O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on...O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.展开更多
Energy-storage systems and their production have attracted significant interest for practical applications.Batteries are the foundation of sustainable energy sources for electric vehicles(EVs),portable electronic devi...Energy-storage systems and their production have attracted significant interest for practical applications.Batteries are the foundation of sustainable energy sources for electric vehicles(EVs),portable electronic devices(PEDs),etc.In recent decades,Lithium-ion batteries(LIBs) have been extensively utilized in largescale energy storage devices owing to their long cycle life and high energy density.However,the high cost and limited availability of Li are the two main obstacles for LIBs.In this regard,sodium-ion batteries(SIBs) are attractive alternatives to LIBs for large-scale energy storage systems because of the abundance and low cost of sodium materials.Cathode is one of the most important components in the battery,which limits cost and performance of a battery.Among the classified cathode structures,layered structure materials have attracted attention because of their high ionic conductivity,fast diffusion rate,and high specific capacity.Here,we present a comprehensive review of the classification of layered structures and the preparation of layered materials.Furthermore,the review article discusses extensively about the issues of the layered materials,namely(1) electrochemical degradation,(2) irreversible structural changes,and(3) structural instability,and also it provides strategies to overcome the issues such as elemental phase composition,a small amount of elemental doping,structural design,and surface alteration for emerging SIBs.In addition,the article discusses about the recent research development on layered unary,binary,ternary,quaternary,quinary,and senary-based O3-and P2-type cathode materials for high-energy SIBs.This review article provides useful information for the development of high-energy layered sodium transition metal oxide P2 and O3-cathode materials for practical SIBs.展开更多
The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X...The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.展开更多
本文通过固相法制备出NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2-x)F_x(x=0,0.005,0.01,0.02)正极材料.该材料的电化学性能表明F元素的掺杂有利于提高其循环性和稳定性.其中当F元素的掺杂量为0.01时,材料的电化学性能最为优异,在150 mA g^(-1)的...本文通过固相法制备出NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2-x)F_x(x=0,0.005,0.01,0.02)正极材料.该材料的电化学性能表明F元素的掺杂有利于提高其循环性和稳定性.其中当F元素的掺杂量为0.01时,材料的电化学性能最为优异,在150 mA g^(-1)的电流密度下,循环70圈容量仍保持在110 mA hg^(-1).通过XPS、Raman等表征方法研究了F元素掺杂提高材料电化学性能的机理.本工作对于F元素掺杂钠电层状正极材料研究具有一定的参考意义.展开更多
基金financial support from the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. NSFC51621001)the Guangdong Special Support Program (2017TQ04N224)+1 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar (Grant No. 2017B030306004)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme。
文摘O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.
基金supported by a grant from the Subway Fine Dust Reduction Technology Development Project of the Ministry of Land Infrastructure and Transport,Republic of Korea(21QPPWB152306-03)the Basic Science Research Capacity Enhancement Project through a Korea Basic Science Institute(National Research Facilities and Equipment Center)grant funded by the Ministry of Education of the Republic of Korea(2019R1A6C1010016)。
文摘Energy-storage systems and their production have attracted significant interest for practical applications.Batteries are the foundation of sustainable energy sources for electric vehicles(EVs),portable electronic devices(PEDs),etc.In recent decades,Lithium-ion batteries(LIBs) have been extensively utilized in largescale energy storage devices owing to their long cycle life and high energy density.However,the high cost and limited availability of Li are the two main obstacles for LIBs.In this regard,sodium-ion batteries(SIBs) are attractive alternatives to LIBs for large-scale energy storage systems because of the abundance and low cost of sodium materials.Cathode is one of the most important components in the battery,which limits cost and performance of a battery.Among the classified cathode structures,layered structure materials have attracted attention because of their high ionic conductivity,fast diffusion rate,and high specific capacity.Here,we present a comprehensive review of the classification of layered structures and the preparation of layered materials.Furthermore,the review article discusses extensively about the issues of the layered materials,namely(1) electrochemical degradation,(2) irreversible structural changes,and(3) structural instability,and also it provides strategies to overcome the issues such as elemental phase composition,a small amount of elemental doping,structural design,and surface alteration for emerging SIBs.In addition,the article discusses about the recent research development on layered unary,binary,ternary,quaternary,quinary,and senary-based O3-and P2-type cathode materials for high-energy SIBs.This review article provides useful information for the development of high-energy layered sodium transition metal oxide P2 and O3-cathode materials for practical SIBs.
基金financially supported by (i) Suranaree University of Technology,(ii) Thailand Science Research and Innovation,and (iii) National Science,Research and Innovation Fund(project codes 90464 and 160363)。
文摘The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.
基金supported by the National High-Tech R&D Program of China (2015AA034601, 2016YFB010030X, and 2016YFB0700600)the State Key Laboratory of Materials Processing and Die & Mould Technologythe Analytical and Testing Center of Huazhong University of Science Technology
文摘本文通过固相法制备出NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2-x)F_x(x=0,0.005,0.01,0.02)正极材料.该材料的电化学性能表明F元素的掺杂有利于提高其循环性和稳定性.其中当F元素的掺杂量为0.01时,材料的电化学性能最为优异,在150 mA g^(-1)的电流密度下,循环70圈容量仍保持在110 mA hg^(-1).通过XPS、Raman等表征方法研究了F元素掺杂提高材料电化学性能的机理.本工作对于F元素掺杂钠电层状正极材料研究具有一定的参考意义.
