Sodium titanium phosphate(NaTi_(2)(PO_(4))_(3),NTP)has emerged as a promising electrode material due to its three-dimensional open framework.This study investigates the use of NTP in aqueous dilute Li^(+)/Na^(+)electr...Sodium titanium phosphate(NaTi_(2)(PO_(4))_(3),NTP)has emerged as a promising electrode material due to its three-dimensional open framework.This study investigates the use of NTP in aqueous dilute Li^(+)/Na^(+)electrolytes and extends its application to high-concentration K+electrolytes.X-ray photoelectron spectroscopy,X-ray absorption near-edge structure analysis,and density functional theory calculations revealed that highly electronegative fluorine partially substitutes for oxygen in the NTP lattice,resulting in the formation of Ti-F bonds.The substitution effectively modulates the electronic structure of Ti^(4+),alters the local coordination environment,and influences the redox dynamics.Enhanced long-term cycling stability and rate performance were demonstrated across aqueous sodium-ion,lithium-ion,and potassium-ion half-cells.Among the investigated systems,the aqueous sodium-ion system exhibited the best electrochemical performance,characterized by a single,well-defined charge–discharge plateau,stable cycling behavior with 88.7%capacity retention after 500 cycles at 1 A g^(−1),and an initial specific discharge capacity of 121.7 mAh g^(−1) at 0.2 A g^(−1).The results establish F-doped NTP as a promising candidate for advanced energy storage applications in aqueous alkali metal-ion batteries.展开更多
在MP2水平上采用6-311G基组计算了van der Waals复合物X…H2O(X=Li,Na,K)的非线性光学性质(μα,β),讨论了基组效应和电子相关效应对计算结果的贡献．在MP2／6-311++G(2df,2pd)水平上计算得到的三个复合物分子X(X=Li,Na,K)…H2O的非线...在MP2水平上采用6-311G基组计算了van der Waals复合物X…H2O(X=Li,Na,K)的非线性光学性质(μα,β),讨论了基组效应和电子相关效应对计算结果的贡献．在MP2／6-311++G(2df,2pd)水平上计算得到的三个复合物分子X(X=Li,Na,K)…H2O的非线性光学性质．结果表明,三种复合物分子均具有巨大的一阶超极化率,其中最外层电子的弥散特性对一阶超极化率有很大的影响．展开更多
As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells(ITSOFC), samarium-doped ceria(SDC)–Li Na SO4nano-composites were synthesized by a sol–gel method and their properties were i...As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells(ITSOFC), samarium-doped ceria(SDC)–Li Na SO4nano-composites were synthesized by a sol–gel method and their properties were investigated. It was found that the content of Li Na SO4 strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of Li Na SO4 was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm-1at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm-2at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC–Li Na SO4(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC–Li Na SO4 composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability.展开更多
采用相图计算(CALPHAD:Calculation of phase diagrams)方法对Zr-X(X=Li,Na,K,Sc,Hf)5个二元体系进行了相图热力学研究.基于实验数据,通过热力学优化计算获得了一套描述液相及(αZr),(βZr),(Li),(Na),(K),(αSc),(βSc),(αHf)和(βHf...采用相图计算(CALPHAD:Calculation of phase diagrams)方法对Zr-X(X=Li,Na,K,Sc,Hf)5个二元体系进行了相图热力学研究.基于实验数据,通过热力学优化计算获得了一套描述液相及(αZr),(βZr),(Li),(Na),(K),(αSc),(βSc),(αHf)和(βHf)相的热力学参数.Zr-Li,Zr-Na和Zr-K体系中的气相视为理想气体.与实验相图数据对比发现,本文获得的热力学参数能够准确地描述实验相平衡数据.展开更多
基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究。通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热...基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究。通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数。V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体。与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据。展开更多
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
基金supported by the National Natural Science Foundation of China(52072298,51802261,11675129)the Natural Science Basic Research Plan in Shaanxi Province of China(2025JC-YBQN-758)+1 种基金Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.23JK0662)the Youth Innovation Team of Shaanxi Universities.
文摘Sodium titanium phosphate(NaTi_(2)(PO_(4))_(3),NTP)has emerged as a promising electrode material due to its three-dimensional open framework.This study investigates the use of NTP in aqueous dilute Li^(+)/Na^(+)electrolytes and extends its application to high-concentration K+electrolytes.X-ray photoelectron spectroscopy,X-ray absorption near-edge structure analysis,and density functional theory calculations revealed that highly electronegative fluorine partially substitutes for oxygen in the NTP lattice,resulting in the formation of Ti-F bonds.The substitution effectively modulates the electronic structure of Ti^(4+),alters the local coordination environment,and influences the redox dynamics.Enhanced long-term cycling stability and rate performance were demonstrated across aqueous sodium-ion,lithium-ion,and potassium-ion half-cells.Among the investigated systems,the aqueous sodium-ion system exhibited the best electrochemical performance,characterized by a single,well-defined charge–discharge plateau,stable cycling behavior with 88.7%capacity retention after 500 cycles at 1 A g^(−1),and an initial specific discharge capacity of 121.7 mAh g^(−1) at 0.2 A g^(−1).The results establish F-doped NTP as a promising candidate for advanced energy storage applications in aqueous alkali metal-ion batteries.
文摘在MP2水平上采用6-311G基组计算了van der Waals复合物X…H2O(X=Li,Na,K)的非线性光学性质(μα,β),讨论了基组效应和电子相关效应对计算结果的贡献．在MP2／6-311++G(2df,2pd)水平上计算得到的三个复合物分子X(X=Li,Na,K)…H2O的非线性光学性质．结果表明,三种复合物分子均具有巨大的一阶超极化率,其中最外层电子的弥散特性对一阶超极化率有很大的影响．
基金supported by the Natural Science Foundation of China(21173147 and 21376143)973 Program of China(2014CB239700)
文摘As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells(ITSOFC), samarium-doped ceria(SDC)–Li Na SO4nano-composites were synthesized by a sol–gel method and their properties were investigated. It was found that the content of Li Na SO4 strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of Li Na SO4 was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm-1at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm-2at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC–Li Na SO4(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC–Li Na SO4 composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability.
文摘采用相图计算(CALPHAD:Calculation of phase diagrams)方法对Zr-X(X=Li,Na,K,Sc,Hf)5个二元体系进行了相图热力学研究.基于实验数据,通过热力学优化计算获得了一套描述液相及(αZr),(βZr),(Li),(Na),(K),(αSc),(βSc),(αHf)和(βHf)相的热力学参数.Zr-Li,Zr-Na和Zr-K体系中的气相视为理想气体.与实验相图数据对比发现,本文获得的热力学参数能够准确地描述实验相平衡数据.
文摘基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究。通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数。V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体。与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据。
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。
