO4-based photoanodes and realize efficient hole extraction and storage for PEC water splitting.

3.
Chem Rev ; 122(1): 957-999, 2022 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-34709781

RESUMO

Atomically thin materials (ATMs) with thicknesses in the atomic scale (typically <5 nm) offer inherent advantages of large specific surface areas, proper crystal lattice distortion, abundant surface dangling bonds, and strong in-plane chemical bonds, making them ideal 2D platforms to construct high-performance electrode materials for rechargeable metal-ion batteries, metal-sulfur batteries, and metal-air batteries. This work reviews the synthesis and electronic property tuning of state-of-the-art ATMs, including graphene and graphene derivatives (GE/GO/rGO), graphitic carbon nitride (g-C3N4), phosphorene, covalent organic frameworks (COFs), layered transition metal dichalcogenides (TMDs), transition metal carbides, carbonitrides, and nitrides (MXenes), transition metal oxides (TMOs), and metal-organic frameworks (MOFs) for constructing next-generation high-energy-density and high-power-density rechargeable batteries to meet the needs of the rapid developments in portable electronics, electric vehicles, and smart electricity grids. We also present our viewpoints on future challenges and opportunities of constructing efficient ATMs for next-generation rechargeable batteries.

4.
J Chem Phys ; 160(14)2024 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-38591686

RESUMO

Metal-Organic Polymers (MOPs) have attracted growing attention for lithium-ion battery (LIB) applications due to their merits in orderly ionic transportation and robust structure stability in electrochemical reactions. However, they suffer from poor electronic conductivity. In this work, we apply first-principles density functional theory to explore the potential of three one-dimensional (1D) electrically conductive C6H2S4TM (TM = Fe, Co, and Ni) MOPs with the π-d conjugated coordination as anode materials for Li+ ions storage. Our theoretical results reveal that these 1D MOPs possess a superior theoretical capacity of over 748 mA h g-1. In particular, the 1D C6H2S4Ni MOP shows an exceptional theoretical specific capacity of 1110 mA h g-1 based on the three-electron transferring reaction, which significantly outperforms the traditional graphite-based anode material in LIBs. Moreover, the resonant charge transfer between Ni metal and ligand within the 1D C6H2S4Ni MOP reduces the diffusion energy barrier of the Li atoms when they migrate on the surface of the MOP. The ultrahigh theoretical specific capacity of the C6H2S4Ni MOP predicts that it can be a promising anode material for LIBs.

5.
Angew Chem Int Ed Engl ; 63(5): e202315087, 2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38087471

RESUMO

The reaction rate bottleneck during interconversion between insulating S8 (S) and Li2 S fundamentally leads to incomplete conversion and restricted lifespan of Li-S battery, especially under high S loading and lean electrolyte conditions. Herein, we demonstrate a new catalytic chemistry: soluble semiquinone, 2-tertbutyl-semianthraquinone lithium (Li+ TBAQ⋅- ), as both e- /Li+ donor and acceptor for simultaneous S reduction and Li2 S oxidation. The efficient activation of S and Li2 S by Li+ TBAQ⋅- in the initial discharging/charging state maximizes the amount of soluble lithium polysulfide, thereby substantially improve the rate of solid-liquid-solid reaction by promoting long-range electron transfer. With in situ Raman spectra and theoretical calculations, we reveal that the activation of S/Li2 S is the rate-limiting step for effective S utilization under high S loading and low E/S ratio. Beyond that, the S activation ratio is firstly proposed as an accurate indicator to quantitatively evaluate the reaction rate. As a result, the Li-S batteries with Li+ TBAQ⋅- deliver superior cycling performance and over 5 times higher S utilization ratio at high S loading of 7.0 mg cm-2 and a current rate of 1 C compared to those without Li+ TBAQ⋅- . We hope this study contributes to the fundamental understanding of S redox chemical and inspires the design of efficient catalysis for advanced Li-S batteries.

6.
Acc Chem Res ; 55(15): 2088-2102, 2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35866547

RESUMO

ConspectusSilicon-based anode materials have become a research hot spot as the most promising candidates for next-generation high-capacity lithium-ion batteries. However, the irreversible degradation of the conductive network in the anode and the resultant dramatic capacity loss have become two ultimate challenges that stem from inherent characteristics of the Si-based materials, including poor conductivity and massive volume changes (up to 300%) during cycling. Apart from optimization of the active materials, one effective way to stabilize high-capacity Si-based anodes is by designing polymeric binders to reinforce the conductive networks during repeated charge and discharge processes. As an inactive component in the electrode, the binder not only holds other components (e.g., active materials, conductive agents, and current collectors) together to maintain the mechanical integrity of the electrode but also serves as a thickener to facilitate the homogeneous distribution of particles. Therefore, binders play a key role in Si-based anodes by maintaining the integrity of conductive networks in the electrode.In this Account, on the basis of the extensive binder-related work on Si-based anodes since the 2000s, efforts made on maintaining the conductive network can be categorized into two main strategies: (1) stabilization of the primary conductive network (which generally refers to conductive agents) by enhancing the binding strength and resilience of the binding between electrode components (i.e., Si particles, conducting agents, and current collectors) via various interactions (e.g., dipolar interactions and covalent bonds) and (2) construction of the secondary conductive network by employing conductive binders, which serve as a molecular-level conductive layer on active materials. In this sense, functional groups in binders can be divided into two categories: mechanical structural units and conductive structural units. On the one hand, functional groups with strong polarities (e.g., -OH, -COOH, -NH2, and -CONH-) generally serve as binding structural units because of their bonding tendencies; on the other hand, exhibiting high electronic conductivity, conjugated functional groups (e.g., -C4H4O2S-, -C16H9, -C13H8-, and -C12H8N-) are commonly found in conductive binders. Through establishing the correlation between structural units and their corresponding properties, we systematically summarize the optimization strategies and design principles of binders to achieve a robust conductive network in Si-based anodes. In addition, integration of desirable mechanical properties and high conductivity into the binder in order to achieve a multidimensionally stable conductive network is proposed. Through an insightful retrospective and prospective on binders, a key electrode component, we hope to provide a fresh perspective on performance optimization of Si-based anodes.

7.
Chem Soc Rev ; 51(18): 8045-8101, 2022 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-36047454

RESUMO

Lithium-air batteries (LABs) have attracted tremendous attention since the proposal of the LAB concept in 1996 because LABs have a super high theoretical/practical specific energy and an infinite supply of redox-active materials, and are environment-friendly. However, due to the lack of critical electrode materials and a thorough understanding of the chemistry of LABs, the development of LABs entered a germination period before 2010, when LABs research mainly focused on the development of air cathodes and carbonate-based electrolytes. In the growing period, i.e., from 2010 to the present, the investigation focused more on systematic electrode design, fabrication, and modification, as well as the comprehensive selection of electrolyte components. Nevertheless, over the past 25 years, the development of LABs has been full of retrospective steps and breakthroughs. In this review, the evolution of LABs is illustrated along with the constantly emerging design, fabrication, modification, and optimization strategies. At the end, perspectives and strategies are put forward for the development of future LABs and even other metal-air batteries.


Assuntos
Fontes de Energia Elétrica , Lítio , Eletrodos , Íons , Estudos Retrospectivos
8.
Sensors (Basel) ; 23(12)2023 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-37420527

RESUMO

Infrared images have been widely used in many research areas, such as target detection and scene monitoring. Therefore, the copyright protection of infrared images is very important. In order to accomplish the goal of image-copyright protection, a large number of image-steganography algorithms have been studied in the last two decades. Most of the existing image-steganography algorithms hide information based on the prediction error of pixels. Consequently, reducing the prediction error of pixels is very important for steganography algorithms. In this paper, we propose a novel framework SSCNNP: a Convolutional Neural-Network Predictor (CNNP) based on Smooth-Wavelet Transform (SWT) and Squeeze-Excitation (SE) attention for infrared image prediction, which combines Convolutional Neural Network (CNN) with SWT. Firstly, the Super-Resolution Convolutional Neural Network (SRCNN) and SWT are used for preprocessing half of the input infrared image. Then, CNNP is applied to predict the other half of the infrared image. To improve the prediction accuracy of CNNP, an attention mechanism is added to the proposed model. The experimental results demonstrate that the proposed algorithm reduces the prediction error of the pixels due to full utilization of the features around the pixel in both the spatial and the frequency domain. Moreover, the proposed model does not require either expensive equipment or a large amount of storage space during the training process. Experimental results show that the proposed algorithm had good performances in terms of imperceptibility and watermarking capacity compared with advanced steganography algorithms. The proposed algorithm improved the PSNR by 0.17 on average with the same watermark capacity.


Assuntos
Redes Neurais de Computação , Análise de Ondaletas , Algoritmos , Registros , Segurança Computacional
9.
Angew Chem Int Ed Engl ; 62(49): e202311460, 2023 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-37707882

RESUMO

Organic electrode materials (OEMs), valued for their sustainability and structural tunability, have been attracting increasing attention for wide application in sodium-ion batteries (SIBs) and other rechargeable batteries. However, most OEMs are plagued with insufficient specific capacity or poor cycling stability. Therefore, it's imperative to enhance their specific capacity and cycling stability through molecular design. Herein, we designed and synthesized a heteroaromatic molecule 2,3,8,9,14,15-hexanol hexaazatrinaphthalene (HATN-6OH) by the synergetic coupling of catechol (the precursor of ortho-quinone)/ortho-quinone functional groups and HATN conjugated core structures. The abundance of catechol/ortho-quinone and imine redox-active moieties delivers a high specific capacity of nine-electron transfer for SIBs. Most notably, the π-π interactions and intermolecular hydrogen bond forces among HATN-6OH molecules secure the stable long-term cycling performance of SIBs. Consequently, the as-prepared HATN-6OH electrode exhibited a high specific capacity (554 mAh g-1 at 0.1 A g-1 ), excellent rate capability (202 mAh g-1 at 10 A g-1 ), and stable long-term cycling performance (73 % after 3000 cycles at 10 A g-1 ) in SIBs. Additionally, the nine-electron transfer mechanism is confirmed by systematic density functional theory (DFT) calculation, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and Raman analysis. The achievement of the synergetic coupling of the redox-active sites on OEMs could be an important key to the enhancement of SIBs and other metal-ion batteries.

10.
Small ; 18(9): e2105331, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34913585

RESUMO

Interfacial engineering and elemental doping are the two parameters to enhance the catalytic behavior of cobalt nitrides for the alkaline hydrogen evolution reaction (HER). However, simultaneously combining these two parameters to improve the HER catalytic properties of cobalt nitrides in alkaline media is rarely reported and also remains challenging in acidic media. Herein, it is demonstrated that high-valence non-3d metal and non-metal integration can simultaneously achieve Co-based nitride/oxide interstitial compound phase boundaries on stainless steel mesh (denoted Mo-Co5.47 N/N-CoO) for efficient HER in alkaline and acidic media. Density functional theory (DFT) calculations show that the unique structure does not only realize multi-active sites, enhanced water dissociation kinetics, and low hydrogen adsorption free energy in alkaline media, but also enhances the positive charge density of hydrogen ions (H+ ) to effectively allow H+ to receive electrons from the catalysts surface toward promoting the HER in acidic media. As a result, the as-prepared Mo-Co5.47 N/N-CoO demands HER overpotential of -28 mV@10 mA cm-2 in an alkaline medium, and superior to the commercial Pt/C at a current density > 44 mA cm-2 in acidic medium. This work paves a useful strategy to design efficient cobalt-based electrocatalysts for HER and beyond.

11.
Small ; 18(10): e2105761, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35266313

RESUMO

Rechargeable aqueous zinc-ion batteries (ZIBs) are promising in stationary grid energy storage due to their advantages in safety and cost-effectiveness, and the search for competent cathode materials is one core task in the development of ZIBs. Herein, the authors design a 2D heterostructure combining amorphous vanadium pentoxide and electrochemically produced graphene oxide (EGO) using a fast and scalable spray drying technique. The unique 2D heterostructured xerogel is achieved by controlling the concentration of EGO in the precursor solution. Driven by the improved electrochemical kinetics, the resultant xerogel can deliver an excellent rate capability (334 mAh g-1 at 5 A g-1 ) as well as a high specific capacity (462 mAh g-1 at 0.2 A g-1 ) as the cathode material in ZIB. It is also shown that the coin cell constructed based on spray-dried xerogel can output steady, high energy densities over a broad power density window. This work provides a scalable and cost-effective approach for making high performance electrode materials from cheap sources through existing industrialized materials processing.

12.
Sensors (Basel) ; 22(20)2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36298196

RESUMO

Deep learning has become an essential technique in image steganography. Most of the current deep-learning-based steganographic methods process digital images in the spatial domain. There are problems such as limited embedding capacity and unsatisfactory visual quality. To improve capacity-distortion performance, we develop a steganographic method from the frequency-domain perspective. We propose a module called the adaptive frequency-domain channel attention network (AFcaNet), which makes full use of the frequency features in each channel by a fine-grained manner of assigning weights. We apply this module to the state-of-the-art SteganoGAN, forming an Adaptive Frequency High-capacity Steganography Generative Adversarial Network (AFHS-GAN). The proposed neural network enhances the ability of high-dimensional feature extraction through overlaying densely connected convolutional blocks. In addition to this, a low-frequency loss function is introduced as an evaluation metric to guide the training of the network and thus reduces the modification of low-frequency regions of the image. Experimental results on the Div2K dataset show that our method has a better generalization capability compared to the SteganoGAN, with substantial improvement in both embedding capacity and stego-image quality. Furthermore, the embedding distribution of our method in the DCT domain is more similar to that of the traditional method, which is consistent with the prior knowledge of image steganography.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador , Processamento de Imagem Assistida por Computador/métodos , Redes Neurais de Computação
13.
Angew Chem Int Ed Engl ; 61(41): e202206152, 2022 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-35768337

RESUMO

Bioinspired asymmetric nanofluidic ion channels with ionic diode behavior that can boost the osmotic energy (so-called blue energy) conversion are highly desirable, especially if they can be easily constructed and modified. Two-dimensional (2D) metal carbides and nitrides, known as MXenes, combine hydrophilic surfaces and tunable surface charge properties, providing a shortcut to prepare asymmetric nanofluidic ion channels. Here, we report a mechanically robust, flexible, and scale-up-friendly asymmetric Ti3 C2 Tx MXene-based ionic diode membrane with a highly rectified current and demonstrate its potential use in reverse electrodialysis osmotic energy conversion. Under the salinity gradient of synthetic seawater and river water, our ionic diode membrane-based generator's power density is 8.6 W m-2 and up to 17.8 W m-2 at a 500-fold salinity gradient, outperforming the state-of-the-art membranes. The design of MXene-based ionic diode-type membrane provides a facile and general strategy in developing large-scale 2D nanofluidics and selective ion transport.


Assuntos
Salinidade , Titânio , Íons , Osmose , Água
14.
Angew Chem Int Ed Engl ; 61(51): e202213296, 2022 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-36280592

RESUMO

Not only high efficiency but also high selectivity of the electrocatalysts is crucial for high-performance, low-cost, and sustainable energy storage applications. Herein, we systematically investigate the edge effect of carbon-supported single-atom catalysts (SACs) on oxygen reduction reaction (ORR) pathways (two-electron (2 e- ) or four-electron (4 e- )) and conclude that the 2 e- -ORR proceeding over the edge-hosted atomic Co-N4 sites is more favorable than the basal-plane-hosted ones. As such, we have successfully synthesized and tuned Co-SACs with different edge-to-bulk ratios. The as-prepared edge-rich Co-N/HPC catalyst exhibits excellent 2 e- -ORR performance with a remarkable selectivity of ≈95 % in a wide potential range. Furthermore, we also find that oxygen functional groups could saturate the graphitic carbon edges under the ORR operation and further promote electrocatalytic performance. These findings on the structure-property relationship in SACs offer a promising direction for large-scale and low-cost electrochemical H2 O2 production via the 2 e- -ORR.

15.
Sensors (Basel) ; 21(19)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34640870

RESUMO

This paper proposes a screen-shooting resilient watermarking scheme via learned invariant keypoints and QT; that is, if the watermarked image is displayed on the screen and captured by a camera, the watermark can be still extracted from the photo. A screen-shooting resilient watermarking algorithm should meet the following two basic requirements: robust keypoints and a robust watermark algorithm. In our case, we embedded watermarks by combining the feature region filtering model to SuperPoint (FRFS) neural networks, quaternion discrete Fourier transform (QDFT), and tensor decomposition (TD). First we applied FRFS to locate the embedding feature regions which are decided by the keypoints that survive screen-shooting. Second, we structured watermark embedding regions centered at keypoints. Third, the watermarks were embedded by the QDFT and TD (QT) algorithm, which is robust for capturing process attacks. In a partial shooting scenario, the watermark is repeatedly embedded into different regions in an image to enhance robustness. Finally, we extracted the watermarks from at least one region at the extraction stage. The experimental results showed that the proposed scheme is very robust for camera shooting (including partial shooting) different shooting scenarios, and special attacks. Moreover, the efficient mechanism of screen-shooting resilient watermarking could have propietary protection and leak tracing applications.


Assuntos
Algoritmos , Interpretação de Imagem Assistida por Computador , Redes Neurais de Computação
16.
Angew Chem Int Ed Engl ; 60(12): 6326-6332, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33354840

RESUMO

Dual-ion batteries (DIBs) inherently suffer from limited energy density. Proposed here is a strategy to effectively tackle this issue by employing locally ordered graphitized carbon (LOGC) cathodes. Quantum mechanical modeling suggests that strong anion-anion repulsions 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 interactions, while disordered carbons not only interconnect the dispersed nanographite but also partially buffer severe anion-anion repulsion and offer extra capacitive anion storage sites. As a proof-of-concept, ketjen black (KB) with LOGC was used 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.

17.
Angew Chem Int Ed Engl ; 60(34): 18830-18837, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34142765

RESUMO

Electronic structure engineering on electrode materials could bring in a new mechanism to achieve high energy and high power densities in sodium ion batteries. Herein, we design and create Co vacancies at the interface of atomically thin CoSe2 /graphene heterostructure and obtain Co1-x Se2 /graphene heterostructure electrode materials that facilitate significant Na+ intercalation pseudocapacitance. Density functional theory (DFT) calculation suggests that the Na+ adsorption energy is dramatically increased, and the Na+ diffusion barrier is remarkably reduced due to the introduction of Co vacancy. The optimized electrode delivers a superior capacity of 673.6 mAh g-1 at 0.1 C, excellent rate capability of 576.5 mAh g-1 at 2.0 C and ultra-long life up to 2000 cycles. Kinetics analysis indicates that the enhanced Na+ storage is mainly attributed to the intercalation pseudocapacitance induced by Co vacancies. This work suggests that the creation of cation vacancy could bestow heterostructured electrode materials with pseudocapacitive Na+ intercalation for high-capacity and high-rate energy storage.

18.
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.

19.
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.

20.
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.

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