以乙酸盐(乙酸锂、乙酸钠、乙酸钴、乙酸镍、乙酸锰等)为原材料,采用球磨辅助高温固相法制备Li_(1.0)Na_(0.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2正极材料。借助XRD、SEM等表征材料的结构和形貌,利用循环伏安、恒流充放电、交流阻抗等方法...以乙酸盐(乙酸锂、乙酸钠、乙酸钴、乙酸镍、乙酸锰等)为原材料,采用球磨辅助高温固相法制备Li_(1.0)Na_(0.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2正极材料。借助XRD、SEM等表征材料的结构和形貌,利用循环伏安、恒流充放电、交流阻抗等方法研究材料的电化学性能。结果表明,钠的掺杂导致颗粒表面光滑度降低,形成Na_(0.77)Mn O_(2.05)新相。0.05C活化过程中,掺钠样品和未掺钠样品首次放电比容量分别为258.4 m Ah·g^(-1)和215.8 m Ah·g^(-1),库伦效率分别为75.2%和72.8%;2C放电比容量分别为116.3 m Ah·g^(-1)和106.2 m Ah·g^(-1)。研究发现,掺钠可减小首次充放电过程的不可逆容量,提高容量保持率;改善倍率性能与容量恢复特性;降低SEI膜阻抗和电荷转移阻抗;掺钠后样品首次循环就可以基本完成Li_2Mn O_3组分向稳定结构的转化,而未掺杂的样品需要两次循环才能逐步完成该过程;XPS结果表明,掺钠样品中Ni^(2+)、Co^(3+)、Mn^(4+)所占比例明显提高,改善了样品的稳定性和电化学性能;循环200次后的XRD结果表明掺钠与未掺钠材料在脱嵌锂反应中的相变化过程基本一致,良好有序的层状结构遭到破坏是循环过程中容量衰减的主要原因。展开更多
Undoped and Na-doped ZnO films were deposited by sol-gel method.The effects of sodium incorporation on structure,surface morphology and optical constants of the films were investigated.X-ray diffraction patterns show ...Undoped and Na-doped ZnO films were deposited by sol-gel method.The effects of sodium incorporation on structure,surface morphology and optical constants of the films were investigated.X-ray diffraction patterns show the hexagonal wurtzite polycrystalline structure and that the sodium incorporation leads to the change in the structural characteristics of ZnO films.The SEM observations show that the surface morphology of the films is affected by the sodium incorporation.The transmission spectra show that the average transmittance of the films is above 85% in the visible range.The absorption edge initially blue-shifts and then red-shifts with the increase of Na doping content.The optical constants of these films were calculated using transmission spectra.Refractive indices of the films in the visible range decrease at first and then increase with increasing Na doping content.展开更多
Na^＋ doped sample Li0.95Na0.05FePO4 was prepared through solid state method. Structure characterization shows Na^＋ is successfully introduced into the LiFePO4 matrix. Scanning electron microscopy shows the particle ...Na^＋ doped sample Li0.95Na0.05FePO4 was prepared through solid state method. Structure characterization shows Na^＋ is successfully introduced into the LiFePO4 matrix. Scanning electron microscopy shows the particle size mainly ranges in 1-3 μm. X-ray diffraction Rietveld refinement demonstrates lattice distortion with an increased cell volume. As one cathode material, it has a discharge capacity of 150 mAh/g at 0.1 C rate. The material exhibits a capacity of 109 and 107 mAh/g at 5 and 7.5 C respectively. When cycled at 1 and 5 C, the material retains 84% （after 1000 cycles） and 86% （after 350 cycles） of the initial discharge capacity respectively indicating excellent structure stability and cycling performance. Na^＋ doping enhances the electrochemical activity especially the cycle performance effectively.展开更多
Na-doped p-type ZnO thin films have been realized by DC reactive magnetron sputtering with a set of metal-Zn targets doped with various Na contents and under different substrate temperatures, respectively. Hall effect...Na-doped p-type ZnO thin films have been realized by DC reactive magnetron sputtering with a set of metal-Zn targets doped with various Na contents and under different substrate temperatures, respectively. Hall effect measurement, field-emission SEM, X-ray diffraction and optical transmission were carried out to investigate the effects of Na content and substrate temperature on the properties of p-type films. Results indicate that all the Na-doped ZnO films are strongly （002） oriented, and have an average transmittance -85 % in the visible region. Na-doped p-type ZnO films with good structural, electrical, and optical properties can only be obtained at an intermediate amount of Na content and under appropriate substrate temperature. At the optimal condition, the Na-doped p-type ZnO has the lowest resistivity of 13. 8 Ω· cm with the carrier concentration as high as 1.07 × 10^18 em^-3. The stability of the Na-doped p-type ZnO is also studied in this paper and it is found that the electrical properties keep stable in a period of one month.展开更多
We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization pro...We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.展开更多
Layer-structured O3 type cathode materials Na1-xCr1-xTixO2(x=0,0.03,0.05)are fabri-cated by a thermo-polymerization method.The structures and morphologies are characterized by X-ray diffraction(XRD)and scanning electr...Layer-structured O3 type cathode materials Na1-xCr1-xTixO2(x=0,0.03,0.05)are fabri-cated by a thermo-polymerization method.The structures and morphologies are characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM)respectively.It has been found that the appropriate Ti doping effectively leads to the formation of uniform morphology.As a cathode,the x=0.03 sample delivers a quite high discharge capacity of 110 mAh/g at 32 C in the voltage range from 2.0 V to 3.6 V(vs.Na/Na+)and with a capac-ity retention of 96%after 100 cycles at 0.2 C.The Na//Na0:97Cr0.97Ti0.03O2 cell exhibits very high coulombic efficiency(above 96%).All these results suggest that Na0:97Cr0.97Ti0.03O2 is very promising for high-rate sodium ion batteries.展开更多
文摘以乙酸盐(乙酸锂、乙酸钠、乙酸钴、乙酸镍、乙酸锰等)为原材料,采用球磨辅助高温固相法制备Li_(1.0)Na_(0.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2正极材料。借助XRD、SEM等表征材料的结构和形貌,利用循环伏安、恒流充放电、交流阻抗等方法研究材料的电化学性能。结果表明,钠的掺杂导致颗粒表面光滑度降低,形成Na_(0.77)Mn O_(2.05)新相。0.05C活化过程中,掺钠样品和未掺钠样品首次放电比容量分别为258.4 m Ah·g^(-1)和215.8 m Ah·g^(-1),库伦效率分别为75.2%和72.8%;2C放电比容量分别为116.3 m Ah·g^(-1)和106.2 m Ah·g^(-1)。研究发现,掺钠可减小首次充放电过程的不可逆容量,提高容量保持率;改善倍率性能与容量恢复特性;降低SEI膜阻抗和电荷转移阻抗;掺钠后样品首次循环就可以基本完成Li_2Mn O_3组分向稳定结构的转化,而未掺杂的样品需要两次循环才能逐步完成该过程;XPS结果表明,掺钠样品中Ni^(2+)、Co^(3+)、Mn^(4+)所占比例明显提高,改善了样品的稳定性和电化学性能;循环200次后的XRD结果表明掺钠与未掺钠材料在脱嵌锂反应中的相变化过程基本一致,良好有序的层状结构遭到破坏是循环过程中容量衰减的主要原因。
基金Project(50872001) supported by the National Natural Science Foundation of ChinaProject(20060357003) supported by Research Fund for the Doctoral Program of Higher Education of ChinaProject(KJ2010A284) supported by the Natural Science Foundation of Anhui Higher Education Institution of China
文摘Undoped and Na-doped ZnO films were deposited by sol-gel method.The effects of sodium incorporation on structure,surface morphology and optical constants of the films were investigated.X-ray diffraction patterns show the hexagonal wurtzite polycrystalline structure and that the sodium incorporation leads to the change in the structural characteristics of ZnO films.The SEM observations show that the surface morphology of the films is affected by the sodium incorporation.The transmission spectra show that the average transmittance of the films is above 85% in the visible range.The absorption edge initially blue-shifts and then red-shifts with the increase of Na doping content.The optical constants of these films were calculated using transmission spectra.Refractive indices of the films in the visible range decrease at first and then increase with increasing Na doping content.
基金V. ACKNOWLEDGMENTS The work was supported by the Natural Science Foundation of Anhui province （No.90414178） and USTC-NSRL Association funding （No.KY2060030010）.
文摘Na^＋ doped sample Li0.95Na0.05FePO4 was prepared through solid state method. Structure characterization shows Na^＋ is successfully introduced into the LiFePO4 matrix. Scanning electron microscopy shows the particle size mainly ranges in 1-3 μm. X-ray diffraction Rietveld refinement demonstrates lattice distortion with an increased cell volume. As one cathode material, it has a discharge capacity of 150 mAh/g at 0.1 C rate. The material exhibits a capacity of 109 and 107 mAh/g at 5 and 7.5 C respectively. When cycled at 1 and 5 C, the material retains 84% （after 1000 cycles） and 86% （after 350 cycles） of the initial discharge capacity respectively indicating excellent structure stability and cycling performance. Na^＋ doping enhances the electrochemical activity especially the cycle performance effectively.
基金Natural Science Foundation (60576063)Science and Technology Project of Zhejiang province(2008F70015)
文摘Na-doped p-type ZnO thin films have been realized by DC reactive magnetron sputtering with a set of metal-Zn targets doped with various Na contents and under different substrate temperatures, respectively. Hall effect measurement, field-emission SEM, X-ray diffraction and optical transmission were carried out to investigate the effects of Na content and substrate temperature on the properties of p-type films. Results indicate that all the Na-doped ZnO films are strongly （002） oriented, and have an average transmittance -85 % in the visible region. Na-doped p-type ZnO films with good structural, electrical, and optical properties can only be obtained at an intermediate amount of Na content and under appropriate substrate temperature. At the optimal condition, the Na-doped p-type ZnO has the lowest resistivity of 13. 8 Ω· cm with the carrier concentration as high as 1.07 × 10^18 em^-3. The stability of the Na-doped p-type ZnO is also studied in this paper and it is found that the electrical properties keep stable in a period of one month.
文摘We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.
基金supported by the National Natural Science Foundation of China Academy of Engineering Physics (No.U1630106)the National Natural Science Foundation of China (No.51577175)Education Ministry of Anhui Province (No.KJ2014ZD36)
文摘Layer-structured O3 type cathode materials Na1-xCr1-xTixO2(x=0,0.03,0.05)are fabri-cated by a thermo-polymerization method.The structures and morphologies are characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM)respectively.It has been found that the appropriate Ti doping effectively leads to the formation of uniform morphology.As a cathode,the x=0.03 sample delivers a quite high discharge capacity of 110 mAh/g at 32 C in the voltage range from 2.0 V to 3.6 V(vs.Na/Na+)and with a capac-ity retention of 96%after 100 cycles at 0.2 C.The Na//Na0:97Cr0.97Ti0.03O2 cell exhibits very high coulombic efficiency(above 96%).All these results suggest that Na0:97Cr0.97Ti0.03O2 is very promising for high-rate sodium ion batteries.
