JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Xian Zhang,Yuhang Yang,Simin Xia,Zhengru Huang,Jiage Yu,Yuqiang Pi,Feng Wang,Yu Ding
Si possesses a high theoretical specific capacity as anode material for Li-ion batteries. However, it has poor electrical conductivity and severe volume effect during charge-discharge processes, resulting in substantial internal resistance and significantly reduced available capacity. These issues can be greatly mitigated by encapsulating Si nanoparticles within a carbonous material. Hence, network precursors are synthesised herein to encapsulate Si nanoparticles by in situ polymerisation of acrylic acid and melamine. After freeze-drying, the precursors are pyrolysed under Ar atmosphere to obtain homogeneous N-rich porous Si@SiO x /NC composites. A fibrous network structure is acquired by using appropriate amounts of polyacrylic acid and Si. Such a structure provides an outstanding electron transmission network and effectively buffers the volume change of Si to maintain a stable electrode structure. The results show that when the content of Si nanoparticles in the composite is 35.2 wt%, the prepared Si@SiO x /NC−2 composite has abundant micropores (267.90 m 2 g −1 ) and mesopores (17.48 m 2 g −1 ). The material shows an initial discharge-specific capacity of 1833.6 mAh g −1 and Coulombic efficiency of 65%. After 150 cycles at 0.1 A g −1 , the discharge-specific capacity is still as high as 922.8 mAh g −1 . The excellent electrochemical performance of the Si@SiO x /NC composites is due to the three-dimensional conductive structure. The unique construction could play an important role in expanding the commercial application of Si-based anode materials in Li-ion batteries.
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Jiajin Zhong,Na Li,Xiaoxuan Xu,Limin Wei,Huijian Liu,Huijuan Li,Zheng Fang,Haifeng Bao
High temperature thermally stable fiber materials with flexibility are expected to be applicable to severe conditions. In this article, ZrO 2 /Si–C–O ceramic fibers have been synthesized by the sol-gel process combined with the electrospinning technique. We focus on the changes of composition, structure and morphology with the increasing heat treatment temperature. More importantly, the effects of ZrO 2 crystalline phase transformation on mechanical property of ZrO 2 /Si–C–O ceramic fibers have been investigated. The results show that the increased temperature can lead to an increase of the fiber diameter and grain size, as well as the transformation of ZrO 2 phase. It is also found that the ZrO 2 /Si–C–O ceramic fibers possess refined crystalline grain and improved mechanical properties at a heat treatment temperature of 800 °C, which is mainly due to the fact that the amorphous Si–C–O phase containing free carbon facilitates the refinement of the crystalline grain, and the ZrO 2 in the tetragonal structure improves the flexibility of ceramic fibers. Furthermore, the obtained fibers exhibit excellent thermal stability up to 1300 °C, therefore they have broad application prospect in high temperature environment.
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ENERGY & FUELS
·
2023
·
IF 5.3
Xingyu Zhang,Luqi Wang,Tianye Zheng,Kwok-Ho Lam
This work successfully introduced the different ratios of metallic Cr into micrometer Si bulk via a high-energy ball-milling method to synthesize nanostructured Si/CrSi2 alloy anodes with enhanced electrochemical performance in lithium-ion batteries (LIBs). This study demonstrated that the in situ-formed CrSi2 could effectively suppress the generation of crystalline Li3.75Si in the lithiation process, dilute Si’s volume expansion, and improve electronic conductivity. Concretely, Si85Cr15 displayed an outstanding reversible volumetric capacity of ∼1400 A h·L–1 and 100-cycle capacity retention at 0.2 C of 90.1% with an average Coulombic efficiency of 99.46%. Moreover, another advantage of Si85Cr15 is good compatibility with the carbon-coating treatment at 800 °C by virtue of the reinforced thermal stability derived from a high melting point of CrSi2. The homogeneous distribution of Si and metal silicide crystallites was better maintained in Si85Cr15@c-PDA compared to our previously annealed Si–Cu3Si–NiSi2 alloys at the same temperature. Correspondingly, the cycle stability and rate capability of Si85Cr15@c-PDA were further improved with a capacity retention of 93.1/90.6% at 0.2/0.5 C (100/200 cycles) and 40% at 2 C, respectively. The excellent electrochemical performance indicates that Si/CrSi2 alloys may be prospective candidates as compositions in the carbon-coated anode materials for industrialized LIBs.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Xilei Xie,Peng Xiao,Liang Pang,Peng Zhou,Yangjie Li,Jian Luo,Jiangzhi Xiong,Yang Li
The low cost and high performance via a simple way of fabrication are considerable challenges for Si-based anode in the application of lithium-ion batteries. In this study, we synthesize a novel free-standing Si/C anode, consisting of yolk (Si)-shell (amorphous carbon) nanoparticles and carbon nanofibers (denoted as Si@void@C/CNFs), via a facile route of template removal and electrospun. The designed yolk-shell structure help buffer the volume expansion of silicon during the discharge/charge cycles, and the intertwined CNFs are conducive to electron fast transmission and guarantee structural integrity. As expected, with a low Si content (∼23 wt%), the self-supporting electrode of Si@void@C/CNFs exhibits a high specific capacity of ∼627.5 mAh g −1 as well as 69.3% capacity retention at 0.1 A g −1 after 100 cycles, better than Si@C/CNFs (20%) and Si/CNFs (9.5%) electrodes. The superior performance of Si@void@C/CNFs indicates that it is an attractive anode material for the practical application of Lithium-ion batteries.
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ADVANCED FUNCTIONAL MATERIALS
·
2022
·Vol. 32
·期 40
·2206615
·
IF 19.924
Zeheng Li,Weiting Tang,Yajun Yang,Guoyong Lai,Zheng Lin,Huayan Xiao,Juncheng Qiu,Xiujuan Wei,Shuxing Wu,Zhan Lin
The low initial Coulombic efficiency (ICE) and insufficient cycling lives of silicon (Si)-based anodes seriously hinder their eventual introduction into next-generation high-energy-density lithium–ion batteries (LIBs). Herein, an engineering prelithiation binder strategy based on polyacrylic acid (Li x PAA) is proposed for representative SiO x anodes. The ICEs and cycling lives of SiO x anodes are significantly improved by precisely controlling the lithiation degree of PAA binder. The ICE of the high-loading (3.0 mg cm −2 ) SiO x electrode increases by 10.9% when the Li 0.75 PAA binder replaces the PAA binder. Moreover, the working mechanism of the lithiation binder strategy to improve the electrochemical performances (especially for ICE) is systematically investigated, which is universally applied to other Si anodes such as Si nanoparticles and Si/graphite. This universal binder strategy and proposed working mechanism provide enlightenment on constructing high-ICE, high-energy-density, and long-life Si-based anodes.
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CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Tianxing Gong,Tingyu Li,Lisha Meng,Yadong Chen,Tao Wu,Jingqiu Zhou,Guoxiu Lu,Zhiguo Wang
Native bone is piezoelectric in nature and generates abundant surface charges under mechanical compression, which regulate osteoblast proliferation, differentiation, adhesion, and so on. Poly (vinylidene fluoride) (PVDF) is becoming one of the most popular piezoelectric polymers because of its easy processability and good biocompatibility. Unfortunately, because only the β and γ crystal phases of PVDF have piezoelectricity, post-treatments, for example, polarizing at high temperature, are required to enhance the piezoelectricity of PVDF scaffolds after fabrication. In this study, we reported a phase-separation-hydration method to fabricate a calcium phosphate silicate (CPS)-doped PVDF scaffold. Our method fabricated a better piezoelectric scaffold than native bone without further processing (∼ 3 pC/N vs. 0.7 pC/N). In addition, the scaffold was mechanically compatible (∼ 7 MPa) with the cancellous bone with sufficient porosity (∼ 45%) to facilitate osteoblast infiltration and bone ingrowth. The in vitro biocompatibility analyses proved that the prepared CPS-PVDF scaffold was biocompatible with osteoblast cells and encouraged osteoblast redifferentiation. In conclusion, our results suggest that this CPS-PVDF scaffold is a promising candidate for bone tissue engineering applications.
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Analytical Methods
·
2023
·
IF 3.1
Jun Zhou,Chengyue Zou,Danqun Huo,Chengxiang Chu,Shasha Liu,Mei Yang,Suyi Zhang,Xianfeng Wang,Changjun Hou
Mercury is a heavy metal with extreme toxicity. Thus, it is of significance to develop an effective method for mercury ion detection with high performance. In this study, carbon dots doped with nitrogen and silicon (N,Si/CQDs) were successfully prepared from folic acid and N-[3-(trimethoxysily)propyl]-ethylenediamine. The N,Si/CQDs show an obvious cyan fluorescence of 460 nm with the radiation of 350 nm. The existence of mercury ions induces the fluorescence quenching of N,Si/CQDs due to photoinduced electron transfer, which was applied for the sensitive sensing of Hg(II). More importantly, the practical application of the N,Si/CQD probe was confirmed by measurements of Hg(II) in real samples of lake water, sorghum and rice. In addition, the N,Si/CQD nanoprobe was integrated on a sensing strip for specific detection of Hg(II). Quantitative measurement of Hg(II) was realized by the outstanding linearity between the diameter (or fluorescence intensity) of the fluorescence quenching ring and the concentration of mercury ions. The sensor shows potential for rapid detection with a triple signal readout on-site and represents a larger step towards practical applications.
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高影响因子
Advanced Materials Interfaces
·
2020
·Vol. 7
·期 19
·2000754
·
IF 4.948
Wenzhong Fang,Pan Wang,Zitao Ni,Tao Sun,Chaoyu Xiang,Kun Yue,Rongfei Wang,Jie Yang,Yao Zhou,Chong Wang,Yu Yang
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole injection layer plays an important role in planar Si/PEDOT:PSS heterojunction solar cells (HSCs). Herein, a MoO x mixed aqueous PEDOT:PSS cosolvent is developed and is applied into a Si/PEDOT:PSS solar cell preparation via a time-saving one-step spin-coating method. With an optimal concentration of MoO x dopants, the power conversion efficiency of the device exhibits from 10.26% up to 13.82% with all inherent photovoltaic parameters enhanced. The detailed characterization and analytical results indicate that an advanced electronic property is produced by MoO x dopants and interface optimization caused by synergistic effects from Mo 5+ and Mo 6+ species with PEDOT:PSS, which enhances its interface work function and promotes hole transportation capacity. The result paves a path for exploring efficient Si/PEDOT:PSS HSCs with suitable functional material and a simple solution-processable method.
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高影响因子
Frontiers of Chemical Science and Engineering
·
2020
·Vol. 15
·期 2
·269-278
·
IF 3.552
Hou Yuexin,Li Xiaoyun,Sun Minghui,Li Chaofan,Bakhtiar Syed ul Hasnain,Lei Kunhao,Yu Shen,Wang Zhao,Hu Zhiyi,Chen Lihua,Su Bao-Lian
Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios (Hier-ZSM-5- x , where x = 50, 100, 150 and 200) were synthesized using an ordered mesoporous carbon-silica composite as hard template. Hier-ZSM-5- x exhibits improved mass transport properties, excellent mechanical and hydrothermal stability, and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction. Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores, which increases the final catalytic conversion. The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites. These poisoned Hier-ZSM-5- x shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite, which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant, leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites. This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance.
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高影响因子
VACUUM
·
2021
·
IF 3.627
Lixia Xi,Shuang Guo,Kai Ding,Konda Gokuldoss Prashanth,Baran Sarac,Jürgen Eckert
The coarsening of primary silicon phases is one of the main challenges in the preparation and application of Al-high Si content alloys. In this work, AlSi40 alloys were manufactured by selective laser melting (SLM). The influence of ceramic nanoparticles on the morphology and size of primary Si phase(s) is investigated. With addition of ceramic nanoparticles, large snow-shaped primary Si changes towards a polygonal shape in coarse regions, while blocky primary Si in fine regions shows insignificant change. The size of primary Si in the modified alloy decreases by ~27.1% and ~25.2% in the respective coarse and fine regions compared to that of the unmodified alloy. Due to the refinement and smoothening of primary Si in the modified alloy, the microhardness distribution becomes homogeneous and an average value of ~233 HV 0.2 was obtained. The coefficient of friction (COF) value and the wear rate are ~0.44 and ~4.5 × 10 −5 mm 3 N −1 m −1 , respectively. An ultimate compressive strength of ~0.76 GPa and a maximum compressive strain of ~7.99% are obtained, increasing by ~21.0% and ~18.0% compared to those of the unmodified alloy. The SLM-fabricated AlSi40 alloys upon heat treatment showed an improved plasticity and slightly decreased strength due to the coarsening of primary Si and grains, decreased solid solution of Si in the matrix as well as accommodation of residual stresses after heat treatment.
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Inorganic Chemistry Frontiers
·
2019
·Vol. 6
·期 8
·1996-2003
·
IF 5.934
Xu Cheng,Ren Na,Xiaxia Wang,Nan Xia,Zhongqiang Shan,Jianhua Tian
One of the key technical challenges in the practical application of high-capacity Si-based anode materials in lithium-ion batteries is to enhance the cycling stability of the electrode. In this report, Si nanoparticles incorporated with a 3D carbon hybrid framework composed of S-doped carbon fibers and reduced graphene oxide (Si/SCF@rGO) was synthesized by combining the in situ polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) with chemical reduction and the pyrolysis process. The Si nanoparticles were well dispersed in the 3D carbon hybrid framework, which was further confirmed by SEM, TEM, and XRD. Owing to its well-constructed structure, which is favorable for fast charge transfer, the Si/SCF@rGO composite was tested as an anode in a lithium-ion battery. When cycled at 400 mA g−1, a reversible capacity of 1441.0 mA h g−1 could be retained after 100 cycles. Even when the current density increased to 3.2 A g−1, the reversible capacity could reach 572.1 mA h g−1. The enhanced cycling performance can be ascribed to the hierarchical structure of the carbon framework. The SCF in the carbon hybrid framework improves the dispersion and enhances the electron transfer between the Si nanoparticles. Also, the void surrounding the Si nanoparticles constructed by rGO could effectively accommodate the volume expansion and provide an extra protective layer for the active material to prevent the direct contact with the electrolyte, thus contributing to a comparably stable electrode structure.
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ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Lunlun Gong,Heng Yin,Chengming Nie,Xuran Sun,Xiuli Wang,Mei Wang
Although hybrid photocathodes built by immobilizing molecular catalysts to the surface of semiconductors through chemical linkages have been reported in recent years, systematic and comparative studies remain scarce about the impact of various anchoring groups on the performance, stability, and charge-transfer kinetics of molecular catalyst-decorated hybrid photocathodes for photoelectrochemical (PEC) H2 production. In this study, the molecular cobaloxime catalysts, CoPy-4-X (Py = pyridine, X = PO3H2, COOH, and CONH(OH)), bearing different anchoring groups were synthesized and covalently immobilized to the surface of the porous TiO2 layer coated on a p-Si plate or a fluorine-doped tin oxide glass. The influence of the anchoring groups on the performance of p-Si/TiO2/CoPy-4-X photocathodes was comparatively studied for PEC H2 evolution. Among the tested hybrid photocathodes, the one with a hydroxamate as an anchoring group displayed higher activity and lower charge-transfer resistance than that observed for the electrode with a carboxylate or a phosphonate as the anchoring group. Notably, the catalytic current of p-Si/TiO2/CoPy-4-CONH(OH) was attenuated only by 2.9% in the controlled potential photoelectrolysis tests in borate buffer solution at pH 9 at 0 V versus a reversible hydrogen electrode over 6 h. Moreover, the influence of anchoring groups on the interfacial electron transfer from the TiO2 layer to the immobilized cobaloxime catalyst and electron–hole recombination was studied by transient absorption spectroscopy. These results revealed that the hydroxamate as an anchoring group is superior to the carboxylate and phosphonate groups for speeding up the interfacial electron transfer and firmly immobilizing the molecular catalysts to the metal oxide semiconductors to build efficient and stable hybrid photoelectrodes.
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