Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibri...Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibrium analysis of Mn^(2+)-Fe^(2+)-Mg^(2+)-C_(2)O_(4)^(2-)-H_(2)O system is used to guide the design and preparation of insitu Mg-doped(Fe_(0.4)Mn_(0.6))_(1-x)Mg_(x)C_(2)O_(4)intermediate,which is then employed as an innovative precursor to synthesize high-performance Mg-doped LiFe_(0.4)Mn_(0.6)PO_(4).It indicates that the metal ions with a high precipitation efficiency and the stoichiometric precursors with uniform element distribution can be achieved under the optimized thermodynamic conditions.Meanwhile,accelerated Li+diffusivity and reduced charge transfer resistance originating from Mg doping are verified by various kinetic characterizations.Benefiting from the contributions of inherited homogeneous element distribution,small particle size,uniform carbon layer coating,enhanced Li+migration ability and structural stability induced by Mg doping,the Li(Fe_(0.4)Mn_(0.6))_(0.97)Mg_(0.03)PO_(4)/C exhibits splendid electrochemical performance.展开更多
采用固相反应法制备了Mg_(1-x)Cu_xFe_2O_4(x=0,0.4,0.6和0.8)系多晶铁氧体,分别采用X射线衍射(XRD)、扫描电镜(SEM)和振动样品磁强计(VSM)对样品的结构和静态磁性能进行了表征,并测试了磁环在10k Hz^1MHz范围的磁导率、品质因数以及功...采用固相反应法制备了Mg_(1-x)Cu_xFe_2O_4(x=0,0.4,0.6和0.8)系多晶铁氧体,分别采用X射线衍射(XRD)、扫描电镜(SEM)和振动样品磁强计(VSM)对样品的结构和静态磁性能进行了表征,并测试了磁环在10k Hz^1MHz范围的磁导率、品质因数以及功率损耗。结果表明,Cu含量x=0~0.6时,样品均为单相立方尖晶石结构,Cu含量进一步增加至x=0.8时呈现大量的四方相另相;晶粒尺寸和密度均随x值增加逐渐增大,而电阻率则呈减小趋势;饱和磁化强度由20.7 A m2/kg逐渐增大到30.4 A m2/kg,矫顽力先减小后增大,在x=0.6时具有最小值445.7 A/m。利用适量的Cu2+取代Mg2+可以提高Mg1-xCuxFe2O4铁氧体的磁导率并降低其品质因数,样品的功耗相应地明显增大;在交变磁场频率为370k Hz时,磁通密度低于20 m T范围内,Mg_(0.4)Cu_(0.6)Fe_2O_4具有相对较高的功耗。展开更多
基金The Project was Supported by Nature Science Foundation of Minstry of Education of Shaanxi Province(09JK718)Scientific Research Foundation of Xi'an Institute of Post and Telecom(ZL2009-32)
基金financially supported by the National Natural Science Foundation of China(No.51904250)the China Postdoctoral Science Foundation(No.2021M692254)+2 种基金the Sichuan Science and Technology Program(No.2022YFG0098)the Fundamental Research Funds for the Central Universities(Nos.2021CDSN-02,2022SCU12002,2022CDZG-17,2022CDSN-08,2022CDZG-9)the Hohhot Science and Technology Program(No.2023-Jie Bang Gua Shuai-Gao-3)。
文摘Mn-rich LiFe_(1-x)Mn_(x)PO_(4)(x>0.5),which combines the high operation voltage of LiMnPO_(4)with excellent rate performa nce of LiFePO4,is hindered by its sluggish kinetic properties.Herein,thermodynamic equilibrium analysis of Mn^(2+)-Fe^(2+)-Mg^(2+)-C_(2)O_(4)^(2-)-H_(2)O system is used to guide the design and preparation of insitu Mg-doped(Fe_(0.4)Mn_(0.6))_(1-x)Mg_(x)C_(2)O_(4)intermediate,which is then employed as an innovative precursor to synthesize high-performance Mg-doped LiFe_(0.4)Mn_(0.6)PO_(4).It indicates that the metal ions with a high precipitation efficiency and the stoichiometric precursors with uniform element distribution can be achieved under the optimized thermodynamic conditions.Meanwhile,accelerated Li+diffusivity and reduced charge transfer resistance originating from Mg doping are verified by various kinetic characterizations.Benefiting from the contributions of inherited homogeneous element distribution,small particle size,uniform carbon layer coating,enhanced Li+migration ability and structural stability induced by Mg doping,the Li(Fe_(0.4)Mn_(0.6))_(0.97)Mg_(0.03)PO_(4)/C exhibits splendid electrochemical performance.
文摘采用固相反应法制备了Mg_(1-x)Cu_xFe_2O_4(x=0,0.4,0.6和0.8)系多晶铁氧体,分别采用X射线衍射(XRD)、扫描电镜(SEM)和振动样品磁强计(VSM)对样品的结构和静态磁性能进行了表征,并测试了磁环在10k Hz^1MHz范围的磁导率、品质因数以及功率损耗。结果表明,Cu含量x=0~0.6时,样品均为单相立方尖晶石结构,Cu含量进一步增加至x=0.8时呈现大量的四方相另相;晶粒尺寸和密度均随x值增加逐渐增大,而电阻率则呈减小趋势;饱和磁化强度由20.7 A m2/kg逐渐增大到30.4 A m2/kg,矫顽力先减小后增大,在x=0.6时具有最小值445.7 A/m。利用适量的Cu2+取代Mg2+可以提高Mg1-xCuxFe2O4铁氧体的磁导率并降低其品质因数,样品的功耗相应地明显增大;在交变磁场频率为370k Hz时,磁通密度低于20 m T范围内,Mg_(0.4)Cu_(0.6)Fe_2O_4具有相对较高的功耗。
