Recent success and application of the percolation theory have highlighted cation-disordered Li-rich oxides as high energy density cathode materials. Generally, this kind of cathode materials suffer from low cycling st...Recent success and application of the percolation theory have highlighted cation-disordered Li-rich oxides as high energy density cathode materials. Generally, this kind of cathode materials suffer from low cycling stability and rate performance. Doped Ti4^＋ ions can improve the long-term cycling stability and rate performance of the Li-rich oxides materials with obvious capacity fading. The electrochemical performance in LixNi2-4x/3Sbx/3O2 can benefit a lot from the nanohighway, which is a kind of nanoscale 0-TM diffusion channels in the transition metal layer and provides low diffusion barrier pathways for the lithium diffusion. In this work, the doping effect of Ti on the structure and electrochemical properties in Li1.15Ni0.47Sb0.38O2 is studied. The Ti-stabilized Li1.15-xNi0.47TixSb0.38O2 （x=0, 0.01, 0.03 and 0.05） have been prepared by a solid-state method and the Li1.03Ni0.47Sb0.38Ti0.03O2 sample exhibits outstanding electrochemical performance with a larger reversible discharge capacity, better rate capability and cyclability. Synchrotron-based XANES, combined with ab initio calculations in the multiple-scattering flame- work, reveals the Ti ions have been doped into the Li-site in the lithium layer and formed a distortion TiO6 octahedron. This TiO6 local configuration in the lithium can keep the stability of nanohighway in the electrochemical pro- cess. In particular, the Lil.03Ni0.47Sb0.38Ti0.03O2 compound can deliver a discharge capacities 132 and 76 mAh/g at 0.2 and 5 C, respectivly. About 86% capacity retention occurs at 1 C rate after 500 cycles. This work suggests capacity fading in the oxide cathode materials can be suppressed to construct and stabilize the nanohighway.展开更多
Ti-doped graphite-like carbon （Ti-GLC） films were synthesized successfully by magnetron sputtering technique. The compositions, microstructures and properties of the Ti-doped GLC films dependent on the parameter of ...Ti-doped graphite-like carbon （Ti-GLC） films were synthesized successfully by magnetron sputtering technique. The compositions, microstructures and properties of the Ti-doped GLC films dependent on the parameter of Ti target current were systemically investigated by Raman spectra, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, atomic force microscopy （AFM）, nanoindentation and ball-on-disk tribometer. With the increase of the Ti target current, the ratio of sp2 bond and the content of Ti as well as the film hardness and compressive internal stress increase, but the high content of the Ti would result in the loose film due to the formation of the squamose structure. Less incorporated Ti reduces the friction of the GLC film in dry-sliding condition, while pure GLC film exhibits the lowest friction coefficient in water-lubricated condition. Ti-GLC film deposited with low Ti target current shows high wear resistance in both dry-sliding and water-lubricated conditions.展开更多
A novel Ti-doped M-site deficient olivine LiFePO4, i.e. Li0.95Fe0.95Ti0.05PO4, was synthesized by a solid-state reaction method. XRD and VTR were used to characterize the as-prepared samples. As a cathode material for...A novel Ti-doped M-site deficient olivine LiFePO4, i.e. Li0.95Fe0.95Ti0.05PO4, was synthesized by a solid-state reaction method. XRD and VTR were used to characterize the as-prepared samples. As a cathode material for lithium-ion batteries, Li0.95Fe0.95Ti0.05PO4 exhibited improved rate capability.展开更多
Ti-doped WO3 films were prepared by the mid-frequency dual-target magnetron sputtering method. The structure and electrochromic properties of the Ti-doped WO3 films were analysed by X-Ray diffraction （XRD）, Raman sp...Ti-doped WO3 films were prepared by the mid-frequency dual-target magnetron sputtering method. The structure and electrochromic properties of the Ti-doped WO3 films were analysed by X-Ray diffraction （XRD）, Raman spectroscopy, spectrophotometer, cyclic chronoam- perometry and atomic force microscopy （AFM）. The results indicate that the erystallinity decrease after the doping of titanium, the channels for ion injection and extraction increase, the responding speed with 5.1% titanium doped becomes faster, and its circle life increases more than four times compared with the undoped WO3 film. In the coloured state, the W-O-W bonds decrease, but the W = O bonds increase. Since the W-O-W bonds break down for Li＋ ions＇ injection and more W = O bonds form, it is more convenient to inject Li＋ ions into the Ti-doped film than undoped film because more W-O-W bonds break down in the coloured state.展开更多
Density functional theory （DFT） calculations are conducted to explore the interaction of H2 with pure and Tidoped WO3 （002） surfaces. Four top adsorption models of H2 on pure and Ti-doped WO3 （002） surfaces are ...Density functional theory （DFT） calculations are conducted to explore the interaction of H2 with pure and Tidoped WO3 （002） surfaces. Four top adsorption models of H2 on pure and Ti-doped WO3 （002） surfaces are investigated respectively, they are adsorption on bridging oxygen Olc, absorption on plane oxygen O2c, absorption on 5-fold W5c （Ti）, and absorption on 6-fold W6c. The most stable and H2 possible adsorption structure in the pure surface is H-end oriented to the surface plane oxygen O2c site, while the favourable adsorption sites for H2 in a Ti-doped surface is not only an O2c site but also a W6c site. The adsorption energy, the Fermi energy level EF, and the electronic population are investigated and the H2-sensing mechanism of a pure-doped WO3 （002） surface is revealed theoretically： the theoretical results are in good accordance with our existing experimental results. By comparing the above three terms, it is found that Ti doping can obviously enhance the adsorption of H2. It can be predicted that the method of Ti-doped into a WO3 thin film is an effective way to improve WO3 sensor sensitivity to H2 gas.展开更多
Ti-Modified (Na0.5K0.5)(TixNb1-x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures,and piezoelectric and dielectric properties of the le...Ti-Modified (Na0.5K0.5)(TixNb1-x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures,and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction re-sults indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and...展开更多
We experimentally compare the output abilities of lightly and heavily doped Ti：Sapphire（Ti：S） amplifiers with diameters as large as 150 mm. Although a lightly doped Ti：S is more favorable to overcome parasitic la...We experimentally compare the output abilities of lightly and heavily doped Ti：Sapphire（Ti：S） amplifiers with diameters as large as 150 mm. Although a lightly doped Ti：S is more favorable to overcome parasitic lasing（PL）and transverse amplified spontaneous emission（TASE）, the self-phase-modulation（SPM） effect becomes more pronounced when a longer crystal is used. Recompression of the amplified, stretched pulses can be seriously affected by the SPM effect. We then propose a temporal multi-pulse pump scheme to suppress PL and TASE in a thin, heavily doped Ti：S crystal. This novel temporal multi-pulse pump technique can find potential applications in 10 PW chirped-pulse amplification laser systems.展开更多
Bimetallic layered double hydroxides(LDHs)have attracted substantial attention as oxygen evolution reaction(OER)catalysts.In this work,we provide a facile route to prepare Ti-doped NiCo-LDH/NF electrocatalysts with M...Bimetallic layered double hydroxides(LDHs)have attracted substantial attention as oxygen evolution reaction(OER)catalysts.In this work,we provide a facile route to prepare Ti-doped NiCo-LDH/NF electrocatalysts with M–O–Ti(M=Ni,Co)covalent bonds via a rapid immersion method for the OER process.The experiments and density functional theory(DFT)calculations elucidate that the doping of Ti(M–O–Ti)not only exfoliates the NiCo-LDH nanosheets into spheres but also causes lattice distortion to produce more oxygen vacancies,which promotes faster exchange of intermediates and improves the electron transfer efficiency.These superior physical characters endow Ti-NiCo-LDH with an excellent overpotential of 319 mV at a current density of 50 mA cm^(-2),which is markedly lower than that of NiCo-LDH(391 mV at 50 mA cm^(-2)).Even at a high current density of 100 mA cm^(-2),NiCo-LDH displays an overpotential of 429 mV,whereas Ti-NiCo-LDH is capable of achieving an overpotential of 353 mV.Moreover,the water electrolyzer based on the Ti-NiCo-LDH bifunctional catalyst requires a low cell voltage of 1.60 V to achieve a current density of 10 mA cm^(-2),and the Ti-NiCo-LDH catalyst has been successfully applied for solar cell-driven water electrolysis and the corresponding voltage is about 1.61 V.This work offers a novel strategy to fabricate high activity NiCo-LDH with rich oxygen vacancies toward the OER process.展开更多
High-power laser systems require thin films with extremely low absorption.Ultra-low-absorption films are often fabricated via ion beam sputtering,which is costly and slow.This study analyzes the impact of doping titan...High-power laser systems require thin films with extremely low absorption.Ultra-low-absorption films are often fabricated via ion beam sputtering,which is costly and slow.This study analyzes the impact of doping titanium and annealing on the absorption characteristics of thin films,focusing on composition and structure.The results indicate that the primary factor influencing absorption is composition.Suppressing the presence of electrons or holes that do not form stable chemical bonds can significantly reduce absorption;for amorphous thin films,the structural influence on absorption is relatively minor.Thus,composition control is crucial for fabricating ultra-low-absorption films,while the deposition method is secondary.Ion beam-assisted electron-beam evaporation,which is relatively seldom used for fabricating low-absorption films,was employed to produce high-reflectivity films.After annealing,the absorption at1064 nm reached 1.70 parts per million.This method offers a cost-effective and rapid approach for fabricating ultra-lowabsorption films.展开更多
High-voltage high-nickel lithium layered oxide cathodes show great application prospects to meet the ever-increasing demand for further improvement of the energy density of rechargeable lithium-ion batteries(LIBs)main...High-voltage high-nickel lithium layered oxide cathodes show great application prospects to meet the ever-increasing demand for further improvement of the energy density of rechargeable lithium-ion batteries(LIBs)mainly due to their high output capacity.However,severe bulk structural degradation and undesired electrode-electrolyte interface reactions seriously endanger the cycle life and safety of the battery.Here,2 mol%Ti atom is used as modified material doping into LiNi_(0.8)Co_(0.2)Mn_(0.2O2)(NCM)to reform LiNi_(0.6)Co_(0.2)Mn_(0.18)Ti_(0.02)O_(2)(NCM-Ti)and address the long-standing inherent problem.At a high cut-off voltage of 4.5 V,NCM-Ti delivers a higher capacity retention ratio(91.8%vs.82.9%)after 150 cycles and a superior rate capacity(118 vs.105 mAh·g^(-1))at the high current density of 10 C than the pristine NCM.The designed high-voltage full battery with graphite as anode and NCM-Ti as cathode also exhibits high energy density(240 Wh·kg^(-1))and excellent electrochemical performance.The superior electrochemical behavior can be attributed to the improved stability of the bulk structure and the electrode-electrolyte interface owing to the strong Ti-O bond and no unpaired electrons.The in-situ X-ray diffraction analysis demonstrates that Ti-doping inhibits the undesired H2-H3 phase transition,minimizing the mechanical degradation.The ex-situ TEM and X-ray photoelectron spectroscopy reveal that Ti-doping suppresses the release of interfacial oxygen,reducing undesired interfacial reactions.This work provides a valuable strategic guideline for the application of high-voltage high-nickel cathodes in LIBs.展开更多
基金Supporting information for this article is available on the WWW under http：//dx.doi.org/10. 1002/cjoc.201700265 or from the author.Acknowledgement This work was partly supported by the Science Fund for Creative Re search Groups of NSF C （No. 11321503）, the National Key Research and Development Program of China （No. 2016YFA0401004）, the National Natural Science Foundation of China （NSFC No. 11275227, U1632103）, and the Youth Innovation Promotion Association CAS （No. 2014927）.
文摘Recent success and application of the percolation theory have highlighted cation-disordered Li-rich oxides as high energy density cathode materials. Generally, this kind of cathode materials suffer from low cycling stability and rate performance. Doped Ti4^＋ ions can improve the long-term cycling stability and rate performance of the Li-rich oxides materials with obvious capacity fading. The electrochemical performance in LixNi2-4x/3Sbx/3O2 can benefit a lot from the nanohighway, which is a kind of nanoscale 0-TM diffusion channels in the transition metal layer and provides low diffusion barrier pathways for the lithium diffusion. In this work, the doping effect of Ti on the structure and electrochemical properties in Li1.15Ni0.47Sb0.38O2 is studied. The Ti-stabilized Li1.15-xNi0.47TixSb0.38O2 （x=0, 0.01, 0.03 and 0.05） have been prepared by a solid-state method and the Li1.03Ni0.47Sb0.38Ti0.03O2 sample exhibits outstanding electrochemical performance with a larger reversible discharge capacity, better rate capability and cyclability. Synchrotron-based XANES, combined with ab initio calculations in the multiple-scattering flame- work, reveals the Ti ions have been doped into the Li-site in the lithium layer and formed a distortion TiO6 octahedron. This TiO6 local configuration in the lithium can keep the stability of nanohighway in the electrochemical pro- cess. In particular, the Lil.03Ni0.47Sb0.38Ti0.03O2 compound can deliver a discharge capacities 132 and 76 mAh/g at 0.2 and 5 C, respectivly. About 86% capacity retention occurs at 1 C rate after 500 cycles. This work suggests capacity fading in the oxide cathode materials can be suppressed to construct and stabilize the nanohighway.
基金Project (50905178) supported by the National Natural Science Foundation of ChinaProject (2011CB706603) supported by the National Basic Research Program of China
文摘Ti-doped graphite-like carbon （Ti-GLC） films were synthesized successfully by magnetron sputtering technique. The compositions, microstructures and properties of the Ti-doped GLC films dependent on the parameter of Ti target current were systemically investigated by Raman spectra, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, atomic force microscopy （AFM）, nanoindentation and ball-on-disk tribometer. With the increase of the Ti target current, the ratio of sp2 bond and the content of Ti as well as the film hardness and compressive internal stress increase, but the high content of the Ti would result in the loose film due to the formation of the squamose structure. Less incorporated Ti reduces the friction of the GLC film in dry-sliding condition, while pure GLC film exhibits the lowest friction coefficient in water-lubricated condition. Ti-GLC film deposited with low Ti target current shows high wear resistance in both dry-sliding and water-lubricated conditions.
文摘A novel Ti-doped M-site deficient olivine LiFePO4, i.e. Li0.95Fe0.95Ti0.05PO4, was synthesized by a solid-state reaction method. XRD and VTR were used to characterize the as-prepared samples. As a cathode material for lithium-ion batteries, Li0.95Fe0.95Ti0.05PO4 exhibited improved rate capability.
文摘Ti-doped WO3 films were prepared by the mid-frequency dual-target magnetron sputtering method. The structure and electrochromic properties of the Ti-doped WO3 films were analysed by X-Ray diffraction （XRD）, Raman spectroscopy, spectrophotometer, cyclic chronoam- perometry and atomic force microscopy （AFM）. The results indicate that the erystallinity decrease after the doping of titanium, the channels for ion injection and extraction increase, the responding speed with 5.1% titanium doped becomes faster, and its circle life increases more than four times compared with the undoped WO3 film. In the coloured state, the W-O-W bonds decrease, but the W = O bonds increase. Since the W-O-W bonds break down for Li＋ ions＇ injection and more W = O bonds form, it is more convenient to inject Li＋ ions into the Ti-doped film than undoped film because more W-O-W bonds break down in the coloured state.
基金supported by the National Natural Science Foundation of China (Grant Nos.60771019 and 60801018)the Tianjin Key Research Program of Application Foundation and Advanced Technology,China (Grant No.11JCZDJC15300)+1 种基金the Tianjin Natural Science Foundation,China (Grant No.09JCYBJC01100)the New Teacher Foundation of the Ministry of Education,China (Grant No.200800561109)
文摘Density functional theory （DFT） calculations are conducted to explore the interaction of H2 with pure and Tidoped WO3 （002） surfaces. Four top adsorption models of H2 on pure and Ti-doped WO3 （002） surfaces are investigated respectively, they are adsorption on bridging oxygen Olc, absorption on plane oxygen O2c, absorption on 5-fold W5c （Ti）, and absorption on 6-fold W6c. The most stable and H2 possible adsorption structure in the pure surface is H-end oriented to the surface plane oxygen O2c site, while the favourable adsorption sites for H2 in a Ti-doped surface is not only an O2c site but also a W6c site. The adsorption energy, the Fermi energy level EF, and the electronic population are investigated and the H2-sensing mechanism of a pure-doped WO3 （002） surface is revealed theoretically： the theoretical results are in good accordance with our existing experimental results. By comparing the above three terms, it is found that Ti doping can obviously enhance the adsorption of H2. It can be predicted that the method of Ti-doped into a WO3 thin film is an effective way to improve WO3 sensor sensitivity to H2 gas.
基金the National Natural Science Foundation of China (No. 50842028)the National High-Tech Research and Development Program of China (No. 2006AA03Z436).
文摘Ti-Modified (Na0.5K0.5)(TixNb1-x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures,and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction re-sults indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and...
文摘We experimentally compare the output abilities of lightly and heavily doped Ti：Sapphire（Ti：S） amplifiers with diameters as large as 150 mm. Although a lightly doped Ti：S is more favorable to overcome parasitic lasing（PL）and transverse amplified spontaneous emission（TASE）, the self-phase-modulation（SPM） effect becomes more pronounced when a longer crystal is used. Recompression of the amplified, stretched pulses can be seriously affected by the SPM effect. We then propose a temporal multi-pulse pump scheme to suppress PL and TASE in a thin, heavily doped Ti：S crystal. This novel temporal multi-pulse pump technique can find potential applications in 10 PW chirped-pulse amplification laser systems.
基金supported by the Xinjiang Science and Technology Program(2023TSYCCX0118)the Bingtuan Science and Technology Program(No.2023AB033).
文摘Bimetallic layered double hydroxides(LDHs)have attracted substantial attention as oxygen evolution reaction(OER)catalysts.In this work,we provide a facile route to prepare Ti-doped NiCo-LDH/NF electrocatalysts with M–O–Ti(M=Ni,Co)covalent bonds via a rapid immersion method for the OER process.The experiments and density functional theory(DFT)calculations elucidate that the doping of Ti(M–O–Ti)not only exfoliates the NiCo-LDH nanosheets into spheres but also causes lattice distortion to produce more oxygen vacancies,which promotes faster exchange of intermediates and improves the electron transfer efficiency.These superior physical characters endow Ti-NiCo-LDH with an excellent overpotential of 319 mV at a current density of 50 mA cm^(-2),which is markedly lower than that of NiCo-LDH(391 mV at 50 mA cm^(-2)).Even at a high current density of 100 mA cm^(-2),NiCo-LDH displays an overpotential of 429 mV,whereas Ti-NiCo-LDH is capable of achieving an overpotential of 353 mV.Moreover,the water electrolyzer based on the Ti-NiCo-LDH bifunctional catalyst requires a low cell voltage of 1.60 V to achieve a current density of 10 mA cm^(-2),and the Ti-NiCo-LDH catalyst has been successfully applied for solar cell-driven water electrolysis and the corresponding voltage is about 1.61 V.This work offers a novel strategy to fabricate high activity NiCo-LDH with rich oxygen vacancies toward the OER process.
基金supported by the Zibo Key Research and Development Project(Grant Nos.2020XCCG0106 and 2021SNPT0004)。
文摘High-power laser systems require thin films with extremely low absorption.Ultra-low-absorption films are often fabricated via ion beam sputtering,which is costly and slow.This study analyzes the impact of doping titanium and annealing on the absorption characteristics of thin films,focusing on composition and structure.The results indicate that the primary factor influencing absorption is composition.Suppressing the presence of electrons or holes that do not form stable chemical bonds can significantly reduce absorption;for amorphous thin films,the structural influence on absorption is relatively minor.Thus,composition control is crucial for fabricating ultra-low-absorption films,while the deposition method is secondary.Ion beam-assisted electron-beam evaporation,which is relatively seldom used for fabricating low-absorption films,was employed to produce high-reflectivity films.After annealing,the absorption at1064 nm reached 1.70 parts per million.This method offers a cost-effective and rapid approach for fabricating ultra-lowabsorption films.
基金This work is financially supported by the National Key R&D Program of China(No.2017YFE0198100)the National Natural Science Foundation of China(Nos.21975250 and 52072145)+4 种基金the Beijing Natural Science Foundation(No.2214061)the Scientific and Technological Developing Project of Jilin Province,China(No.YDZJ202101ZYTS185)the Capital Construction Fund Projects within the Budget of Jilin Province,China(No.2021C037-2)the Open Project Program of Key Laboratory of Preparation and Application of Environmental Friendly Materials(Jilin Normal University),Ministry of Education,China(No.2020005)the Open Program of State Key Laboratory of Metastable Materials Science and Technology(Yanshan University),China(No.202110).
文摘High-voltage high-nickel lithium layered oxide cathodes show great application prospects to meet the ever-increasing demand for further improvement of the energy density of rechargeable lithium-ion batteries(LIBs)mainly due to their high output capacity.However,severe bulk structural degradation and undesired electrode-electrolyte interface reactions seriously endanger the cycle life and safety of the battery.Here,2 mol%Ti atom is used as modified material doping into LiNi_(0.8)Co_(0.2)Mn_(0.2O2)(NCM)to reform LiNi_(0.6)Co_(0.2)Mn_(0.18)Ti_(0.02)O_(2)(NCM-Ti)and address the long-standing inherent problem.At a high cut-off voltage of 4.5 V,NCM-Ti delivers a higher capacity retention ratio(91.8%vs.82.9%)after 150 cycles and a superior rate capacity(118 vs.105 mAh·g^(-1))at the high current density of 10 C than the pristine NCM.The designed high-voltage full battery with graphite as anode and NCM-Ti as cathode also exhibits high energy density(240 Wh·kg^(-1))and excellent electrochemical performance.The superior electrochemical behavior can be attributed to the improved stability of the bulk structure and the electrode-electrolyte interface owing to the strong Ti-O bond and no unpaired electrons.The in-situ X-ray diffraction analysis demonstrates that Ti-doping inhibits the undesired H2-H3 phase transition,minimizing the mechanical degradation.The ex-situ TEM and X-ray photoelectron spectroscopy reveal that Ti-doping suppresses the release of interfacial oxygen,reducing undesired interfacial reactions.This work provides a valuable strategic guideline for the application of high-voltage high-nickel cathodes in LIBs.
