Corresponding Author

Kai Wu(WuK@catlbattery.com)


High-temperature solid-state method, hydro-thermal method and solvo-thermal method have been mainly employed to synthesize Na3V2(PO4)2O2F (NVPF) cathode materials. However, these methods are energy consuming and complicated, which is not applicable for a large scale industrial production. In this study, a rather low-temperature (70℃) co-precipitation strategy was proposed to synthesize NVPF cathode materials. The as-prepared NVPF cathode materials showed a spherical shape with a diameter of 400 ~ 500 nm, and exhibited a sodium storage of 105.6 mAh·g-1 and an efficiency of 90.06%. After a simple thermal process, the specific capacity of the material increased to 124.3 mAh·g-1, and the first cycle efficiency increased to 96.06%. More specifically, a series of experiments with different heat temperatures were done and the results revealed that the best electrochemical performance of NVPF cathode material was achieved with the heat treatment of 600℃ for 2 h under argon atmosphere. Techniques including XRD, SEM, FT-IR, TG-MS, and carbon content analysis and Rietveld analysis were used in order to figure out the effect of the thermal process. The results revealed that the heat treatment could remove the crystal water that led to many side reactions and lowered the cycle efficiency, remove the adsorbed hydroxyl resulted from liquid-phase synthesis, as well as increase the crystallinity of NVPF cathode materials and coated a tinny amount of carbon on the surface of the materials through the decomposition of the remained C2O42-, thus, improving the electrochemical performance of the NVPF cathode materials. Additionally, a full cell with a capacity of 24 mAh composed of a NVPF cathode and a commercial hard carbon anode was fabricated and tested. The cell exhibited an excellent cycle and rate performance. It remained 94.6% of its initial capacity after 1200 cycles at 1 C and 86% of the reference rate (0.33 C) capacity even at 4 C. Furthermore, this method is attractive to the large-scale industrial production of NVPF cathode materials.

Graphical Abstract


Na3V2(PO4)2O2F, NVPF, co-precipitation, electrochemical performance, sodium ion battery

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[1] Yabuuchi N, Kubota K, Dahbi M, Komaba S. Research development on sodium-ion batteries[J]. Chem. Rev., 2014,114(23):11636-11682.
doi: 10.1021/cr500192f URL pmid: 25390643

[2] Liu Y C(刘永畅), Chen C C(陈程成), Zhang N(张宁), Wang L B(王刘彬), Xiang X D(向兴德), Chen J(陈军). Research and application of key materials for sodium-ion batteries[J]. J. Electrochem. (电化学), 2016,22(5):437-452.

[3] Hwang J Y, Myung S T, Sun Y K. Sodium-ion batteries: present and future[J]. Chem. Soc. Rev., 2017,46(12):3529-3614.
doi: 10.1039/c6cs00776g URL pmid: 28349134

[4] Delmas C. Sodium and sodium-ion batteries: 50 years of research[J]. Adv. Energy Mater., 2018,8(17):1703137.
doi: 10.1002/aenm.v8.17 URL

[5] Deng J, Luo W B, Chou S L, Liu H K, Dou S X. Sodium-ion batteries: From academic research to practical commercialization[J]. Adv. Energy Mater., 2018,8(4):1701428.
doi: 10.1002/aenm.201701428 URL

[6] Chen L, Fiore M, Wang J E, Ruffo R, Kim D K, Longoni G. Readiness level of sodium-ion battery technology: A materials review[J]. Adv. Sustain. Syst., 2018,2(3):1700153.
doi: 10.1002/adsu.v2.3 URL

[7] Xu G L, Amine R, Abouimrane A, Che H Y, Dahbi M, Ma Z F, Saadoune I, Alami J, Mattis W L, Pan F, Chen Z H, Amine K. Challenges in developing electrodes, electrolytes, and diagnostics tools to understand and advance sodium-ion batteries[J]. Adv. Energy Mater., 2018,8(14):1702403.
doi: 10.1002/aenm.201702403 URL

[8] Kumar P R, Jung Y H, Kim D K. Influence of carbon polymorphism towards improved sodium storage properties of Na3V2O2x(PO4)2F3-2x[J]. J. Solid State Electrochem., 2017,21(1):223-232.
doi: 10.1007/s10008-016-3365-6 URL

[9] Guo J Z, Wang P F, Wu X L, Zhang X H, Yan Q Y, Chen H, Zhang J P, Guo Y G. High-energy/power and low-temperature cathode for sodium-ion batteries: in situ XRD study and superior full-cell performance[J]. Adv. Mater., 2017,29(33):1701968.
doi: 10.1002/adma.v29.33 URL

[10] Park Y U, Seo D H, Kim H, Kim J, Lee S, Kim B, Kang K. A family of high-performance cathode materials for Na-ion batteries, Na3(VO1-xPO4)2F1+2x(0≤x≤1): Combined first-principles and experimental study[J]. Adv. Funct. Mater., 2014,24(29):4603-4614.
doi: 10.1002/adfm.201400561 URL

[11] Park Y U, Seo D H, Kim B, Hong K P, Kim H, Lee S, Shakoor R A, Miyasaka K, Tarascon J M, Kang K. Tailoring a fluorophosphate as a novel 4 V cathode for lithium-ion batteries[J]. Sci. Rep., 2012,2:704.
doi: 10.1038/srep00704 URL pmid: 23050088

[12] Serras P, Palomares V, Kubiak P, Lezama L, Rojo T. Enhanced electrochemical performance of vanadyl (IV) Na3(VO)2(PO4)2F by ex-situ carbon coating[J]. Electro-chem. Commun., 2013,34:344-347.

[13] Sharma N, Serras P, Palomares V, Brand H E A, Alonso J, Kubiak P, Luisa Fdez-Gubieda M, Rojo T. Sodium distribution and reaction mechanisms of a Na3V2O2(PO4)2F electrode during use in a sodium-ion battery[J]. Chem. Mater., 2014,26(11):3391-3402.
doi: 10.1021/cm5005104 URL

[14] Jin H Y, Dong J, Uchaker E, Zhang Q F, Zhou X Z, Hou S E, Li J Y, Cao G Z. Three dimensional architecture of carbon wrapped multilayer Na3V2O2(PO4)2F nanocubesembedded in graphene for improved sodium ion batteries[J]. J. Mater. Chem. A, 2015,3(34):17563-17568.
doi: 10.1039/C5TA03164H URL

[15] Deng G, Chao D L, Guo Y W, Chen Z, Wang H H, Savilov S V, Lin J Y, Shen Z X. Graphene quantum dots-shielded Na3(VO)2(PO4)2F@C nanocuboids as robust cathode for Na-ion battery[J]. Energy Storage Mater., 2016,5:198-204.

[16] Peng M H, Zhang D T, Zheng L M, Wang X Y, Lin Y, Xia D G, Sun Y G, Guo G S. Hierarchical Ru-doped sodium vanadium fluorophosphates hollow microspheres as a cathode of enhanced superior rate capability and ultralong stability for sodium-ion batteries[J]. Nano energy, 2017,31:64-73.
doi: 10.1016/j.nanoen.2016.11.023 URL

[17] Xu M W, Wang L, Zhao X, Song J, Xie H, Lu Y H, Goodenough J B. Na3V2O2(PO4)2F/graphene sandwich structure for high-performance cathode of a sodium-ion battery[J]. Phys. Chem. Chem. Phys., 2013,15(31):13032-13037.
URL pmid: 23817591

[18] Xu M W, Xiao P H, Stauffer S, Song J, Henkelman G, Goodenough J B. Theoretical and experimental study of vanadium-based fluorophosphate cathodes for rechargeable batteries[J]. Chem. Mater., 2014,26(10):3089-3097.
doi: 10.1021/cm500106w URL

[19] Rudola A, Aurbach D, Balaya P. A new phenomenon in sodium batteries: Voltage step due to solvent interaction[J]. Electrochem. Commun., 2014,46:56-59.
doi: 10.1016/j.elecom.2014.06.008 URL



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