Ni-rich cathode materials have become one of the most promising cathode materials for advanced high-energy Li-ion batteries(LIBs)owing to their high specific capacity.However,Ni-rich cathode materials are sensitive to...Ni-rich cathode materials have become one of the most promising cathode materials for advanced high-energy Li-ion batteries(LIBs)owing to their high specific capacity.However,Ni-rich cathode materials are sensitive to the trace H2O and CO2 in the air,and tend to react with them to generate LiOH and Li2COg at the particle surface region(named residual lithium compounds,labeled as RLCs).The RLCs will deteriorate the comprehensive performances of Ni-rich cathode materials and make trouble in the subsequent manufacturing process of electrode,including causing low initial coulombic efficiency and poor storage property,bringing about potential safety hazards,and gelatinizing the electrode slurry.Therefore,it is of considerable significance to remove the RLCs.Researchers have done a lot of work on the corresponding field,such as exploring the formation mechanism and elimination methods.This paper investigates the origin of the surface residual lithium compounds on Ni-rich cathode materials,analyzes their adverse effects on the per-formance and the subsequent electrode production process,and summarizes various kinds of feasible methods for removing the RLCS.Finally,we propose a new research direction of eliminating the lithium residuals after comparing and summing up the above.We hope this work can provide a reference for alleviating the adverse effects of residual lithium compounds for Ni-rich cathode materials'industrial production.展开更多
Previous studies have found that the ceramic fuel cell using Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2)(NCAL)symmetrical electrode has obtained very good power generation performance in the temperature range of 450 to 550℃.Pr...Previous studies have found that the ceramic fuel cell using Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2)(NCAL)symmetrical electrode has obtained very good power generation performance in the temperature range of 450 to 550℃.Previous studies have pointed out that after being reduced by H2,NCAL anode will produce LiOH/Li2CO3 mixture and diffuse into the electrolyte,which results in the high ionic conductivity of the cell.In this study,the chemical reactivity of different oxide electrolytes such as CeO_(2),TiO_(2),ZrO_(2)and YSZ with LiOH and/or Li2CO3 and their effects on the electrochemical performance of the cell were studied.It is found that at 550◦C,only the open circuit voltage(OCV)of the cell using CeO_(2)as electrolyte can remain stable,and the maximum power density(MPD)of the CeO_(2)electrolyte cell reaches 599.6 mW⋅cm^(−2).The OCV of the cells with TiO_(2),ZrO_(2)and YSZ as electrolyte increased to the highest value within a few minutes,and the MPD of the cells was only more than 12 mW⋅cm^(−2).XRD,FT-IR,SEM-EDS and ICP-OES results indicate that the LiOH/Li2CO3 mixture diffuses into TiO_(2),ZrO_(2)and YSZ electrolytes and reacts with three oxides to produce Li2TiO3 and Li2ZrO3,respectively,which results in the low performance of the cell.展开更多
The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦...The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦C and constant current density of 0.2 A⋅cm^(-2),the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable.After 10 h,the voltage of the cell began to decrease gradually,and by 50 h,the voltage had decreased to 0.522 V.The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM,TOF-SIMS and FTIR indicate that the distribution of Li_(2)O/LiOH/Li_(2)CO_(3)compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell.The dynamic migration of molten salt destroyed the continuity of molten salt in the cell,which in turn adversely impacted the ionic conductivity of electrolyte,gas tightness of the cell,and electrochemical reactions on both sides of the cathode and anode.These finally lead to the degradation of the cell performance.展开更多
Li[Li0.2Ni0.13Coo.13Mn0.54]O2 cathode materials were synthesized by carbonate-based co-precipitation method, and then, its surface was coated by thin layers of FePO4. The prepared samples were characterized by X-ray d...Li[Li0.2Ni0.13Coo.13Mn0.54]O2 cathode materials were synthesized by carbonate-based co-precipitation method, and then, its surface was coated by thin layers of FePO4. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron micro- scope （FESEM）, energy-dispersive spectroscopy （EDS）, and transmission electron microscopy （TEM）. The XRD and TEM results suggest that both the pristine and the coated materials have a hexagonal layered structure, and the FePO4 coating layer does not make any major change in the crystal structure. The FePO4-coated sample exhibits both improved initial discharge capacity and columbic efficiency compared to the pristine one. More significantly, the FePO4 coating layer has a much positive influence on the cycling perfor- mance. The FePO4-coated sample exhibits capacity reten- tion of 82 % after 100 cycles at 0.5℃ between 2.0 and 4.8 V, while only 28 % for the pristine one at the same charge-discharge condition. The electrochemical impe- dance spectroscopy （EIS） results indicate that this improved cycling performance could be ascribed to the presence of FePO4 on the surface of Li[Li0.2Ni0.13Co0.13Mno.54102 par- ticle, which helps to protect the cathode from chemical attacks by HF and thus suppresses the large increase in charge transfer resistance.展开更多
A high alkali reactive aggregate zeolitization perlite was used to test the long term effectiveness of LiOH in inhibiting alkali silica reaction.In this paper,the rigorous conditions were designed that the mortar b...A high alkali reactive aggregate zeolitization perlite was used to test the long term effectiveness of LiOH in inhibiting alkali silica reaction.In this paper,the rigorous conditions were designed that the mortar bars had been cured at 80℃ for 3 years after autoclaved 24 hours at 150℃.Under this condition,LiOH was able to inhibit the alkali silica reaction long term effectiveness.Not only the relationship between the molar ratio of n(Li)/(Na) and the alkali contents in systems was established, but also the governing mechanism of such effects was also studied by SEM.展开更多
Lithium tetraborate(LB4)is a lithium borate compound known for its exceptional linear and nonlinear optical properties,including a wide transparency range(0.16–3.5μm)and high Raman gain.Here,a millimeter-sized LB4 w...Lithium tetraborate(LB4)is a lithium borate compound known for its exceptional linear and nonlinear optical properties,including a wide transparency range(0.16–3.5μm)and high Raman gain.Here,a millimeter-sized LB4 whispering gallery mode(WGM)resonator with a record quality factor of 2.0×10^(9) at 517 nm was fabricated using single-point diamond cutting.Pumped with about 10 m W at 517 nm,it demonstrated four cascaded stimulated Raman scattering(SRS)peaks(537–608 nm),with the first-order SRS achieving a threshold of 0.71 m W and 7.2% slope efficiency.To our knowledge,this marks the first LB4 WGM resonator Raman laser.展开更多
The direct fourth harmonic generation (FHG) is theoretically demonstrated based on quasi-phase-matching (QPM) configuration in periodically poled lithium tantalate (PPLT). The wavelength dependence of the period of FH...The direct fourth harmonic generation (FHG) is theoretically demonstrated based on quasi-phase-matching (QPM) configuration in periodically poled lithium tantalate (PPLT). The wavelength dependence of the period of FHG QPM gratings is calculated. Bandwidths of fundamental wavelength, temperature, and incident angle are also studied. A very wide bandwidth, as large as 119.5 nm, of fundamental wavelength near 3699 nm is found with the QPM period of 9.442 μm and the crystal length of 1 cm.展开更多
We demonstrate an efficiency-enhanced picosecond （ps） mid-infrared radiation via optical parametric downconversion. Based on a cascaded periodically poled MgO-doped stoiehiometric lithium tantalate crystal （MgO：sP...We demonstrate an efficiency-enhanced picosecond （ps） mid-infrared radiation via optical parametric downconversion. Based on a cascaded periodically poled MgO-doped stoiehiometric lithium tantalate crystal （MgO：sPPLT）, a tandem optical parametric oscillation-optical parametric amplification （OPO-OPA） process is achieved. Compared with a single OPO process, the conversion efficiency obtains an enhancement of 71%.展开更多
基金This work was supported by the National Key R&D Program of China(No.2016YFB0100301)the National Natural Science Foun dation of China(Nos.21875022,51802020,U1664255)+2 种基金the Science and Technology Innovation Foundation of Beijing Institute of Technology Chongqing Innovation Center(No.2020CX5100006)the Young Elite Scientists Sponsorship Program by CAST(No.2018QNRC001)L.Chen and N.Li acknowledge the support from the Bejing Institute of Technology Research Fund Program for Young Scholars.
文摘Ni-rich cathode materials have become one of the most promising cathode materials for advanced high-energy Li-ion batteries(LIBs)owing to their high specific capacity.However,Ni-rich cathode materials are sensitive to the trace H2O and CO2 in the air,and tend to react with them to generate LiOH and Li2COg at the particle surface region(named residual lithium compounds,labeled as RLCs).The RLCs will deteriorate the comprehensive performances of Ni-rich cathode materials and make trouble in the subsequent manufacturing process of electrode,including causing low initial coulombic efficiency and poor storage property,bringing about potential safety hazards,and gelatinizing the electrode slurry.Therefore,it is of considerable significance to remove the RLCs.Researchers have done a lot of work on the corresponding field,such as exploring the formation mechanism and elimination methods.This paper investigates the origin of the surface residual lithium compounds on Ni-rich cathode materials,analyzes their adverse effects on the per-formance and the subsequent electrode production process,and summarizes various kinds of feasible methods for removing the RLCS.Finally,we propose a new research direction of eliminating the lithium residuals after comparing and summing up the above.We hope this work can provide a reference for alleviating the adverse effects of residual lithium compounds for Ni-rich cathode materials'industrial production.
基金the National Natural Science Foundation of China(No.21978044,No.51834004)。
文摘Previous studies have found that the ceramic fuel cell using Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2)(NCAL)symmetrical electrode has obtained very good power generation performance in the temperature range of 450 to 550℃.Previous studies have pointed out that after being reduced by H2,NCAL anode will produce LiOH/Li2CO3 mixture and diffuse into the electrolyte,which results in the high ionic conductivity of the cell.In this study,the chemical reactivity of different oxide electrolytes such as CeO_(2),TiO_(2),ZrO_(2)and YSZ with LiOH and/or Li2CO3 and their effects on the electrochemical performance of the cell were studied.It is found that at 550◦C,only the open circuit voltage(OCV)of the cell using CeO_(2)as electrolyte can remain stable,and the maximum power density(MPD)of the CeO_(2)electrolyte cell reaches 599.6 mW⋅cm^(−2).The OCV of the cells with TiO_(2),ZrO_(2)and YSZ as electrolyte increased to the highest value within a few minutes,and the MPD of the cells was only more than 12 mW⋅cm^(−2).XRD,FT-IR,SEM-EDS and ICP-OES results indicate that the LiOH/Li2CO3 mixture diffuses into TiO_(2),ZrO_(2)and YSZ electrolytes and reacts with three oxides to produce Li2TiO3 and Li2ZrO3,respectively,which results in the low performance of the cell.
基金supported by the National Natural Science Foundation of China(No.21978044).
文摘The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦C and constant current density of 0.2 A⋅cm^(-2),the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable.After 10 h,the voltage of the cell began to decrease gradually,and by 50 h,the voltage had decreased to 0.522 V.The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM,TOF-SIMS and FTIR indicate that the distribution of Li_(2)O/LiOH/Li_(2)CO_(3)compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell.The dynamic migration of molten salt destroyed the continuity of molten salt in the cell,which in turn adversely impacted the ionic conductivity of electrolyte,gas tightness of the cell,and electrochemical reactions on both sides of the cathode and anode.These finally lead to the degradation of the cell performance.
基金financially supported by NSAF(No.U1530155)Ministry of Science and Technology(MOST)of China,US–China Collaboration on Cutting-edge Technology Development of Electric Vehicle,the Nation Key Basic Research Program of China(No.2015CB251100)Beijing Key Laboratory of Environmental Science and Engineering(No.20131039031)
基金financially supported by the National Nature Science Foundation of China (No.51302017)the National High Technology Research and Development Program of China (No.2012AA110102)the fund from the Science and Technology Commission of Beijing (No.2121100006712002)
文摘Li[Li0.2Ni0.13Coo.13Mn0.54]O2 cathode materials were synthesized by carbonate-based co-precipitation method, and then, its surface was coated by thin layers of FePO4. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron micro- scope （FESEM）, energy-dispersive spectroscopy （EDS）, and transmission electron microscopy （TEM）. The XRD and TEM results suggest that both the pristine and the coated materials have a hexagonal layered structure, and the FePO4 coating layer does not make any major change in the crystal structure. The FePO4-coated sample exhibits both improved initial discharge capacity and columbic efficiency compared to the pristine one. More significantly, the FePO4 coating layer has a much positive influence on the cycling perfor- mance. The FePO4-coated sample exhibits capacity reten- tion of 82 % after 100 cycles at 0.5℃ between 2.0 and 4.8 V, while only 28 % for the pristine one at the same charge-discharge condition. The electrochemical impe- dance spectroscopy （EIS） results indicate that this improved cycling performance could be ascribed to the presence of FePO4 on the surface of Li[Li0.2Ni0.13Co0.13Mno.54102 par- ticle, which helps to protect the cathode from chemical attacks by HF and thus suppresses the large increase in charge transfer resistance.
文摘A high alkali reactive aggregate zeolitization perlite was used to test the long term effectiveness of LiOH in inhibiting alkali silica reaction.In this paper,the rigorous conditions were designed that the mortar bars had been cured at 80℃ for 3 years after autoclaved 24 hours at 150℃.Under this condition,LiOH was able to inhibit the alkali silica reaction long term effectiveness.Not only the relationship between the molar ratio of n(Li)/(Na) and the alkali contents in systems was established, but also the governing mechanism of such effects was also studied by SEM.
基金Royal Society of New Zealand Marsden Council fund(20UOO-080)。
文摘Lithium tetraborate(LB4)is a lithium borate compound known for its exceptional linear and nonlinear optical properties,including a wide transparency range(0.16–3.5μm)and high Raman gain.Here,a millimeter-sized LB4 whispering gallery mode(WGM)resonator with a record quality factor of 2.0×10^(9) at 517 nm was fabricated using single-point diamond cutting.Pumped with about 10 m W at 517 nm,it demonstrated four cascaded stimulated Raman scattering(SRS)peaks(537–608 nm),with the first-order SRS achieving a threshold of 0.71 m W and 7.2% slope efficiency.To our knowledge,this marks the first LB4 WGM resonator Raman laser.
文摘The direct fourth harmonic generation (FHG) is theoretically demonstrated based on quasi-phase-matching (QPM) configuration in periodically poled lithium tantalate (PPLT). The wavelength dependence of the period of FHG QPM gratings is calculated. Bandwidths of fundamental wavelength, temperature, and incident angle are also studied. A very wide bandwidth, as large as 119.5 nm, of fundamental wavelength near 3699 nm is found with the QPM period of 9.442 μm and the crystal length of 1 cm.
基金supported by the International Science and Technology Cooperation Program of China(ISTCP) (No.2014DFT50230)the National Key Scientific Instrument and Equipment Development Project (No.2011YQ030127)the National Natural Science Foundation of China(No.61405133)
文摘We demonstrate an efficiency-enhanced picosecond （ps） mid-infrared radiation via optical parametric downconversion. Based on a cascaded periodically poled MgO-doped stoiehiometric lithium tantalate crystal （MgO：sPPLT）, a tandem optical parametric oscillation-optical parametric amplification （OPO-OPA） process is achieved. Compared with a single OPO process, the conversion efficiency obtains an enhancement of 71%.
