Silicone rubber(SR)is a versatile material widely used across various advanced functional applications,such as soft actuators and robots,flexible electronics,and medical devices.However,most SR molding methods rely on...Silicone rubber(SR)is a versatile material widely used across various advanced functional applications,such as soft actuators and robots,flexible electronics,and medical devices.However,most SR molding methods rely on traditional thermal processing or direct ink writing three-dimensional(3D)printing.These methods are not conducive to manufacturing complex structures and present challenges such as time inefficiency,poor accuracy,and the necessity of multiple steps,significantly limiting SR applications.In this study,we developed an SR-based ink suitable for vat photopolymerization 3D printing using a multi-thiol monomer.This ink enables the one-step fabrication of complex architectures with high printing resolution at the micrometer scale,providing excellent mechanical strength and superior chemical stability.Specifically,the optimized 3D printing SR-20 exhibits a tensile stress of 1.96 MPa,an elongation at break of 487.9%,and an elastic modulus of 225.4 kPa.Additionally,the 3D-printed SR samples can withstand various solvents(acetone,toluene,and tetrahydrofuran)and endure temperatures ranging from-50℃ to 180℃,demonstrating superior stability.As a emonstration of the application,we successfully fabricated a series of SR-based soft pneumatic actuators and grippers in a single step with this technology,allowing for free assembly for the first time.This ultraviolet-curable SR,with high printing resolution and exceptional stability performance,has significant potential to enhance the capabilities of 3D printing for applications in soft actuators,robotics,flexible electronics,and medical devices.展开更多
Silicon(Si)is considered one of the most promising anode materials for next-generation lithium-ion batteries due to its ultrahigh theoretical capacity.However,its application is significantly limited by severe volume ...Silicon(Si)is considered one of the most promising anode materials for next-generation lithium-ion batteries due to its ultrahigh theoretical capacity.However,its application is significantly limited by severe volume expansion,leading to structural degradation and poor cycling stability.Polymer binders play a critical role in addressing these issues by providing mechanical stabilization.Inspired by the mechanically adaptive architecture of spider webs,where stiff radial threads and extensible spiral threads act in synergy,a dual-thread architecture polymer binder(PALT)with energy dissipation ability enabled by integrating rigid and flexible domains is designed.The rigid poly(acrylic acid lithium)(PAALi)segments offer structural reinforcement,while the soft segments(poly(lipoic acid-tannic acid),LT)introduce dynamic covalent bonds and multiple hydrogen bonds that function as reversible sacrificial bonds,enhancing energy dissipation during cycling.Comprehensive experimental and computational analyses demonstrate effectively reduced stress concentration,improved structural integrity,and stable electrochemical performance over prolonged cycling.The silicon anode incorporating the PALT binder exhibits a satisfying capacity loss per cycle of 0.042% during 350 charge/discharge cycles at 3580 m A g^(-1).This work highlights a bioinspired binder design strategy that combines intrinsic rigidity with dynamic stress adaptability to advance the mechanical and electrochemical stability of silicon anodes.展开更多
Polyacrylic acid(PAA)-based binders have been demonstrated to significantly enhance the cycling stability of pure silicon(Si)anodes compared to other binder types.However,there is a notable lack of systematic and in-d...Polyacrylic acid(PAA)-based binders have been demonstrated to significantly enhance the cycling stability of pure silicon(Si)anodes compared to other binder types.However,there is a notable lack of systematic and in-depth investigation into the relationship between the molecular weight(MW)of PAA and its performance in pure Si anodes,leading to an absence of reliable theoretical guidance for designing and optimizing of PAA-based binders for these anodes.Herein,we select a series of PAA with varying MWs as binders for Si nanoparticle(SiNP)anodes to systematically identify the optimal MW of PAA for enhancing the electrochemical performance of SiNP anodes.The actual MWs of the various PAA were confirmed by gel permeation chromatography to accurately establish the relationship between MW and binder performance.Within an ultrawide weight average molecular weight(M_(w))range of 35.9-4850 kDa,we identify that the PAA binder with a M_(w)of 1250 kDa(PAA125)exhibits the strongest mechanical strength and the highest adhesion strength,attributed to its favorable molecular chain orientation and robust interchain interactions.These characteristics enable the SiNP anodes utilizing PAA125 to maintain the best interfacial chemistry and bulk mechanical structure stability,leading to optimal electrochemical performance.Notably,the enhancement in cycling stability of SiNP anode by PAA125 under practical application conditions is further validated by the 1.1 Ah LLNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/SiNP@PAA125 pouch cell.展开更多
Severe structural fractures and persistent side reactions at the interface with liquid electrolytes have hindered the commercialization of silicon(Si)anodes.Solid-state electrolytes present a promising solution to add...Severe structural fractures and persistent side reactions at the interface with liquid electrolytes have hindered the commercialization of silicon(Si)anodes.Solid-state electrolytes present a promising solution to address these issues.However,the high interfacial resistance of rigid ceramic electrolytes and the limited ionic conductivity of polymer electrolytes remain significant challenges,further complicated by the substantial volume expansion of Si.In this work,we chemically grafted a flame-retardant,self-healing polyurethane-thiourea polymer onto Li_(7)P_(3)S_(11)(SHPUSB-40%LPS)via nucleophilic addition,creating an electrolyte with exceptional ionic conductivity,high elasticity,and strong compatibility with Si anodes.We observed that FSI^(-)was strongly adsorbed onto the LPS surface through electrostatic interactions with sulfur vacancies,enhancing Li^(+)transport.Furthermore,SHPUSB-40%LPS exhibits dynamic covalent disulfide bonds and hydrogen bonds,enabling self-assembly of the electrolyte at the interface.This dynamic bonding provides a self-healing mechanism that mitigates structural changes during Si expansion and contraction cycles.As a result,the Si anode with SHPUSB-40%LPS presents excellent cycling stability,retaining nearly 53.5%of its capacity after 300 cycles.The practical applicability of this design was validated in a 2 Ah all-solid-state Si‖LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)pouch cell,which maintained a stable Li-ion storage capacity retention of 76.3%after 350cycles at 0.5C.This novel solid-state electrolyte with selfhealing properties offers a promising strategy to address fundamental interfacial and performance challenges associated with Si anodes.展开更多
Nowadays,a stack of heavily doped polysilicon(poly-Si)and tunnel oxide(SiO_(x))is widely employed to improve the passivation performance in n-type tunnel oxide passivated contact(TOPCon)silicon solar cells.In this cas...Nowadays,a stack of heavily doped polysilicon(poly-Si)and tunnel oxide(SiO_(x))is widely employed to improve the passivation performance in n-type tunnel oxide passivated contact(TOPCon)silicon solar cells.In this case,it is critical to develop an in-line advanced fabrication process capable of producing high-quality tunnel SiO_(x).Herein,an in-line ozone-gas oxidation(OGO)process to prepare the tunnel SiO_(x) is proposed to be applied in n-type TOPCon solar cell fabrication,which has obtained better performance compared with previously reported in-line plasma-assisted N2O oxidation(PANO)process.In order to explore the underlying mechanism,the electrical properties of the OGO and PANO tunnel SiO_(x) are analyzed by deep-level transient spectroscopy technology.Notably,continuous interface states in the band gap are detected for OGO tunnel SiO_(x),with the interface state densities(D_(it))of 1.2×10^(12)–3.6×10^(12) cm^(-2) eV^(-1) distributed in Ev+(0.15–0.40)eV,which is significantly lower than PANO tunnel SiO_(x).Furthermore,X-ray photoelectron spectroscopy analysis indicate that the percentage of SiO_(2)(Si^(4+))in OGO tunnel SiO_(x) is higher than which in PANO tunnel SiO_(x).Therefore,we ascribe the lower D_(it) to the good inhibitory effects on the formation of low-valent silicon oxides during the OGO process.In a nutshell,OGO tunnel SiO_(x) has a great potential to be applied in n-type TOPCon silicon solar cell,which may be available for global photovoltaics industry.展开更多
The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbi...The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbide nanowires using lignite and waste silicon powder as raw materials through carbothermal reduction.The staggered structure of nanowires promotes the creation of interfacial polarization,impedance matching,and multiple loss mechanisms,leading to enhanced electromagnetic absorption performance.The silicon carbide nanowires demonstrate outstanding electromagnetic absorption capabilities with the minimum reflection loss of-48.09 d B at10.08 GHz and an effective absorption bandwidth(the reflection loss less than-10 d B)ranging from 8.54 to 16.68 GHz with a thickness of 2.17 mm.This research presents an innovative approach for utilizing solid waste in an environmentally friendly manner to produce broadband silicon carbide composite absorbers.展开更多
To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.T...To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.展开更多
By using LPCVD SiO 2 and poly silicon as sacrificial layer and cantilever respectively,a poly silicon micromachined RF MEMS(radio frequency microelectronic mechanical system) switch is fabricated.During the fabrica...By using LPCVD SiO 2 and poly silicon as sacrificial layer and cantilever respectively,a poly silicon micromachined RF MEMS(radio frequency microelectronic mechanical system) switch is fabricated.During the fabrication process,the stress of poly silicon is released to prevent poly silicon membrane from bending,and the issue of compatibility between RF switch and IC process technology is also resolved.The low residual tensile stress poly silicon cantilever is obtained by the optimization.The switch is tested,and the preliminary test results show:the pull down voltage is 89V,and the switch speed is about 5μs.The switch provides the potential to build a new fully monolithic integrated RF MEMS for radar and communications applications.展开更多
We present an improved angle polishing method in which the end of the cover slice near the glue layer is beveled into a thin,defect-free wedge,the straight edge of which is used as the datum for measuring the depth of...We present an improved angle polishing method in which the end of the cover slice near the glue layer is beveled into a thin,defect-free wedge,the straight edge of which is used as the datum for measuring the depth of subsurface damage. The bevel angle can be calculated from the interference fringes formed in the wedge. The minimum depth of the subsurface damage that can be measured by this method is a few hundred nanometers. Our results show that the method is straightforward, accurate, and convenient.展开更多
β-SiC ceramic powders were obtained by pyrolyzing polycarbosilane in vacuum at 800-1200 °C. The β-SiC ceramic powders were characterized by TGA/DSC, XRD and Raman spectroscopy. The dielectric properties of β-S...β-SiC ceramic powders were obtained by pyrolyzing polycarbosilane in vacuum at 800-1200 °C. The β-SiC ceramic powders were characterized by TGA/DSC, XRD and Raman spectroscopy. The dielectric properties of β-SiC ceramic powders were investigated by measuring their complex permittivity by rectangle wave guide method in the frequency range of 8.2-18 GHz. The results show that both real part ε′ and imaginary part ε″ of complex permittivity increase with increasing pyrolysis temperature. The mechanism was proposed that order carbon formed at high temperature resulted in electron relaxation polarization and conductance loss, which contributes to the increase in complex permittivity.展开更多
Oxygen and carbon behaviors and minority-carrier lifetimes in multi-crystalline silicon （mc-Si） used for solar cells are investigated by FTIR and QSSPCD before and after annealing at 750～ 1150℃ in N2 and O2 ambien...Oxygen and carbon behaviors and minority-carrier lifetimes in multi-crystalline silicon （mc-Si） used for solar cells are investigated by FTIR and QSSPCD before and after annealing at 750～ 1150℃ in N2 and O2 ambient. For comparison, the annealing of CZ silicon with nearly the same oxygen and carbon concentrations is also carried out under the same conditions. The results reveal that the oxygen and carbon concentrations of mc-Si and CZ-Si have a lesser decrease,which means oxygen precipitates are not generated,and grain boundaries in mc-Si do not affect carbon behavior. Bulk lifetime of mc-Si increases in N2 and O2 ambient at 850,950,and 1150℃ ,and the lifetime of mc-Si wafers annealed in 02 are higher than those annealed in N2, which shows that a lot of impurities in mc-Si at high temperature annealing diffuse to grain boundaries,greatly reducing recombination centers. Interstitial Si atoms filling vacancies or recombination centers increases lifetime.展开更多
Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si...Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.展开更多
As an essential elastomer used in edge technologies, fluorosilicone rubber(FSR) suffers serious oxidative ageing problem when serving at high temperature. Cerium oxide is generally used as an antioxidant additive but ...As an essential elastomer used in edge technologies, fluorosilicone rubber(FSR) suffers serious oxidative ageing problem when serving at high temperature. Cerium oxide is generally used as an antioxidant additive but remains unsatisfactory. In order to obtain better antioxidant effect on improving the thermal stability of FSR, a kind of cerium-containing polymethylphenyl silicone(PSI-Ce) was synthesized and the structure was verified by Fourier-transform infrared spectroscopy(FTIR) and proton nuclear magnetic resonance(1HNMR). Due to the homogeneous dispersion on molecular scale, PSI-Ce imposed much better antioxidant effect than the commercial CeO2 did, no matter from isothermal degradation at 320 ℃ or thermal-oxidative ageing test at 230 ℃. In particular, after ageing for 72 h,FSR/PSI-Ce(2 phr) maintained 82% of tensile strength and 63% of elongation at break, in comparison to the corresponding values of 48%and 42% for FSR/CeO2(2 phr). Moreover, 2 phr PSI-Ce was equivalent to 0.046 phr CeO2 according to cerium element conservation.展开更多
The rapid development of photovoltaic （PV） industries has led to a shortage of silicon feedstock. However, more than 40% silicon goes into slurry wastes due to the kerf loss in the wafer slicing process. To effectiv...The rapid development of photovoltaic （PV） industries has led to a shortage of silicon feedstock. However, more than 40% silicon goes into slurry wastes due to the kerf loss in the wafer slicing process. To effectively recycle polycrystalline silicon from the kerf loss slurry, an innovative double-layer organic solvent sedimentation process was presented in the paper. The sedimentation velocities of Si and SiC particles in some organic solvents were investigated. Considering the polarity, viscosity, and density of solvents, the chloroepoxy propane and carbon tetrachloride were selected to separate Si and SiC particles. It is found that Si and SiC particles in the slurry waste can be successfully separated by the double-layer organic solvent sedimentation method, which can greatly reduce the sedimentation time and improve the purity of obtained Si-rich and SiC-rich powders. The obtained Si-rich powders consist of 95.04% Si, and the cast Si ingot has 99.06% Si.展开更多
A thin layer of poly(vinyl alcohol)(PVA) was coated on the surface of silicon carbide whiskers(SCWs)and crosslinked by glutaraldehyde, and then these modified whiskers(mSCWs) were incorporated into high density polyet...A thin layer of poly(vinyl alcohol)(PVA) was coated on the surface of silicon carbide whiskers(SCWs)and crosslinked by glutaraldehyde, and then these modified whiskers(mSCWs) were incorporated into high density polyethylene(HDPE) to prepare HDPE/mSCW composites with a high thermal conductivity.The thermal conductivity, mechanical properties, heat resistance, thermal stability and morphology of HDPE/mSCW and HDPE/SCW composites were characterized and compared. The results reveal that the thermal conductivity of both HDPE/SCW and HDPE/mSCW composites increases with the increase of filler loading, and reaches a maximum of 1.48 and 1.69 W/(m K) at 40 wt% filler loading, which is 251.20% and 300.75% higher than that of HDPE, respectively. Significantly, HDPE/mSCW composites have a higher thermal conductivity than their HDPE/SCW counterparts with the same filler loading. In addition, the heat resistance, Young’s modulus and yield strength of both HDPE/SCW and HDPE/mSCW composites are also improved compared with that of HDPE. mSCW can be homogenously dispersed in the HDPE matrix, which contributes to the formation of thermally conductive networks by the inter-connection of mSCWs.展开更多
Silicon nitride (Si 3N 4) has been the main material for balls in ceramic ball bearings, for its lower density, high strength, high hardness, fine thermal stability and anticorrosive, and is widely used in various fie...Silicon nitride (Si 3N 4) has been the main material for balls in ceramic ball bearings, for its lower density, high strength, high hardness, fine thermal stability and anticorrosive, and is widely used in various fields, such as high speed and high temperature areojet engines, precision machine tools and chemical engineer machines. Silicon nitride ceramics is a kind of brittle and hard material that is difficult to machining. In the traditional finishing process of silicon nitride balls, balls are lapped by expensive diamond abrasive. The machining is inefficiency and the cost is high, but also lots of pits, scratch subsurface micro crazes and dislocations will be caused on the surface of the balls, the performance of the ball bearings would be declined seriously. In these year, a kind of new technology known as chemical mechanical polishing is introduced in the ultraprecision machining process of ceramic balls. In this technology, abrasives such as ZrO 2, CeO 2 whose hardness is close to or lower than the work material (Si 3N 4) are used to polishing the balls. In special slurry, these abrasives can chemo-mechanically react with the work material and environment (air or water) to generate softer material (SiO 2). And the resultants will be removed easily at 0.1 nm level. So the surface defects can be minimized, very smooth surface (Ra=4 nm) and fine sphericity (0.15～0.25 μm ) can be obtained, and the machining efficiency is also improved. The action mechanism of the abrasives in the chemical mechanical polishing process in finishing of silicon nitride ball will be introduced in this paper.展开更多
A novel flame retardant （DAPSiO）, containing silicon and nitrogen, was synthesized by using dichlorodiphenylsilane, γchloropropyl methyl dimethoxysilane and 1,2-ethanediamine. DAPSiO was used together with potassiu...A novel flame retardant （DAPSiO）, containing silicon and nitrogen, was synthesized by using dichlorodiphenylsilane, γchloropropyl methyl dimethoxysilane and 1,2-ethanediamine. DAPSiO was used together with potassium-4-（phenylsulfonyl）benzenesulfonate （KSS） to prepare a flame-retardant system for polycarbonate （PC）. The structure of DAPSiO was characterized by Fourier transform infrared spectroscopy （FTIR）, and 1H-NMR tests. Flammability and thermal behaviors of PC/KSS/DAPSiO systems were estimated by limited oxygen index （LOI）, vertical burning test （UL-94） and thermogravimetric analysis （TGA） tests. The results showed that the flame retardancy and thermal stability of PC/KSS system were improved with the addition of DAPSiO. When 1 wt% DAPSiO and 0.5 wt% KSS were incorporated, the LOI value of PC was found to be 44, and class V-0 of UL-94 test was passed. The scanning electron microscopy （SEM） and FTIR indicated that PC/KSS/DAPSiO system held a more cohesive and denser char structure when compared with pure PC and PC/KSS system.展开更多
The hydrophilicity of silicone hydrogels used as soft corneal contact lens plays an important role in wearing comfort. In order to enhance hydrophilicity and protein resistance, silicone hydrogel membranes were modifi...The hydrophilicity of silicone hydrogels used as soft corneal contact lens plays an important role in wearing comfort. In order to enhance hydrophilicity and protein resistance, silicone hydrogel membranes were modified by atmospheric pressure glow discharge plasma （APGDP） induced surface graft polymerization of N-vinyl pyrrolidone （NVP） and poly（oligoethylene glycol methyl ether methacrylate） （PEGMA） in this paper. XPS analysis demonstrated the success of graft polymerization of NVP and PEGMA onto the surface of silicone hydrogel membranes. The hydrophilicity of silicone hydrogels was characterized by the measurement of water contact angle （WCA）. The result showed that NVP grafted silicone hydrogel has the WCA of about 68° and PEGMA grafted silicone hydrogel has the lowest WCA of about 62°, while the pristine silicone hydrogel is hydrophobic with the WCA of about 103°. Protein resistance of silicone hydrogels was investigated by the method of bicinchoninic acid assay using bovine serum albumin （BSA） as a model. It＇s found that the grafted silicone hydrogel has a significant improvement of protein resistance, and PEGMA grafting is more efficient for the reduction of protein adsorption than NVP grafting. The silicone hydrogel membranes grafted with NVP and PEGMA are good candidates of soft corneal contact lenses.展开更多
Mesoporous silicon carbide with high specific surface area was successfully synthesized from an MCM-48/ polyacrylamide nanocomposite precursor in the temperature range of 550-600 ℃ （below the melting point of Mg） b...Mesoporous silicon carbide with high specific surface area was successfully synthesized from an MCM-48/ polyacrylamide nanocomposite precursor in the temperature range of 550-600 ℃ （below the melting point of Mg） by means of a magnesiothermic reduction process. The MCM-48/polyacrylamide precursor nanocomposite was prepared by in-situ polymerization of acrylamide monomer in the presence of mesoporous MCM-48 synthesized by sol-gel method. The physicochemical properties and microstructures of the nanocomposite precursor and the low-temperature SiC product were characterized by X-ray diffraction （XRD）, differential scanning calorimetry-thermo gravimetric analysis （DSC-TGA）, transmission electron microscopy （TEM） and N2 adsorption-desorption. TEM micrographs and Brunauer-Emmett-Teller （BET） gas adsorption studies showed that the SiC powder was nanocrystalline and had a specific surface area of 330 m2/g and a mesoporosity in the range of 2-10 nm. The presence of an exothermic peak in the DSC trace corresponds to the self-combustion process of the SiC magnesiothermic synthesis. The results also show that the carbon in excess to that required to produce SiC plays a role in the reduction of the SiO2. The mechanism of magnesiothermic synthesis of mesoporous SiC is discussed.展开更多
基金supported by the Strategic Priority Program of the Chinese Academy of Sciences(XDB0470303)the National Key R&D Program of China(2022YFB4600102and 2023YFE0209900)+4 种基金the National Natural Science Foundation of China(52175201 and 51935012)the science and technology projects of Gansu province(22JR5RA093,24JRRA044,24YFFA014 and 24ZDGA014)the Innovation and Entrepreneurship Team Project of YEDA(2021TD007)the special supporting project for provincial leading talents of Yantaithe Taishan Scholars Program。
文摘Silicone rubber(SR)is a versatile material widely used across various advanced functional applications,such as soft actuators and robots,flexible electronics,and medical devices.However,most SR molding methods rely on traditional thermal processing or direct ink writing three-dimensional(3D)printing.These methods are not conducive to manufacturing complex structures and present challenges such as time inefficiency,poor accuracy,and the necessity of multiple steps,significantly limiting SR applications.In this study,we developed an SR-based ink suitable for vat photopolymerization 3D printing using a multi-thiol monomer.This ink enables the one-step fabrication of complex architectures with high printing resolution at the micrometer scale,providing excellent mechanical strength and superior chemical stability.Specifically,the optimized 3D printing SR-20 exhibits a tensile stress of 1.96 MPa,an elongation at break of 487.9%,and an elastic modulus of 225.4 kPa.Additionally,the 3D-printed SR samples can withstand various solvents(acetone,toluene,and tetrahydrofuran)and endure temperatures ranging from-50℃ to 180℃,demonstrating superior stability.As a emonstration of the application,we successfully fabricated a series of SR-based soft pneumatic actuators and grippers in a single step with this technology,allowing for free assembly for the first time.This ultraviolet-curable SR,with high printing resolution and exceptional stability performance,has significant potential to enhance the capabilities of 3D printing for applications in soft actuators,robotics,flexible electronics,and medical devices.
基金the National Natural Science Foundation of China(32201497)for the financial support of this research。
文摘Silicon(Si)is considered one of the most promising anode materials for next-generation lithium-ion batteries due to its ultrahigh theoretical capacity.However,its application is significantly limited by severe volume expansion,leading to structural degradation and poor cycling stability.Polymer binders play a critical role in addressing these issues by providing mechanical stabilization.Inspired by the mechanically adaptive architecture of spider webs,where stiff radial threads and extensible spiral threads act in synergy,a dual-thread architecture polymer binder(PALT)with energy dissipation ability enabled by integrating rigid and flexible domains is designed.The rigid poly(acrylic acid lithium)(PAALi)segments offer structural reinforcement,while the soft segments(poly(lipoic acid-tannic acid),LT)introduce dynamic covalent bonds and multiple hydrogen bonds that function as reversible sacrificial bonds,enhancing energy dissipation during cycling.Comprehensive experimental and computational analyses demonstrate effectively reduced stress concentration,improved structural integrity,and stable electrochemical performance over prolonged cycling.The silicon anode incorporating the PALT binder exhibits a satisfying capacity loss per cycle of 0.042% during 350 charge/discharge cycles at 3580 m A g^(-1).This work highlights a bioinspired binder design strategy that combines intrinsic rigidity with dynamic stress adaptability to advance the mechanical and electrochemical stability of silicon anodes.
基金funding supports of the National Natural Science Foundation of China(52402315,52172244,51874104,and 52172190)the"Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang"(2023R01007)the Zhejiang Provincial"Jianbing"and"Lingyan"R&D Programs(Grant No.2024C01262)。
文摘Polyacrylic acid(PAA)-based binders have been demonstrated to significantly enhance the cycling stability of pure silicon(Si)anodes compared to other binder types.However,there is a notable lack of systematic and in-depth investigation into the relationship between the molecular weight(MW)of PAA and its performance in pure Si anodes,leading to an absence of reliable theoretical guidance for designing and optimizing of PAA-based binders for these anodes.Herein,we select a series of PAA with varying MWs as binders for Si nanoparticle(SiNP)anodes to systematically identify the optimal MW of PAA for enhancing the electrochemical performance of SiNP anodes.The actual MWs of the various PAA were confirmed by gel permeation chromatography to accurately establish the relationship between MW and binder performance.Within an ultrawide weight average molecular weight(M_(w))range of 35.9-4850 kDa,we identify that the PAA binder with a M_(w)of 1250 kDa(PAA125)exhibits the strongest mechanical strength and the highest adhesion strength,attributed to its favorable molecular chain orientation and robust interchain interactions.These characteristics enable the SiNP anodes utilizing PAA125 to maintain the best interfacial chemistry and bulk mechanical structure stability,leading to optimal electrochemical performance.Notably,the enhancement in cycling stability of SiNP anode by PAA125 under practical application conditions is further validated by the 1.1 Ah LLNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/SiNP@PAA125 pouch cell.
基金supported financially by the National Natural Science Foundation of China(No.52172202)Science and Technology Program of Guangzhou,China(No.SL2024A03J00326)+1 种基金Key Research and Development project of High-Level Scientific and Technological Talent Introduction for Luliang City(No.2023RC27)the Basic Research Program(Free Exploration Category)Project for Shanxi Province(No.202303021222251)
文摘Severe structural fractures and persistent side reactions at the interface with liquid electrolytes have hindered the commercialization of silicon(Si)anodes.Solid-state electrolytes present a promising solution to address these issues.However,the high interfacial resistance of rigid ceramic electrolytes and the limited ionic conductivity of polymer electrolytes remain significant challenges,further complicated by the substantial volume expansion of Si.In this work,we chemically grafted a flame-retardant,self-healing polyurethane-thiourea polymer onto Li_(7)P_(3)S_(11)(SHPUSB-40%LPS)via nucleophilic addition,creating an electrolyte with exceptional ionic conductivity,high elasticity,and strong compatibility with Si anodes.We observed that FSI^(-)was strongly adsorbed onto the LPS surface through electrostatic interactions with sulfur vacancies,enhancing Li^(+)transport.Furthermore,SHPUSB-40%LPS exhibits dynamic covalent disulfide bonds and hydrogen bonds,enabling self-assembly of the electrolyte at the interface.This dynamic bonding provides a self-healing mechanism that mitigates structural changes during Si expansion and contraction cycles.As a result,the Si anode with SHPUSB-40%LPS presents excellent cycling stability,retaining nearly 53.5%of its capacity after 300 cycles.The practical applicability of this design was validated in a 2 Ah all-solid-state Si‖LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)pouch cell,which maintained a stable Li-ion storage capacity retention of 76.3%after 350cycles at 0.5C.This novel solid-state electrolyte with selfhealing properties offers a promising strategy to address fundamental interfacial and performance challenges associated with Si anodes.
基金supported by the National Natural Science Foundation of China(Nos.62025403 and U23A20354)the Natural Science Foundation of Zhejiang Province(LD22E020001)+1 种基金“Pioneer”and“Leading Goose”R&D Program of Zhejiang(2022C01215,2024C01055)the Fundamental Research Funds for the Central Universities(226-2022-00200).
文摘Nowadays,a stack of heavily doped polysilicon(poly-Si)and tunnel oxide(SiO_(x))is widely employed to improve the passivation performance in n-type tunnel oxide passivated contact(TOPCon)silicon solar cells.In this case,it is critical to develop an in-line advanced fabrication process capable of producing high-quality tunnel SiO_(x).Herein,an in-line ozone-gas oxidation(OGO)process to prepare the tunnel SiO_(x) is proposed to be applied in n-type TOPCon solar cell fabrication,which has obtained better performance compared with previously reported in-line plasma-assisted N2O oxidation(PANO)process.In order to explore the underlying mechanism,the electrical properties of the OGO and PANO tunnel SiO_(x) are analyzed by deep-level transient spectroscopy technology.Notably,continuous interface states in the band gap are detected for OGO tunnel SiO_(x),with the interface state densities(D_(it))of 1.2×10^(12)–3.6×10^(12) cm^(-2) eV^(-1) distributed in Ev+(0.15–0.40)eV,which is significantly lower than PANO tunnel SiO_(x).Furthermore,X-ray photoelectron spectroscopy analysis indicate that the percentage of SiO_(2)(Si^(4+))in OGO tunnel SiO_(x) is higher than which in PANO tunnel SiO_(x).Therefore,we ascribe the lower D_(it) to the good inhibitory effects on the formation of low-valent silicon oxides during the OGO process.In a nutshell,OGO tunnel SiO_(x) has a great potential to be applied in n-type TOPCon silicon solar cell,which may be available for global photovoltaics industry.
基金supported by the National Natural Science Foundation of China(No.52436008)the Inner Mongolia Science and Technology Projects,China(Nos.JMRHZX20210003 and 2023YFCY0009)+3 种基金the Huaneng Group Co Ltd.,China(No.HNKJ23-H50)the National Natural Science Foundation of China(No.22408044)the China Postdoctoral Science Foundation(No.2024M761877)the National Key R&D Program of China(No.SQ2024YFD2200039)。
文摘The electromagnetic wave absorption of silicon carbide nanowires is improved by their uniform and diverse cross-structures.This study introduces a sustainable and high value-added method for synthesizing silicon carbide nanowires using lignite and waste silicon powder as raw materials through carbothermal reduction.The staggered structure of nanowires promotes the creation of interfacial polarization,impedance matching,and multiple loss mechanisms,leading to enhanced electromagnetic absorption performance.The silicon carbide nanowires demonstrate outstanding electromagnetic absorption capabilities with the minimum reflection loss of-48.09 d B at10.08 GHz and an effective absorption bandwidth(the reflection loss less than-10 d B)ranging from 8.54 to 16.68 GHz with a thickness of 2.17 mm.This research presents an innovative approach for utilizing solid waste in an environmentally friendly manner to produce broadband silicon carbide composite absorbers.
基金supported by the Quantum Science and Technology-National Science and Technology Major Project (Grant No.2024ZD0302502 for WZ)the National Natural Science Foundation of China(Grant No.92365210 for WZ)+1 种基金Tsinghua Initiative Scientific Research Program (for WZ)the project of Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies (JIAOT,for YH)。
文摘To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.
文摘By using LPCVD SiO 2 and poly silicon as sacrificial layer and cantilever respectively,a poly silicon micromachined RF MEMS(radio frequency microelectronic mechanical system) switch is fabricated.During the fabrication process,the stress of poly silicon is released to prevent poly silicon membrane from bending,and the issue of compatibility between RF switch and IC process technology is also resolved.The low residual tensile stress poly silicon cantilever is obtained by the optimization.The switch is tested,and the preliminary test results show:the pull down voltage is 89V,and the switch speed is about 5μs.The switch provides the potential to build a new fully monolithic integrated RF MEMS for radar and communications applications.
文摘We present an improved angle polishing method in which the end of the cover slice near the glue layer is beveled into a thin,defect-free wedge,the straight edge of which is used as the datum for measuring the depth of subsurface damage. The bevel angle can be calculated from the interference fringes formed in the wedge. The minimum depth of the subsurface damage that can be measured by this method is a few hundred nanometers. Our results show that the method is straightforward, accurate, and convenient.
基金Project (50572090) supported by the National Natural Science Foundation of ChinaProject (KP200901) supported by the Fund of the State Key Laboratory of Solidification Processing, China
文摘β-SiC ceramic powders were obtained by pyrolyzing polycarbosilane in vacuum at 800-1200 °C. The β-SiC ceramic powders were characterized by TGA/DSC, XRD and Raman spectroscopy. The dielectric properties of β-SiC ceramic powders were investigated by measuring their complex permittivity by rectangle wave guide method in the frequency range of 8.2-18 GHz. The results show that both real part ε′ and imaginary part ε″ of complex permittivity increase with increasing pyrolysis temperature. The mechanism was proposed that order carbon formed at high temperature resulted in electron relaxation polarization and conductance loss, which contributes to the increase in complex permittivity.
文摘Oxygen and carbon behaviors and minority-carrier lifetimes in multi-crystalline silicon （mc-Si） used for solar cells are investigated by FTIR and QSSPCD before and after annealing at 750～ 1150℃ in N2 and O2 ambient. For comparison, the annealing of CZ silicon with nearly the same oxygen and carbon concentrations is also carried out under the same conditions. The results reveal that the oxygen and carbon concentrations of mc-Si and CZ-Si have a lesser decrease,which means oxygen precipitates are not generated,and grain boundaries in mc-Si do not affect carbon behavior. Bulk lifetime of mc-Si increases in N2 and O2 ambient at 850,950,and 1150℃ ,and the lifetime of mc-Si wafers annealed in 02 are higher than those annealed in N2, which shows that a lot of impurities in mc-Si at high temperature annealing diffuse to grain boundaries,greatly reducing recombination centers. Interstitial Si atoms filling vacancies or recombination centers increases lifetime.
文摘Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.
基金financially supported by the National Natural Science Foundation of China (Nos. 51573043 and 21805086)the Fundamental Research Funds for the Central Universities (Nos. 222201817001 and 222201814004)+2 种基金supported by the Shanghai Leading Academic Discipline Project (No. B502)the Shanghai Key Laboratory Project (No. ZD20170203)Support from FSIR Advanced Material Co., Ltd.
文摘As an essential elastomer used in edge technologies, fluorosilicone rubber(FSR) suffers serious oxidative ageing problem when serving at high temperature. Cerium oxide is generally used as an antioxidant additive but remains unsatisfactory. In order to obtain better antioxidant effect on improving the thermal stability of FSR, a kind of cerium-containing polymethylphenyl silicone(PSI-Ce) was synthesized and the structure was verified by Fourier-transform infrared spectroscopy(FTIR) and proton nuclear magnetic resonance(1HNMR). Due to the homogeneous dispersion on molecular scale, PSI-Ce imposed much better antioxidant effect than the commercial CeO2 did, no matter from isothermal degradation at 320 ℃ or thermal-oxidative ageing test at 230 ℃. In particular, after ageing for 72 h,FSR/PSI-Ce(2 phr) maintained 82% of tensile strength and 63% of elongation at break, in comparison to the corresponding values of 48%and 42% for FSR/CeO2(2 phr). Moreover, 2 phr PSI-Ce was equivalent to 0.046 phr CeO2 according to cerium element conservation.
基金financially supported by the National Natural Science Foundation of China(No.51074043)the National Key Technology R&D Program(No.2011BAE03B00)the Fundamental Research Funds for the Central Universities(No.N120409004)
文摘The rapid development of photovoltaic （PV） industries has led to a shortage of silicon feedstock. However, more than 40% silicon goes into slurry wastes due to the kerf loss in the wafer slicing process. To effectively recycle polycrystalline silicon from the kerf loss slurry, an innovative double-layer organic solvent sedimentation process was presented in the paper. The sedimentation velocities of Si and SiC particles in some organic solvents were investigated. Considering the polarity, viscosity, and density of solvents, the chloroepoxy propane and carbon tetrachloride were selected to separate Si and SiC particles. It is found that Si and SiC particles in the slurry waste can be successfully separated by the double-layer organic solvent sedimentation method, which can greatly reduce the sedimentation time and improve the purity of obtained Si-rich and SiC-rich powders. The obtained Si-rich powders consist of 95.04% Si, and the cast Si ingot has 99.06% Si.
基金financially sponsored by the National Natural Science Foundation of China(No.U1507123)the Foundation of Qinghai Science and Technology Department(No.2017-HZ-803)+1 种基金the Thousand Talents Program of Qinghai ProvinceKunlun Scholar Award Program of Qinghai Province
文摘A thin layer of poly(vinyl alcohol)(PVA) was coated on the surface of silicon carbide whiskers(SCWs)and crosslinked by glutaraldehyde, and then these modified whiskers(mSCWs) were incorporated into high density polyethylene(HDPE) to prepare HDPE/mSCW composites with a high thermal conductivity.The thermal conductivity, mechanical properties, heat resistance, thermal stability and morphology of HDPE/mSCW and HDPE/SCW composites were characterized and compared. The results reveal that the thermal conductivity of both HDPE/SCW and HDPE/mSCW composites increases with the increase of filler loading, and reaches a maximum of 1.48 and 1.69 W/(m K) at 40 wt% filler loading, which is 251.20% and 300.75% higher than that of HDPE, respectively. Significantly, HDPE/mSCW composites have a higher thermal conductivity than their HDPE/SCW counterparts with the same filler loading. In addition, the heat resistance, Young’s modulus and yield strength of both HDPE/SCW and HDPE/mSCW composites are also improved compared with that of HDPE. mSCW can be homogenously dispersed in the HDPE matrix, which contributes to the formation of thermally conductive networks by the inter-connection of mSCWs.
文摘Silicon nitride (Si 3N 4) has been the main material for balls in ceramic ball bearings, for its lower density, high strength, high hardness, fine thermal stability and anticorrosive, and is widely used in various fields, such as high speed and high temperature areojet engines, precision machine tools and chemical engineer machines. Silicon nitride ceramics is a kind of brittle and hard material that is difficult to machining. In the traditional finishing process of silicon nitride balls, balls are lapped by expensive diamond abrasive. The machining is inefficiency and the cost is high, but also lots of pits, scratch subsurface micro crazes and dislocations will be caused on the surface of the balls, the performance of the ball bearings would be declined seriously. In these year, a kind of new technology known as chemical mechanical polishing is introduced in the ultraprecision machining process of ceramic balls. In this technology, abrasives such as ZrO 2, CeO 2 whose hardness is close to or lower than the work material (Si 3N 4) are used to polishing the balls. In special slurry, these abrasives can chemo-mechanically react with the work material and environment (air or water) to generate softer material (SiO 2). And the resultants will be removed easily at 0.1 nm level. So the surface defects can be minimized, very smooth surface (Ra=4 nm) and fine sphericity (0.15～0.25 μm ) can be obtained, and the machining efficiency is also improved. The action mechanism of the abrasives in the chemical mechanical polishing process in finishing of silicon nitride ball will be introduced in this paper.
文摘A novel flame retardant （DAPSiO）, containing silicon and nitrogen, was synthesized by using dichlorodiphenylsilane, γchloropropyl methyl dimethoxysilane and 1,2-ethanediamine. DAPSiO was used together with potassium-4-（phenylsulfonyl）benzenesulfonate （KSS） to prepare a flame-retardant system for polycarbonate （PC）. The structure of DAPSiO was characterized by Fourier transform infrared spectroscopy （FTIR）, and 1H-NMR tests. Flammability and thermal behaviors of PC/KSS/DAPSiO systems were estimated by limited oxygen index （LOI）, vertical burning test （UL-94） and thermogravimetric analysis （TGA） tests. The results showed that the flame retardancy and thermal stability of PC/KSS system were improved with the addition of DAPSiO. When 1 wt% DAPSiO and 0.5 wt% KSS were incorporated, the LOI value of PC was found to be 44, and class V-0 of UL-94 test was passed. The scanning electron microscopy （SEM） and FTIR indicated that PC/KSS/DAPSiO system held a more cohesive and denser char structure when compared with pure PC and PC/KSS system.
基金supported by Hydron Contact Lens Co.,Ltd and National Natural Science Foundation of China (No.50673019)
文摘The hydrophilicity of silicone hydrogels used as soft corneal contact lens plays an important role in wearing comfort. In order to enhance hydrophilicity and protein resistance, silicone hydrogel membranes were modified by atmospheric pressure glow discharge plasma （APGDP） induced surface graft polymerization of N-vinyl pyrrolidone （NVP） and poly（oligoethylene glycol methyl ether methacrylate） （PEGMA） in this paper. XPS analysis demonstrated the success of graft polymerization of NVP and PEGMA onto the surface of silicone hydrogel membranes. The hydrophilicity of silicone hydrogels was characterized by the measurement of water contact angle （WCA）. The result showed that NVP grafted silicone hydrogel has the WCA of about 68° and PEGMA grafted silicone hydrogel has the lowest WCA of about 62°, while the pristine silicone hydrogel is hydrophobic with the WCA of about 103°. Protein resistance of silicone hydrogels was investigated by the method of bicinchoninic acid assay using bovine serum albumin （BSA） as a model. It＇s found that the grafted silicone hydrogel has a significant improvement of protein resistance, and PEGMA grafting is more efficient for the reduction of protein adsorption than NVP grafting. The silicone hydrogel membranes grafted with NVP and PEGMA are good candidates of soft corneal contact lenses.
文摘Mesoporous silicon carbide with high specific surface area was successfully synthesized from an MCM-48/ polyacrylamide nanocomposite precursor in the temperature range of 550-600 ℃ （below the melting point of Mg） by means of a magnesiothermic reduction process. The MCM-48/polyacrylamide precursor nanocomposite was prepared by in-situ polymerization of acrylamide monomer in the presence of mesoporous MCM-48 synthesized by sol-gel method. The physicochemical properties and microstructures of the nanocomposite precursor and the low-temperature SiC product were characterized by X-ray diffraction （XRD）, differential scanning calorimetry-thermo gravimetric analysis （DSC-TGA）, transmission electron microscopy （TEM） and N2 adsorption-desorption. TEM micrographs and Brunauer-Emmett-Teller （BET） gas adsorption studies showed that the SiC powder was nanocrystalline and had a specific surface area of 330 m2/g and a mesoporosity in the range of 2-10 nm. The presence of an exothermic peak in the DSC trace corresponds to the self-combustion process of the SiC magnesiothermic synthesis. The results also show that the carbon in excess to that required to produce SiC plays a role in the reduction of the SiO2. The mechanism of magnesiothermic synthesis of mesoporous SiC is discussed.
