The limited lithium reserves and the increasing cost of lithium sources have hampered extensive applications of lithium-ion batteries to large-scale electric energy storage. It is significantly urgent to develop alternative low-cost electric energy storage devices, during which rechargeable sodium-ion batteries (SIBs) have attracted extensive attention due to abundant sodium resources and similar electrochemical properties to lithium-ion batteries. Na3V2(PO4)2F3 (NVPF) is considered as one of the most promising candidates, owing to the merits of super high ionic conductivity, high theoretical specific capacity, good thermal stability and small volume effect. In this work, through hydrothermal process and post calcination, nitrogen-doped carbon-coated NVPF (NVPF@C-N) composites were obtained by adding urea and citric acid during the hydrothermal process. Particularly, nitrogen doping could substantially enhance the pore structure and electrical conductivity of the carbon layer. When used as the SIB cathode, NVPF@C-N exhibited high reversible capacity and excellent rate capability. Under 1 C and 10 C rates, the NVPF@C-N cathode delivered initial discharge capacity of 121 mAh/g and 110 mAh/g, respectively. Even at the rate of 90 C, 66 mAh/g can be obtained. For the cycling stability of NVPF@C-N, the voltage plateau still could be well maintained even after 200 cycles at the rate of 1 C, and the electrode still retained a capacity of 111 mAh/g. Particularly, a retention of 87% was obtained after 1000 cycles at the rate of 10 C, and a retention of 54% was still maintained even after 6000 cycles.
在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15]。在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18]。然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20]。未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用。为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略。值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能。因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用。
Fig. 2
(a) Raman spectra of NVPF@C-N and NVPF@C; (b) BET analysis and pore size distribution of NVPF@C-N and NVPF; The high-resolution XPS spectra of the NVPF@C-N material: (c) C, (d) N
Fig. 4
Electrochemical performance of NVPF@C-N cathode in sodium-ion half-cell. (a) The first four CV curves at a scan rate of 0.1 mV/s between 2.3 V and 4.5 V; (b) The first charge/discharge profiles of NVPF, NVPF@C and NVPF@C-N at 1 C; (c) The rate capacity from 1 C to 90 C of NVPF, NVPF@C and NVPF@C-N; (d) The comparison of rate performance for NVPF cathodes
Fig. 5
(a) Corresponding Ragone plots of NVPF@C-N and NVPF@C; (b) The charge/discharge profiles of the selected cycles at 1 C for NVPF@C-N cathode; (c) The long cycling performance of NVPF@C-N at 10 C
WANG P F, YOU Y, YIN Y X, et al. Layered oxide cathodes for sodium-ion batteries: Phase transition, air stability, and performance[J]. Advanced Energy Materials, 2018, 8(8): doi:10.1002/aenm.201701912.
ETACHERI V, MAROM R, ELAZARI R, et al. Challenges in the development of advanced Li-ion batteries: A review[J]. Energy & Environmental Science, 2011, 4(9): 3243-3262.
ETACHERI V, MAROM R, ELAZARI R, et al. Challenges in the development of advanced Li-ion batteries: A review[J]. Energy & Environmental Science, 2011, 4(9): 3243.
XIAO Y, LEE S H, SUN Y K. The application of metal sulfides in sodium ion batteries[J]. Advanced Energy Materials, 2017, 7(3): doi:10.1002/aenm.201601329.
YANG M, ZHONG Y R, BAO J, et al. Achieving battery-level energy density by constructing aqueous carbonaceous supercapacitors with hierarchical porous N-rich carbon materials[J]. Journal of Materials Chemistry A, 2015, 3(21): 11387-11394.
DE LA LLAVE E, BORGEL V, PARK K J, et al. Comparison between Na-ion and Li-ion cells: Understanding the critical role of the cathodes stability and the anodes pretreatment on the cells behavior[J]. ACS Applied Materials & Interfaces, 2016, 8(3): 1867-1875.
HU Z, ZHU Z Q, CHENG F Y, et al. Pyrite FeS2 for high-rate and long-life rechargeable sodium batteries[J]. Energy & Environmental Science, 2015, 8(4): 1309-1316.
KIM S W, SEO D H, MA X H, et al. Electrode materials for rechargeable sodium-ion batteries: Potential alternatives to current lithium-ion batteries[J]. Advanced Energy Materials, 2012, 2(7): 710-721.
SONG W X, JI X B, WU Z P, et al. First exploration of Na-ion migration pathways in the NASICON structure Na3V2(PO4)3[J]. Journal of Materials Chemistry A, 2014, 2(15): 5358.
WARNER T E, MILIUS W, MAIER J. New copper phosphates with the NASICON or alluaudite-type structures as ionic or mixed conductors[J]. Solid State Ionics, 1994, 74(3/4): 119-123.
GUO J Z, WANG P F, WU X L, et al. High-energy/power and low-temperature cathode for sodium-ion batteries: In situ XRD study and superior full-cell performance[J]. Advanced Materials, 2017, 29(33). doi:10.1002.adma.201701968.
LIU Q, WANG D X, YANG X, et al. Carbon-coated Na3V2(PO4)2F3 nanoparticles embedded in a mesoporous carbon matrix as a potential cathode material for sodium-ion batteries with superior rate capability and long-term cycle life[J]. Journal of Materials Chemistry A, 2015, 3(43): 21478-21485.
BIANCHINI M, FAUTH F, BRISSET N, et al. Comprehensive investigation of the Na3V2(PO4)2F3-NaV2(PO4)2F3 system by operando high resolution synchrotron X-ray diffraction[J]. Chemistry of Materials, 2015, 27(8): 3009-3020.
SERRAS P, PALOMARES V, ALONSO J, et al. Electrochemical Na extraction/insertion of Na3V2O2x(PO4)2F3-2x[J]. Chemistry of Materials, 2013, 25(24): 4917-4925.
YI H M, LING M X, XU W B, et al. VSC-doping and VSU-doping of Na3V2-xTix(PO4)2F3 compounds for sodium ion battery cathodes: Analysis of electrochemical performance and kinetic properties[J]. Nano Energy, 2018, 47: 340-352.
XIANG X D, LU Q Q, HAN M, et al. Superior high-rate capability of Na3(VO0.5)2(PO4)2F2 nanoparticles embedded in porous graphene through the pseudocapacitive effect[J]. Chemical Communications, 2016, 52(18): 3653-3656.
JIN H Y, DONG J, UCHAKER E, et al. Three dimensional architecture of carbon wrapped multilayer Na3V2O2(PO4)2F nanocubes embedded in graphene for improved sodium ion batteries[J]. Journal of Materials Chemistry A, 2015, 3(34): 17563-17568.
WEI T Y, YANG G Z, WANG C X. Bottom-up assembly of strongly-coupled Na3V2(PO4)3/C into hierarchically porous hollow nanospheres for high-rate and-stable Na-ion storage[J]. Nano Energy, 2017, 39: 363-370.
KUMAR P R, JUNG Y H, KIM D K. Influence of carbon polymorphism towards improved sodium storage properties of Na3V2O2x(PO4)2F3-2x[J]. Journal of Solid State Electrochemistry, 2017, 21(1): 223-232.
PARK S, SONG J J, KIM S, et al. Phase-pure Na3V2(PO4)2F3 embedded in carbon matrix through a facile polyol synthesis as a potential cathode for high performance sodium-ion batteries[J]. Nano Research, 2019, 12(4): 911-917.
KUMAR P R, JUNG Y H, WANG J E, et al. Na3V2O2(PO4)2F-MWCNT nanocomposites as a stable and high rate cathode for aqueous and non-aqueous sodium-ion batteries[J]. Journal of Power Sources, 2016, 324: 421-427.
ZHU C B, WU C, CHEN C C, et al. A high power-high energy Na3V2(PO4)2F3 sodium cathode: Investigation of transport parameters, rational design and realization[J]. Chemistry of Materials, 2017, 29(12): 5207-5215.
WANG C, SHEN W, LIU H M. Nitrogen-doped carbon coated Li3V2(PO4)3 derived from a facile in situ fabrication strategy with ultrahigh-rate stable performance for lithium-ion storage[J]. New Journal of Chemistry, 2014, 38(1): 430-436.
SHEN W, WANG C, XU Q J, et al. Nitrogen-doping-induced defects of a carbon coating layer facilitate Na-storage in electrode materials[J]. Advanced Energy Materials, 2015, 5(1): doi:10.1002/aenm.201400982.
NIE P, ZHU Y Y, SHEN L F. From biomolecule to Na3V2(PO4)3/nitrogen-decorated carbon hybrids: Highly reversible cathodes for sodium-ion batteries[J]. Journal of Materials Chemistry A, 2014, 2(43): 18606-18612.
ZHANG C L, LI H S, PING N, et al. Facile synthesis of nitrogen-doped carbon derived from polydopamine-coated Li3V2(PO4)3 as cathode material for lithium-ion batteries[J]. RSC Advances, 2014, 4(73): 38791-38796.
WANG C, WANG F X, LIU Z C, et al. N-doped carbon hollow microspheres for metal-free quasi-solid-state full sodium-ion capacitors[J]. Nano Energy, 2017, 41: 674-680.
ZHANG L L, MA D, LI T, et al. Polydopamine-derived nitrogen-doped carbon-covered Na3V2(PO4)2F3 cathode material for high-performance Na-ion batteries[J]. ACS Applied Materials & Interfaces, 2018, 10(43): 36851-36859.
SHIN W H, JEONG H M, KIM B G, et al. Nitrogen-doped multiwall carbon nanotubes for lithium storage with extremely high capacity[J]. Nano Letters, 2012, 12(5): 2283-2288.
CAI D D, WANG S Q, LIAN P C, et al. Superhigh capacity and rate capability of high-level nitrogen-doped graphene sheets as anode materials for lithium-ion batteries[J]. Electrochimica Acta, 2013, 90: 492-497.
ZHAO J, GAO Y, LIU Q, et al. High rate capability and enhanced cyclability of Na3V2(PO4)2F3 cathode by in situ coating of carbon nanofibers for sodium-ion battery applications[J]. Chemistry, 2018, 24(12): 2913-2919.
DU P, MI K, HU F D, et al. Hierarchical hollow microspheres Na3V2(PO4)2F3C@rGO as high-performance cathode materials for sodium ion batteries[J]. New Journal of Chemistry, 2020, 44(30): 12985-12992.
LI Y S, LIANG X H, ZHONG G B, et al. Fiber-shape Na3V2(PO4)2F3@N-doped carbon as a cathode material with enhanced cycling stability for Na-ion batteries[J]. ACS Applied Materials & Interfaces, 2020, 12(23): 25920-25929.
PI Y Q, GAN Z W, YAN M Y, et al. Insight into pre-sodiation in Na3V2(PO4)2F3/C@ hard carbon full cells for promoting the development of sodium-ion battery[J]. Chemical Engineering Journal, 2021, 413: doi:10.1016/j.cej.1020.127565.
LIANG K, WANG S J, ZHAO H S, et al. A facile strategy for developing uniform hierarchical Na3V2(PO4)2F3@carbonized polyacrylonitrile multi-clustered hollow microspheres for high-energy-density sodium-ion batteries[J]. Chemical Engineering Journal, 2022, 428: doi:10.1016/j.cej.2022.131780.
ZHANG Y, WANG T, TANG Y K, et al. In situ redox reaction induced firmly anchoring of Na3V2(PO4)2F3 on reduced graphene oxide & carbon nanosheets as cathodes for high stable sodium-ion batteries[J]. Journal of Power Sources, 2021, 516: doi:10.1016/j.jPowsour.2021.230515.
LIU Q, MENG X, WEI Z X, et al. Core/double-shell structured Na3V2(PO4)2F3@C nanocomposite as the high power and long lifespan cathode for sodium-ion batteries[J]. ACS Applied Materials & Interfaces, 2016, 8(46): 31709-31715.
PARK Y U, SEO D H, KWON H S, et al. A new high-energy cathode for a Na-ion battery with ultrahigh stability[J]. Journal of the American Chemical Society, 2013, 135(37): 13870-13878.
WU F, ZHU N, BAI Y, et al. Unveil the mechanism of solid electrolyte interphase on Na3V2(PO4)3 formed by a novel NaPF6/BMITFSI ionic liquid electrolyte[J]. Nano Energy, 2018, 51: 524-532.
ZHAO J, YANG X, YAO Y, et al. Moving to aqueous binder: A valid approach to achieving high-rate capability and long-term durability for sodium-ion battery[J]. Advanced Science, 2018, 5(4): doi:10.1002/advs.201700768.
LI L, ZHANG N, SU Y Q, et al. Fluorine dissolution-induced capacity degradation for fluorophosphate-based cathode materials[J]. ACS Applied Materials & Interfaces, 2021, 13(20): 23787-23793.
HWANG J, MATSUMOTO K, HAGIWARA R. Electrolytes toward high-voltage Na3V2(PO4)2F3 positive electrode durable against temperature variation[J]. Advanced Energy Materials, 2020, 10(34): doi:10.1002/aenm.202001880.
ZHOU X, XIE Y, DENG Y F, et al. The enhanced rate performance of LiFe0.5Mn0.5PO4/C cathode material via synergistic strategies of surfactant-assisted solid state method and carbon coating[J]. Journal of Materials Chemistry A, 2015, 3(3): 996-1004.
YANG S L, HU M J, XI L J, et al. Solvothermal synthesis of monodisperse LiFePO4 micro hollow spheres as high performance cathode material for lithium ion batteries[J]. ACS Applied Materials & Interfaces, 2013, 5(18): 8961-8967.
YANG L, LIAO H X, TIAN Y, et al. Rod-like Sb2MoO6: Structure evolution and sodium storage for sodium-ion batteries[J]. Small Methods, 2019, 3(5): doi:10.1002/smtd.201800533.
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
0
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
0
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...
0
0
1
... 在钠离子电池正极材料的研究中,钠超离子导体(NASICON)材料因具有稳定的三维结构以及可保证Na+的快速插入与脱出能力受到研究者的广泛青睐[13-15].在这类电极材料中,Na3V2(PO4)2F3(NVPF)由于PO43-聚阴离子的诱导效应和强的V—F离子键,表现出高的工作电压(3.95 V vs. Na/Na+)和高的理论比容量(128 mAh/g),其理论能量密度高达500 Wh/kg[16-18].然而,与其他聚阴离子型电极材料一样,由于V原子被PO43-四面体隔离,NVPF的电子导电率极低(10-12 S/cm)[19-20].未经修饰的NVPF材料即使在低电流密度下仍然难以获得高比容量,阻碍了该材料的实际应用.为解决这一困境,合理的微/纳结构设计[21-22]以及构筑碳基复合物[23-26]是常用增强电子导电性和电化学性能的有效策略.值得注意的是,由于大的比表面积和高的表面能,NVPF纳米颗粒在复合物中常呈现不均匀分布和严重团聚的现象,导致差的电解液浸润和加剧的界面阻抗,限制了高倍率性能.因此,发展简单有效的NVPF复合正极材料制备方法能够推动高性能钠离子电池的商业化应用. ...