Sodium-ion batteries(SIBs)have rapidly risen to the forefront of energy storage systems as a promising supplementary for Lithium-ion batteries(LIBs).Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)as a common cathode of SIBs,featur...Sodium-ion batteries(SIBs)have rapidly risen to the forefront of energy storage systems as a promising supplementary for Lithium-ion batteries(LIBs).Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)as a common cathode of SIBs,features the merits of high operating voltage,small volume change and favorable specific energy density.However,it suffers from poor cycling stability and rate performance induced by its low intrinsic conductivity.Herein,we propose an ingenious strategy targeting superior SIBs through cross-linked NVPF with multi-dimensional nanocarbon frameworks composed of amorphous carbon and carbon nanotubes(NVPF@C@CNTs).This rational design ensures favorable particle size for shortened sodium ion transmission pathway as well as improved electronic transfer network,thus leading to enhanced charge transfer kinetics and superior cycling stability.Benefited from this unique structure,significantly improved electrochemical properties are obtained,including high specific capacity(126.9 mAh g^(-1)at 1 C,1 C=128 mA g^(-1))and remarkably improved long-term cycling stability with 93.9%capacity retention after 1000 cycles at 20 C.The energy density of 286.8 Wh kg^(-1)can be reached for full cells with hard carbon as anode(NVPF@C@CNTs//HC).Additionally,the electrochemical performance of the full cell at high temperature is also investigated(95.3 mAh g^(-1)after 100 cycles at 1 C at 50℃).Such nanoscale dual-carbon networks engineering and thorough discussion of ion diffusion kinetics might make contributions to accelerating the process of phosphate cathodes in SIBs for large-scale energy storages.展开更多
Rare earth mineral fast ion conductors of Li 1+2 x+3y Al x Sc y Zn y Ti 2- x-2y Si x P 3- x O 12 system based on LiTi 2(PO 4) 3 were prepared by solid phase reaction at hig...Rare earth mineral fast ion conductors of Li 1+2 x+3y Al x Sc y Zn y Ti 2- x-2y Si x P 3- x O 12 system based on LiTi 2(PO 4) 3 were prepared by solid phase reaction at high temperature (1000～1300 ℃) for about 30 h using refined natural kaolinite and Sc 2O 3. The X ray diffraction analysis shows that a Nasicon like structure with R3c space group can be found in the composition range of x =0.1, 0.2, y ≤0.2. The maximum lithium ion conductivity is 1.19×10 -4 S·cm -1 for the composition with x =0.1, y =0.08 at room temperature, and its activation energy is 30.6 kJ·mol -1 in the temperature range of 150～300 ℃. The systems with these compositions have high conductivity of about 10 -2 S·cm -1 at 300 ℃.展开更多
基金financially supported by Science and Technology Foundation of Guizhou Province(QKHZC[2020]2Y037)the Science and Technology Innovation Program of Hunan Province(2020RC4005,2019RS1004)+2 种基金Research start-up funding from Central South University(202044019)Innovation Mover Program of Central South University(2020CX007)National Natural Science Foundation of China(U21A20284)
文摘Sodium-ion batteries(SIBs)have rapidly risen to the forefront of energy storage systems as a promising supplementary for Lithium-ion batteries(LIBs).Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)as a common cathode of SIBs,features the merits of high operating voltage,small volume change and favorable specific energy density.However,it suffers from poor cycling stability and rate performance induced by its low intrinsic conductivity.Herein,we propose an ingenious strategy targeting superior SIBs through cross-linked NVPF with multi-dimensional nanocarbon frameworks composed of amorphous carbon and carbon nanotubes(NVPF@C@CNTs).This rational design ensures favorable particle size for shortened sodium ion transmission pathway as well as improved electronic transfer network,thus leading to enhanced charge transfer kinetics and superior cycling stability.Benefited from this unique structure,significantly improved electrochemical properties are obtained,including high specific capacity(126.9 mAh g^(-1)at 1 C,1 C=128 mA g^(-1))and remarkably improved long-term cycling stability with 93.9%capacity retention after 1000 cycles at 20 C.The energy density of 286.8 Wh kg^(-1)can be reached for full cells with hard carbon as anode(NVPF@C@CNTs//HC).Additionally,the electrochemical performance of the full cell at high temperature is also investigated(95.3 mAh g^(-1)after 100 cycles at 1 C at 50℃).Such nanoscale dual-carbon networks engineering and thorough discussion of ion diffusion kinetics might make contributions to accelerating the process of phosphate cathodes in SIBs for large-scale energy storages.
文摘Rare earth mineral fast ion conductors of Li 1+2 x+3y Al x Sc y Zn y Ti 2- x-2y Si x P 3- x O 12 system based on LiTi 2(PO 4) 3 were prepared by solid phase reaction at high temperature (1000～1300 ℃) for about 30 h using refined natural kaolinite and Sc 2O 3. The X ray diffraction analysis shows that a Nasicon like structure with R3c space group can be found in the composition range of x =0.1, 0.2, y ≤0.2. The maximum lithium ion conductivity is 1.19×10 -4 S·cm -1 for the composition with x =0.1, y =0.08 at room temperature, and its activation energy is 30.6 kJ·mol -1 in the temperature range of 150～300 ℃. The systems with these compositions have high conductivity of about 10 -2 S·cm -1 at 300 ℃.
