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1.
Herein, we present a simple and rapid method to synthesize porous silicon/carbon microtube composites (PoSi/CMTs) by adopting a unique configuration of acid etching solution. The CMTs can act as both conductive agent and buffer for Si volume change during the charge and discharge process. The highly reversible capacity and excellent rate capability can be ascribed to the structure, where porous silicon powders are wrapped by a network of interwoven carbon microtubes. The composites show specific capacities of more than 1712 mA h g−1 at a current density of 100 mA g−1, 1566 mA h g−1 at 200 mA g−1, 1407 mA h g−1 at 400 mA g−1, 1177 mA h g−1 at 800 mA g−1, 1107 mA h g−1 at 1000 mA g−1, 798 mA hg−1 at 2000 mA g−1, and 581 mA h g−1 at 3000 mA g−1 and maintain a value of 1127 mA h g−1 after 100 cycles at a current density of 200 mA g−1. Electrochemical impedance spectroscopy (EIS) measurements prove that charge transfer resistance of PoSi/CMT composites is smaller than that of pure PoSi. In this study, we propose a quick, economical and feasible method to prepare silicon-based anode materials for lithium-ion batteries.

We added additives to the acid etching solution and prepared the silicon/carbon microtubes composites using a simple and fast method.  相似文献   

2.
Significant research efforts, mostly experimental, have been devoted to finding high-performance anode materials for lithium-ion and potassium-ion batteries; both graphitic carbon-based and carbon nanotube-based materials have been generating huge interest. Here, first-principles calculations are performed to investigate the possible effects of doping defects and the varying tube diameter of carbon nanotubes (CNTs) on their potential for battery applications. Both adsorption and migration of Li and K are studied for a range of pristine and nitrogen-doped CNTs, which are further compared with 2D graphene-based counterparts. We use detailed electronic structure analyses to reveal that different doping defects are advantageous for carbon nanotube-based and graphene-based models, as well as that curved CNT walls help facilitate the penetration of potassium through the doping defect while showing a negative effect on that of lithium.

First-principles simulations reveal atomistic mechanisms for adsorption and migration of lithium and potassium on nitrogen-doped carbon nanotubes.  相似文献   

3.
Nitrogen self-doped carbon was synthesized by hydrothermal and microwave calcination using polyacrylonitrile as a carbon source and nitrogen source. This method dramatically reduces the material preparation time while improving the electrochemical performance of amorphous carbon. X-ray photoelectron spectroscopy (XPS) analyses reveal that the pyridine nitrogen content is increased and the graphitized nitrogen disappeared in an amorphous carbon block. This indicates that the nitrogen doping sites of the amorphous carbon block can be modulated by the hydrothermal method. Microscopic observations show that the nitrogen self-doped carbon is nano-carbon spheres and carbon micron block. The self-doped nitrogen micron carbon block exhibits excellent cyclability and ultra-high rate capacity. When cycled at 0.5 A g−1, the discharge capacity remains 356.6 mA h g−1 after 1000 cycles. Even cycled at 5 A g−1, the rate capacity was maintained at 183.3 mA h g−1 after 300 cycles. The defects produced by self-doped pyridine nitrogen, not only improved the reactivity and electronic conductivity but also enhanced lithium-ion diffusion kinetics.

Nitrogen doping sites can be modulated by the hydrothermal method. The defects produced by self-doped pyridine nitrogen, not only improved the reactivity and electronic conductivity but also enhanced lithium-ion diffusion kinetics.  相似文献   

4.
The C@GQD composite was prepared by the combination of metal–organic framework (ZIF-8)-derived porous carbon and graphene quantum dots (GQDs) by a simple method. The resulting composite has a high specific surface area of 668 m2 g−1 and involves numerous micro- and mesopores. As a supercapacitor electrode, the material showed an excellent double-layer capacitance and a high capacity retention of 130 F g−1 at 2 A g−1. The excellent long-term stability was observed even after ∼10 000 charge–discharge cycles. Moreover, the composite as an anode material for a lithium-ion battery exhibited a good reversible capacity and outstanding cycle stability (493 mA h g−1 at 100 mA g−1 after 200 cycles). The synergistic effect of a MOF-derived porous carbon and GQDs was responsible for the improvement of electrochemical properties.

The C@GQD composite was prepared by the combination of metal–organic framework (ZIF-8)-derived porous carbon and graphene quantum dots (GQDs) by a simple method.  相似文献   

5.
A facile synthesis of perovskite-type CeMnO3 nanofibers as a high performance anode material for lithium-ion batteries was demonstrated. The nanofibers were prepared by the electrospinning technique. The characterization of CeMnO3 nanofibers was carried out by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. SEM images manifested nanofibers with a diameter of 470 nm having a rough surface with a porous structure. TEM images were consistent with the observations from the SEM images. The electrochemical properties of CeMnO3 perovskite in lithium-ion batteries were investigated. The CeMnO3 anode exhibited a discharge capacity of 2159 mA h g−1 with a coulombic efficiency of 93.79%. In addition, a high cycle stability and a capacity of 276 mA h g−1 at the current density of 1000 mA g−1 can be effectively maintained due to the high Li+ conductivity in the CeMnO3 anode. This study could provide an efficient and potential application of perovskite-type CeMnO3 nanofibers in lithium-ion batteries.

A facile synthesis of perovskite-type CeMnO3 nanofibers as a high performance anode material for lithium-ion batteries was demonstrated.  相似文献   

6.
Nanostructured ZnCo2O4 anode materials for lithium-ion batteries (LIBs) have been successfully prepared by a two-step process, combining facile and concise electrospinning and simple post-treatment techniques. Three different structured ZnCo2O4 anodes (nanoparticles, nanotubes and nanowires) can be prepared by simply adjusting the ratio of metallic salt and PVP in the precursor solutions. Charge–discharge tests and cyclic voltammetry (CV) have been conducted to evaluate the lithium storage performances of ZnCo2O4 anodes, particularly for ZnCo2O4 nanotubes obtained from a weight ratio 2 : 4 of metallic salt and PVP polymer in the precursor solution. Remarkably, ZnCo2O4 nanotubes exhibit high specific capacity, good rate property, and long cycling stability. Reversible capacity is still maintained at 1180.8 mA h g−1 after 275 cycles at a current density of 200 mA g−1. In case of rate capability, even after cycling at the 2000 mA g−1 current density, the capacity could recover to 684 mA h g−1. The brilliant electrochemical properties of the ZnCo2O4 anodes make them promising anodes for LIBs and other energy storage applications.

ZnCo2O4 nanoparticles, nanotubes, and nanofibers can be controllably prepared by simply tuning the weight ratios of metallic salts and PVP polymer in the precursor solution.  相似文献   

7.
A comparatively facile and ecofriendly process has been developed to synthesize porous carbon materials from Camellia oleifera shells. Potassium carbonate solution (K2CO3) impregnation is introduced to modify the functional groups on the surface of Camellia oleifera shells, which may play a role in promoting the development of pore structure during carbonization treatment. Moreover, a small amount of naturally embedded nitrogen and sulfur in the Camellia oleifera shells can also bring about the formation of pores. The Camellia oleifera shell-derived carbon has a large specific surface area of 1479 m2 g−1 with a total pore volume of 0.832 cm3 g−1 after being carbonized at 900 °C for 1 h. Furthermore, when used as an anode for lithium-ion batteries, the sample shows superior electrochemical performance with a specific capacity of 483 mA h g−1 after 100 cycles measured at 200 mA g−1 current density. Surprisingly, the specific capacity is even gradually increased with cycling. In addition, this sample exhibits almost 100% retention capacity after 250 cycles at a current density of 200 mA g−1.

Bio-waste Camellia oleifera shells (COS) are converted into porous carbon by a two-step method.  相似文献   

8.
TiO2 has been a promising anode material for sodium-ion batteries because it is low-cost and environment-friendly. However, its electrochemical performance at high rates is still not acceptable. Herein, we synthesized a TiO2/C nanofiber material by the electrospinning method, and introduced air plasma treatments to modify the obtained material. Characterization results indicate that after the plasma treatments, the C fibers may have reacted with the plasma, and the surface areas of the nanofibers are increased. Electrochemical tests show this plasma treatment may be beneficial to the rate performance. The TiO2/C nanofiber with plasma treatment could deliver a high redox capacity of 191 mA h g−1 after 500 cycles at a very high rate of 10C (3300 mA g−1). The superior effects of the plasma treatment on the rate performance may provide new insights for developing better materials for practical sodium-ion batteries.

Plasma treatment greatly improves the rate capability of TiO2/C nanofibers.  相似文献   

9.
SnO2/graphene nanocomposite was successfully synthesized by a facile sonochemical method from SnCl2 and graphene oxide (GO) precursors. In the sonochemical process, the Sn2+ is firstly dispersed homogeneously on the GO surface, then in situ oxidized to SnO2 nanoparticles on both sides of the graphene nanosheets (RGO) obtained by the reduction of GO under continuous ultrasonication. Graphene not only provides a mechanical support to alleviate the volume changes of the SnO2 anode and prevent nanoparticle agglomeration, but also serves as a conductive network to facilitate charge transfer and Li+ diffusion. When used as a lithium ion battery (LIB) anode, the SnO2/graphene nanocomposite exhibits significantly improved specific capacity (1610 mA h g−1 at 100 mA g−1), good cycling stability (retaining 87% after 100 cycles), and competitive rate performance (273 mA h g−1 at 500 mA g−1) compared to those of bare SnO2. This sonochemical method can be also applied to the synthesis of other metal-oxide/graphene composites and this work provides a large-scale preparation route for the practical application of SnO2 in lithium ion batteries.

SnO2/graphene nanocomposite was successfully synthesized by a facile sonochemical method from SnCl2 and graphene oxide (GO) precursors.  相似文献   

10.
Cheng Chang  Sha Yin  Jun Xu 《RSC advances》2020,10(23):13662
In this study, the adsorption of Li atoms on various types of doped graphene with substituents, including boron, nitrogen, sulfur and silicon atoms, has been theoretically investigated by first-principles calculations, based on the density functional theory. We discovered that the boron-doped graphene had a greatly enhanced Li-binding energy than those of graphene with other doped atoms as well as pristine graphene, which is helpful in preventing the Li atoms from clustering during charging. The Li atom preferred to be close to the doped B or Si atom, but farther away from the substituted N and S atoms, with different stable adsorption sites. This demonstrated the different chemical interactions between the Li atoms and the distinct dopants in graphene, which was confirmed by the electron density and charge transfer analysis. However, it was found that the introduction of dopant atoms in-plane with graphene reduced the mechanical strength of the graphene anode throughout the uniaxial tension simulations. Lastly, the effect of strain on the adsorption energy of the Li atoms on doped graphene was studied, and the results illustrated that tensile strain enhances the interactions between the Li atoms and the graphene anode. These results provide theoretical guidance for the discovery and fabrication of high-energy-density anode materials with desired mechanical properties.

The adsorption of Li atoms on various types of doped graphene with substituents, including boron, nitrogen, sulfur and silicon atoms, has been theoretically investigated by first-principles calculations, based on the density functional theory.  相似文献   

11.
Manganese oxalates with different structures and morphologies were prepared by the precipitation method in a mixture of dimethyl sulfoxide (DMSO) and proton solvents. The proton solvents play a key role in determining the structures and morphologies of manganese oxalate. Monoclinic MnC2O4·2H2O microrods are prepared in H2O-DMSO, while MnC2O4·H2O nanorods and nanosheets with low crystallinity are synthesized in ethylene glycol-DMSO and ethanol-DMSO, respectively. The corresponding dehydrated products are mesoporous MnC2O4 microrods, nanorods, and nanosheets, respectively. When used as anode material for Li-ion batteries, mesoporous MnC2O4 microrods, nanorods, and nanosheets deliver a capacity of 800, 838, and 548 mA h g−1 after 120 cycles at 8C, respectively. Even when charged/discharged at 20C, mesoporous MnC2O4 nanorods still provide a reversible capacity of 647 mA h g−1 after 600 cycles, exhibiting better rater performance and cycling stability. The electrochemical performance is greatly influenced by the synergistic effect of surface area, morphology, and size. Therefore, the mesoporous MnC2O4 nanorods are a promising anode material for Li-ion batteries due to their good cycle stability and rate performance.

Manganese oxalates with different structures and morphologies were prepared by the precipitation method in a mixture of dimethyl sulfoxide (DMSO) and proton solvents.  相似文献   

12.
Emerging technologies demand a new generation of lithium-ion batteries that are high in power density, fast-charging, safe to use, and have long cycle lives. This work reports charging rates and specific capacities of TiO2(B)/N-doped graphene (TNG) composites. The TNG composites were prepared by the hydrothermal method in various reaction times (3, 6, 9, 12, and 24 h), while the N-doped graphene was synthesized using the modified Hummer''s method followed by a heat-treatment process. The different morphologies of TiO2 dispersed on the N-doped graphene sheet were confirmed as anatase-nanoparticles (3, 6 h), TiO2(B)-nanotubes (9 h), and TiO2(B)-nanorods (12, 24 h) by XRD, TEM, and EELS. In electrochemical studies, the best battery performance was obtained with the nanorods TiO2(B)/N-doped graphene (TNG-24h) electrode, with a relatively high specific capacity of 500 mA h g−1 at 1C (539.5 mA g−1). In long-term cycling, excellent stability was observed. The capacity retention of 150 mA h g−1 was observed after 7000 cycles, at an ultrahigh current of 50C (27.0 A g−1). The synthesized composites have the potential for fast-charging and have high stability, showing potential as an anode material in advanced power batteries for next-generation applications.

The TiO2-bronze/nitrogen-doped graphene nanocomposites have the potential for fast-charging and have high stability, showing potential as an anode material in advanced power batteries for next-generation applications.  相似文献   

13.
Porous nanostructures have been proposed a promising strategy to improve the electrochemical performance of Si materials as anodes of lithium-ion batteries (LIBs). However, expensive raw materials and the tedious preparation processes hinder their widespread adoption. In this work, silicon micron cages (SMCs) have been synthesized in molten AlCl3 through using spherical aluminum particles as a sacrificial template, and the earth-abundant and low-cost natural halloysite clay as a precursor. The aluminum spheres (1–3 μm) not only act as a sacrificial template but also facilitate the formation of silicon branches, which connect together to form SMCs. As anodes for LIBs, the SMC electrode exhibits a high reversible capacity of 1977.5 mA h g−1 after 50 cycles at a current density of 0.2 A g−1, and 1035.1 mA h g−1 after 300 cycles at a current density of 1.0 A g−1. The improved electrochemical performance of SMCs could be ascribed to the micron cage structure, providing abundant buffering space and mesopores for Si expansion. This promising method is expected to offer a pathway towards the scalable application of Si-based anode materials in the next-generation LIB technology.

(1) Silicon micron cages (SMCs) was synthesized using natural halloysite as precursor. (2) The electrochemical performance of SMCs as anode materials of lithium-ion batteries can be improved for the micron cage structure.  相似文献   

14.
ZnCo2O4 has become one of the most widely used anode materials due to its good specific capacity, cost-efficiency, high thermal stability and environmental benignity. However, its poor conductivity and cycle stability have limited its practical application in lithium-ion batteries. To overcome these issues, we constructed a 3D nanoflower composite material (ZnCo2O4@C3N4-B) by combining ZnCo2O4 as a framework and B-doped g-C3N4 (g-C3N4-B) as a new carbon source material via a simple hydrothermal method. ZnCo2O4@C3N4-B exhibited exceptional specific capacitance of 919.76 mA h g−1 after 500 cycles at 0.2 A g−1 and a long-term capacity retention of 97.8% after 1000 cycles at 2 A g−1. The high reversible capacity, long cycling life and good rate performance could be attributed to the 3D interconnected architecture and doping of g-C3N4-B. This work provides a simple and general strategy to design high-performance anode materials for lithium-ion batteries to meet the needs of practical applications.

ZnCo2O4 has become one of the most widely used anode materials due to its good specific capacity, cost-efficiency, high thermal stability and environmental benignity.  相似文献   

15.
Titanium niobium oxides (TNOs), benefitting from their large specific capacity and Wadsley–Roth shear structure, are competitive anode materials for high-energy density and high-rate lithium-ion batteries. Herein, carbon and oxygen vacancy co-modified TiNb6O17 (A-TNO) was synthesized through a facile sol–gel reaction with subsequent heat treatment and ball-milling. Characterizations indicated that A-TNO is composed of nanosized primary particles, and the carbon content is about 0.7 wt%. The nanoparticles increase the contact area of the electrode and electrolyte and shorten the lithium-ion diffusion distance. The carbon and oxygen vacancies decrease the charge transfer resistance and enhance the Li-ion diffusion coefficient of the obtained anode material. As a result of these advantages, A-TNO exhibits excellent rate performance (208 and 177 mA h g−1 at 10C and 20C, respectively). This work reveals that A-TNO possesses good electrochemical performance and has a facile preparation process, thus A-TNO is believed to be a potential anode material for large-scale applications.

Carbon and oxygen vacancy co-modified TiNb6O17 is synthesized through a facile sol–gel reaction. It possesses good electrochemical performance, thus is believed to be a potential anode material for large-scale applications.  相似文献   

16.
Silicon, with advantages such as high theoretical capacity and relatively low working potential, has been regarded as promising when it is used for lithium-ion battery anodes. However, its practical application is impeded by the intrinsic low electrical conductivity and the dramatic volume change during the lithiation/delithiation process, which leads to a rapid capacity fading of the electrode. In this regard, we design silicon nanoparticles homogeneously coated with a phenolic resin-based carbon layer as a core–shell nanocomposite via a facile self-assembly method followed by carbonization. The surrounding carbon shell, confirmed by transmission electron microscopy and Raman spectroscopy, is not only beneficial to the formation of a stable solid electrolyte interface film, but the electrical conductivity of the electrode is also enhanced. A high and stable specific capacity of nearly 1000 mA h g−1 is achieved at C/3 after 200 cycles with a coulombic efficiency of >99.6%. The entire synthesis process is quite simple and easy to scale up, thus having great potential for commercial applications.

A self-assembled silicon/phenolic resin-based carbon core–shell nanocomposite is reported, which exhibits a high and stable reversible capacity and good rate capability.  相似文献   

17.
With the increased demand for high-rate performance Li-ion batteries, it is necessary to find available methods to improve the rate properties of SnO2 electrodes. It is noteworthy that doping was considered to be a feasible means. The electronic structures and diffusion energy barriers of Ni-doped and Ni–N co-doped SnO2 were calculated based on density functional theory. The results estimated that the energy gaps of Ni-doped and Ni–N co-doped SnO2 are 1.07 eV and 0.94 eV, which both are smaller than the value of 2.08 eV of SnO2. These exhibit that the conduction properties of SnO2 can be enhanced by doping with the Ni or Ni–N atoms. Moreover, the diffusion properties of Li can also be improved by doping with Ni–N atoms due to the diffusion energy barrier of Li from the B to C point for Ni–N co-doped SnO2 being 0.12 eV smaller than the value of 0.24 eV for the pristine SnO2. Meanwhile, the diffusion energy barriers of Li along other pathways for Ni–N co-doped SnO2 are almost the same as 0.24 eV for SnO2. These results show that both the electronic and ionic conductivity of SnO2 can be enhanced by Ni–N co-doping, which provides a theoretical explanation to promote the rate properties of SnO2 by Ni–N co-doping as anode materials for Li-ion batteries.

Energy barriers of Li, where red, green and yellow curves represent diffusion energy barriers of Li in the pure, Ni-doped, and Ni–N co-doped SnO2, respectively.  相似文献   

18.
The polymers based on thiophene armed triazine and different thiophene derivatives including thiophene (Th), thieno[3,2-b]thiophene (TT), dithieno[3,2-b:2′,3′-d]thiophene (DTT) or thieno[2′,3'':4,5]thieno[3,2-b]thieno[2,3-d]thiophene (TTTT) are synthesized through a Stille coupling reaction. By introducing thiophene derivatives with increasing sizes as the linkage units (from thiophene, DT to DTT, TTTT), the band gaps (Eg) of the resultant polymers decrease continuously. Then the composite materials (polymer@C) between polymers and Vulcan XC-72 carbon are prepared by in situ polymerization to test their electrochemical performances in lithium ion batteries. The synthesized composites show distinct morphologies due to the different linkage units of thiophene or fused cyclothiophene derivatives and the cross-linked structure can be found in composites with the longer thiophene derivatives (bridging molecules) like PTT-3@C and PTT-4@C, which are expected to be beneficial to improve the performances of the electrode materials. The specific capacities of the composites are 495 mA h g−1, 671 mA h g−1, 707 mA h g−1, and 772 mA h g−1 for PTT-1@C, PTT-2@C, PTT-3@C and PTT-4@C at a current density of 100 mA g−1, respectively. In particular, benefiting from the enlarged conjugation length and planarity of the linkage units, the conjugated microporous polymers could deliver continuously improved capacities.

Four different kinds of conjugated porous polymers PTTs were synthesized and their composites with carbon material were used as the electrode materials for LIBs.  相似文献   

19.
Metal–organic frameworks (MOFs) with efficient surface and structural properties have risen as a distinctive class of porous materials through the last few decades, which has enabled MOFs to gain attention in a wide range of applications like drug delivery, gas separation and storage, catalysis and sensors. Likewise, they have also emerged as efficient active materials in energy storage devices owing to their remarkable conducting properties. Metal–organic frameworks (MOFs) have garnered great interest in high-energy-density rechargeable batteries and super-capacitors. Herein the study presents their expanding diversity, structures and chemical compositions which can be tuned at the molecular level. It also aims to evaluate their inherently porous framework and how it facilitates electronic and ionic transportation through the charging and discharging cycles of lithium-ion batteries. In this review we have summarized the various synthesis paths to achieve a particular metal–organic framework. This study focuses mainly on the implementation of metal–organic frameworks as efficient anode and cathode materials for lithium-ion batteries (LIBs) with an evaluation of their influence on cyclic stability and discharge capacity. For this purpose, a brief assessment is made of recent developments in metal–organic frameworks as anode or cathode materials for lithium-ion batteries which would provide enlightenment in optimizing the reaction conditions for designing a MOF structure for the battery community and electrochemical energy storage applications.

In this review article, a comprehensive insight is given into current progress of electrochemical evaluation of MOFs based material as efficient anode and cathode materials for LIBs.  相似文献   

20.
Triblock copolymer polydopamine-polyacrylic-polyoxyethylene (PDA-PAA-PEO) with excellent performance as a binder for silicon anodes was synthesized. Its structure was confirmed by 1H-NMR, FTIR and UV-vis spectroscopy. Results of electrochemical measurements indicated that a silicon anode based on PDA-PAA-PEO binder exhibited excellent cycle performance with a reversible capacity of 1597 mA h g−1 after 200 cycles at a current density of 0.5 C, much better than that of an electrode based on a polyvinylidene-fluoride binder. Improvement of the cycle performance and reversible capacity for silicon anodes could be attributed to the strong adhesive and high ion conductivity of PDA-PAA-PEO.

Triblock copolymer polydopamine-polyacrylic-polyoxyethylene with strong adhesion as a novel binder enhance the cycle performance of silicon anode.  相似文献   

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