Benefitting from its unique NASICON-type framework,the Na_(3)V_(2)(PO_(4))_(3)(NVP)cathodes have aroused extensive interest and have been deemed as the promising cathode candidate for sodium-ion batteries(SIBs).Unfort...Benefitting from its unique NASICON-type framework,the Na_(3)V_(2)(PO_(4))_(3)(NVP)cathodes have aroused extensive interest and have been deemed as the promising cathode candidate for sodium-ion batteries(SIBs).Unfortunately,the poor electronic conductivity,combined with the undesirable volume variations,seriously hinders the practical application of NVP cathode,especially at low temperatures.Herein,a dual-strategy,F substitution accompanied by V vacancies and the construction of three-dimensional(3D)nitrogen-doped carbonaceous frameworks(NC),were employed for the NVP cathode(F-NVP/C@3DNC).The former can remarkably decrease the particle size and enhance Na^(+)migration capability,increasing the ionic conductivity.Meanwhile,the electronic connection and effective buffering can be obtained from the latter,strengthening the electrode integrity.Consequently,up to 100 cycles at 0.1 A g^(-1),a reversible capacity of 113.8 mAh g^(-1),approaching the theoretical value(117 mAh g^(-1)),is demonstrated,accompa-nied by impressive capacity retentions at 1.0(93.75%after 4800 cycles)and 20.0 A g^(-1)(92.7%after 1000 cycles).More importantly,even at-20℃,a superior specific capacity(102.6 mAh g^(-1) after 100 cycles at 0.1 A g^(-1))and high capacity retention(86.6%at 20.0 A g^(-1) up to 1000 cycles)can still be obtained simul-taneously.Significantly,the design of F-NVP/C@3DNC provides insights for the fabrication of polyanion cathodes for applications at low temperatures with modified structure stability and reaction kinetics.展开更多
Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_(3)(VOPO_(4))_(2)F...Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_(3)(VOPO_(4))_(2)F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothe rmal method for the first time.The cathode is able to exhibit superior rate capability and stable cycling performa nce up to 1000 cycles,due to the surface-assembling of crystalline nanocubes on carbon fibers.In addition,it shows good mechanical flexibility,nearly no capacity decay is observed after continuous bending of 500 times.With this novel cathode and a directly-grown Na_(2)Ti_(2)O_(5) anode,a fully binde r-free Na-ion battery is assembled.It can deliver a high wo rking voltage and increased gravimetric energy/power densities(maximum values:220.2 Wh/kg;5674,7 W/kg),and can power a LED indicator at bending angles fro m 0° to 180°.展开更多
Na_(3)(VO)_(2)(PO_(4))_(2)F(NVPOF)has been considered as one potential candidate for sodium-ion batteries because of its high operating voltage and theoretical capacity.However,the poor intrinsic electronic conductivi...Na_(3)(VO)_(2)(PO_(4))_(2)F(NVPOF)has been considered as one potential candidate for sodium-ion batteries because of its high operating voltage and theoretical capacity.However,the poor intrinsic electronic conductivity significantly restricts its widespread application.In response to this drawback,we adopt the optimization strategy of tuning the morphology and structure to boost the electrical conductivity and mitigate the capacity fading.In this paper,NVPOF microspheres with unique porous yolk-shell structure were fabricated via a facile one-step solvothermal method for the first time.By monitoring the morphological evolution with time-dependent experiments,the self-sacrifice and Ostwald ripening mechanism from rough spheres to yolk-shell structure was revealed.Benefited from the favorable interwoven nanosheets shell,inner cavity and porous core structure,the resulting NVPOF electrode exhibits superior rate capability of 63 m A h g^(-1)at 20 C as well as outstanding long-cycling performance with the capacity retention up to 92.1%over 1000 cycles at 5 C.展开更多
Flexible power sources featuring high-performance,prominent flexibility and raised safety have received mounting attention in the area of wearable electronic devices.However,many great challenges remain to be overcome...Flexible power sources featuring high-performance,prominent flexibility and raised safety have received mounting attention in the area of wearable electronic devices.However,many great challenges remain to be overcome,notably the design and fabrication of flexible electrodes with excellent electrochemical performance and matching them with safe and reliable electrolytes.Herein,a facile approach for preparing flexible electrodes,which employs carbon cloth derived from commercial cotton cloth as the substrate of cathode and a flexible anode,is proposed and investigated.The promising cathode(NVPOF@FCC)with high conductivity and outstanding flexibility is prepared by efficiently coating Na_(3)V_(2)(PO_(4))_(2)O_(2)F(NVPOF)on flexible carbon cloth(FCC),which exhibits remarkable electrochemical performance and the significantly improved reaction kinetics.More importantly,a novel flexible quasi-solid-state sodium-ion full battery(QSFB)is feasibly assembled by sandwiching a P(VDF-HFP)-NaClO_(4) gel-polymer electrolyte film between the advanced NVPOF@FCC cathode and FCC anode.And the QSFBs are further evaluated in flexible pouch cells,which not only demonstrates excellent energy-storage performance in aspect of great cycling stability and high-rate capability,but also impressive flexibility and safety.This work offers a feasible and effective strategy for the design of flexible electrodes,paving the way for the progression of practical and sustainable flexible batteries.展开更多
柔性钠离子电池(SIBs)在便携式和可穿戴设备中具有巨大的应用潜力,因为它们在特定情况下具有适用性和价格优势.在正极材料中,磷酸盐电极材料具有结构稳定性好、工作电位高和寿命长的优点.然而,由于对制造要求苛刻,反应复杂,以及柔性基...柔性钠离子电池(SIBs)在便携式和可穿戴设备中具有巨大的应用潜力,因为它们在特定情况下具有适用性和价格优势.在正极材料中,磷酸盐电极材料具有结构稳定性好、工作电位高和寿命长的优点.然而,由于对制造要求苛刻,反应复杂,以及柔性基材的缺失等问题,柔性磷酸盐电极材料的设计仍然是一个巨大的挑战.在此,我们报道了在柔性多孔碳纳米纤维上垂直生长的VO_(2)纳米片原位转化为三维氟磷酸钒钠纳米棒阵列(PCNF@NVOPF NR).PCNF@NVOPF NR实现了兼具柔性与高压正极电极的特点,并具有长期循环稳定性(4500次循环后容量保持率为87.6%).阵列结构可以确保快速的钠反应动力学和低界面电阻.此外,PCNF@NVOPF NR//PCNF@VO_(2)NS@C钠离子全电池表现出高能量和功率密度(220.5 W h kg^(-1)和9400 W kg^(-1)).这种用于柔性正极的材料设计策略可促进实用钠离子电池的商业化.展开更多
基金support from the faculty startup funds from the Yangzhou University,the Natural Science Foundation of Jiangsu Province (Grant No.BK20210821)the National Natural Science Foundation of China (Grant No.21978251)the Lvyangjinfeng Talent Program of Yangzhou.
文摘Benefitting from its unique NASICON-type framework,the Na_(3)V_(2)(PO_(4))_(3)(NVP)cathodes have aroused extensive interest and have been deemed as the promising cathode candidate for sodium-ion batteries(SIBs).Unfortunately,the poor electronic conductivity,combined with the undesirable volume variations,seriously hinders the practical application of NVP cathode,especially at low temperatures.Herein,a dual-strategy,F substitution accompanied by V vacancies and the construction of three-dimensional(3D)nitrogen-doped carbonaceous frameworks(NC),were employed for the NVP cathode(F-NVP/C@3DNC).The former can remarkably decrease the particle size and enhance Na^(+)migration capability,increasing the ionic conductivity.Meanwhile,the electronic connection and effective buffering can be obtained from the latter,strengthening the electrode integrity.Consequently,up to 100 cycles at 0.1 A g^(-1),a reversible capacity of 113.8 mAh g^(-1),approaching the theoretical value(117 mAh g^(-1)),is demonstrated,accompa-nied by impressive capacity retentions at 1.0(93.75%after 4800 cycles)and 20.0 A g^(-1)(92.7%after 1000 cycles).More importantly,even at-20℃,a superior specific capacity(102.6 mAh g^(-1) after 100 cycles at 0.1 A g^(-1))and high capacity retention(86.6%at 20.0 A g^(-1) up to 1000 cycles)can still be obtained simul-taneously.Significantly,the design of F-NVP/C@3DNC provides insights for the fabrication of polyanion cathodes for applications at low temperatures with modified structure stability and reaction kinetics.
基金supported by the National Natural Science Foundation of China (Nos.51972257,51672205 and 21673169)the National Key R&D Program of China (No.2016YFA0202602)。
文摘Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_(3)(VOPO_(4))_(2)F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothe rmal method for the first time.The cathode is able to exhibit superior rate capability and stable cycling performa nce up to 1000 cycles,due to the surface-assembling of crystalline nanocubes on carbon fibers.In addition,it shows good mechanical flexibility,nearly no capacity decay is observed after continuous bending of 500 times.With this novel cathode and a directly-grown Na_(2)Ti_(2)O_(5) anode,a fully binde r-free Na-ion battery is assembled.It can deliver a high wo rking voltage and increased gravimetric energy/power densities(maximum values:220.2 Wh/kg;5674,7 W/kg),and can power a LED indicator at bending angles fro m 0° to 180°.
基金financially supported by the National Natural Science Foundation of China(No.51972259)the Hubei Provincial Natural Science Foundation of China(No.2019CFB519)+1 种基金the Fundamental Research Funds for the Central Universities(No.WUT:2020Ⅲ015GX)the National innovation and entrepreneurship training program for Undergraduate(No.201910497011)。
文摘Na_(3)(VO)_(2)(PO_(4))_(2)F(NVPOF)has been considered as one potential candidate for sodium-ion batteries because of its high operating voltage and theoretical capacity.However,the poor intrinsic electronic conductivity significantly restricts its widespread application.In response to this drawback,we adopt the optimization strategy of tuning the morphology and structure to boost the electrical conductivity and mitigate the capacity fading.In this paper,NVPOF microspheres with unique porous yolk-shell structure were fabricated via a facile one-step solvothermal method for the first time.By monitoring the morphological evolution with time-dependent experiments,the self-sacrifice and Ostwald ripening mechanism from rough spheres to yolk-shell structure was revealed.Benefited from the favorable interwoven nanosheets shell,inner cavity and porous core structure,the resulting NVPOF electrode exhibits superior rate capability of 63 m A h g^(-1)at 20 C as well as outstanding long-cycling performance with the capacity retention up to 92.1%over 1000 cycles at 5 C.
基金supported by the National Natural Science Foundation of China(No.91963118)Science Technology Program of Jilin Province(No.20200201066JC)+2 种基金Fundamental Research Funds for the Central Universities(No.2412020QD013)China Postdoctoral Science Foundation(No.2019M661187)the National Postdoctoral Program for Innovative Talents(BX20190064).
文摘Flexible power sources featuring high-performance,prominent flexibility and raised safety have received mounting attention in the area of wearable electronic devices.However,many great challenges remain to be overcome,notably the design and fabrication of flexible electrodes with excellent electrochemical performance and matching them with safe and reliable electrolytes.Herein,a facile approach for preparing flexible electrodes,which employs carbon cloth derived from commercial cotton cloth as the substrate of cathode and a flexible anode,is proposed and investigated.The promising cathode(NVPOF@FCC)with high conductivity and outstanding flexibility is prepared by efficiently coating Na_(3)V_(2)(PO_(4))_(2)O_(2)F(NVPOF)on flexible carbon cloth(FCC),which exhibits remarkable electrochemical performance and the significantly improved reaction kinetics.More importantly,a novel flexible quasi-solid-state sodium-ion full battery(QSFB)is feasibly assembled by sandwiching a P(VDF-HFP)-NaClO_(4) gel-polymer electrolyte film between the advanced NVPOF@FCC cathode and FCC anode.And the QSFBs are further evaluated in flexible pouch cells,which not only demonstrates excellent energy-storage performance in aspect of great cycling stability and high-rate capability,but also impressive flexibility and safety.This work offers a feasible and effective strategy for the design of flexible electrodes,paving the way for the progression of practical and sustainable flexible batteries.
基金supported by the National Natural Science Foundation of China(51874362 and 22209208)。
文摘柔性钠离子电池(SIBs)在便携式和可穿戴设备中具有巨大的应用潜力,因为它们在特定情况下具有适用性和价格优势.在正极材料中,磷酸盐电极材料具有结构稳定性好、工作电位高和寿命长的优点.然而,由于对制造要求苛刻,反应复杂,以及柔性基材的缺失等问题,柔性磷酸盐电极材料的设计仍然是一个巨大的挑战.在此,我们报道了在柔性多孔碳纳米纤维上垂直生长的VO_(2)纳米片原位转化为三维氟磷酸钒钠纳米棒阵列(PCNF@NVOPF NR).PCNF@NVOPF NR实现了兼具柔性与高压正极电极的特点,并具有长期循环稳定性(4500次循环后容量保持率为87.6%).阵列结构可以确保快速的钠反应动力学和低界面电阻.此外,PCNF@NVOPF NR//PCNF@VO_(2)NS@C钠离子全电池表现出高能量和功率密度(220.5 W h kg^(-1)和9400 W kg^(-1)).这种用于柔性正极的材料设计策略可促进实用钠离子电池的商业化.
