Nanoflake‐Assembled Hierarchical Na3V2(PO4)3/C Microflowers: Superior Li Storage Performance and Insertion/Extraction Mechanism

An, Qinyou; Xiong, Fangyu; Wei, Qiulong; Sheng, Jinzhi; He, Liang; Ma, Dongling; Yao, Yan; Mai, Liqiang

doi:10.1002/aenm.201401963

Cited by 175 publications

(162 citation statements)

References 51 publications

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“…[1][2][3][4][5][6][7] The reversible extraction of sodium occurs as a two-phase reaction at 3.37 V vs. Na + /Na (V 3+ oxidized to V 4+ ) for a theoretical gravimetric capacity of 117.6 mA h g À1 yielding an energy density of 396 W h kg À1 . [1][2][3][4][5][6][7] Gopalakrishnan 9 was the rst to report on the chemical oxidation of NASICON Na 3 V III 2 (PO 4 ) 3 (Na + extraction) to yield a new Na-free mixed-valence V V V IV (PO 4 ) 3 composition, suggesting the theoretical extraction of 3 Na + per 2 vanadium (i.e. Since then, several high-prole studies have been conducted in order to obtain optimized performances.…”

Section: Introductionmentioning

confidence: 99%

Improving the energy density of Na₃V₂(PO₄)₃-based positive electrodes through V/Al substitution

et al. 2015

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The crystal chemistry and the electrochemical properties upon Na + extraction/insertion of NASICON-type Na 3 Al y V 2Ày (PO 4 ) 3 compositions (y ¼ 0.1, 0.25 and 0.5) were investigated. It was found that this family of V/Al substituted NASICON materials undergoes multiple reversible phase transitions between À50 C and 250 C upon heating, from monoclinic to rhombohedral symmetry, related to progressive disordering of Na + ions within the framework. Na + insertion/extraction mechanisms were monitored by operando X-ray diffraction. It is shown for the first time that substitution of aluminum for vanadium in Na 3 Al 0.5 V 1.5 (PO 4 ) 3 increases significantly the theoretical energy density of these promising positive electrodes (425 W h kg À1 ) due to its lighter molecular weight and the possibility of reversible operation on the V 4+ /V 5+ redox couple at 3.95 V vs. Na + /Na.

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Section: Introductionmentioning

confidence: 99%

Improving the energy density of Na₃V₂(PO₄)₃-based positive electrodes through V/Al substitution

et al. 2015

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“…Figure 2 a shows the schematic crystal structure of Na 7 V 3 (P 2 O 7 ) 4 based on the refi ned information from the XRD pattern. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] However, the generally low redox potential of Na + /Na (−2.71 V vs standard hydrogen electrode (SHE)) compared with that of Li + /Li (−3.04 V vs SHE) reduces the operating voltage of NIBs, leading to a low energy density. Figure 2 b shows the arrangement of VO 6 and P 2 O 7 groups in quasi-layers 1 and 2.…”

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confidence: 99%

“…[1][2][3][4] Although Li-ion batteries (LIBs) are considered promising candidates for large-scale energy storage applications because of their high energy and power densities, there are growing concerns about the availability of secure Li resources to satisfy the rapidly rising global demands for LIBs. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] However, the generally low redox potential of Na + /Na (−2.71 V vs standard hydrogen electrode (SHE)) compared with that of Li + /Li (−3.04 V vs SHE) reduces the operating voltage of NIBs, leading to a low energy density. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] However, the generally low redox potential of Na + /Na (−2.71 V vs standard hydrogen electrode (SHE)) compared with that of Li + /Li (−3.04 V vs SHE) reduces the operating voltage of NIBs, leading to a low energy density.…”

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confidence: 99%

Tailoring a New 4V‐Class Cathode Material for Na‐Ion Batteries

Kim

Park

Kim

et al. 2016

Advanced Energy Materials

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8C, retaining 84% of its initial capacity in its micrometer-sized particle morphology. Na 7 V 3 (P 2 O 7 ) 4 was successfully synthesized for the fi rst time using the Na-phosphate fl ux method (see the Experimental Section in Supporting Information for details). Note that excess amount of Na-phosphate were used and then washed with water. [ 27 ] The structural characterization based on Rietveld refi nement of X-ray diffraction (XRD) in Figure 1 a reveals that Na 7 V 3 (P 2 O 7 ) 4 has the C2/ c space group with a = 9.7219(4) Å, b = 8.3185(4) Å, c = 27.6051(11) Å, and β = 86.724(4)°, which is isostructural with the previously known Na 7 Fe 3 (P 2 O 7 ) 4 . [ 27 ] No contamination or second phases are detected in the XRD pattern. Additionally, through the XRD measurement in the air, it is also identifi ed that this material is stable in the air or humid condition without any structural changes or phase separation, unlike most of Na x MO 2 [M = Fe, Mn, Co, Ni, etc.]. [ 28 ] The detailed structure information is summarized in Table T1 (Supporting Information), showing the low structural R -factors ( R p = 7.69%, R I = 7.99%, R F = 7.06%, χ 2 = 8.14%). The morphology of the Na 7 V 3 (P 2 O 7 ) 4 sample was examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM), revealing a primary particle size of a few micrometers (inset of Figure 1 and Supporting Information, Figure S1). Figure 2 a shows the schematic crystal structure of Na 7 V 3 (P 2 O 7 ) 4 based on the refi ned information from the XRD pattern. The structure consists of a succession of two layers, where quasi-layer 1 consists of infi nite chains of V(1)[P(1)P(2)O 7 ] 2 , and quasi-layer 2 consists of those of [V(2)P(3)P(4)O 7 ] 2 . Figure 2 b shows the arrangement of VO 6 and P 2 O 7 groups in quasi-layers 1 and 2. This connection of VO 6 and P 2 O 7 creates large tunnels, which serve as 3D Na diffusion paths in the structure. The Na(2), Na(3), and Na(4) sites are interconnected in quasi-layer 1, and each Na (2) and Na(4) ion in quasi-layer 1 is connected with Na(1) ions in quasi-layer 2. A notable feature of the crystal structure is that VO 6 octahedra in Na 7 V 3 (P 2 O 7 ) 4 share every corner with P 2 O 7 , which is rather unique among vanadium-based polyanion compounds. [ 6,8,11,13,19 ] Because the redox potential is signifi cantly affected by the interaction between the transition metal and polyanions and generally increases via the inductive effect, it is expected that Na 7 V 3 (P 2 O 7 ) 4 may exhibit a higher redox potential than other vanadium-based cathode materials.To investigate the de/sodiation mechanism and theoretical redox potential, fi rst-principles calculations of Na 7 V 3 (P 2 O 7 ) 4 were performed considering the extraction of Na ions from symmetrically different Na sites. The Na2, Na3, and Na4 sites were observed to have similar site energies of approximately 3.8 eV; however, that of the Na1 site in quasi-layer 2 was approximately 1 eV higher than those of the other sites (≈4.9 eV) ( Table T2, Suppor...

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“…The nanoscaled subunits provide shorter lithium diffusion distance and larger contact area between electrode and electrolyte, and the self-assembled hierarchical microstructures improve the energy packing density2930. Therefore, constructing carbon and active material hierarchical structures is believed a promising way to achieve good electrochemical performance and desired energy density313233.…”

mentioning

confidence: 99%

Carbon wrapped hierarchical Li3V2(PO4)3 microspheres for high performance lithium ion batteries

Liang

Tan

Xiong

et al. 2016

Sci Rep

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Nanomaterials are extensively studied in electrochemical energy storage and conversion systems because of their structural advantages. However, their volumetric energy density still needs improvement due to the high surface area, especially the carbon based nanocomposites. Constructing hierarchical micro-scaled materials from closely stacked subunits is proposed as an effective way to solve the problem. In this work, Li3V2(PO4)3@carbon hierarchical microspheres are prepared by a solvothermal reaction and subsequent annealing. Hierarchical Li3V2(PO4)3 structures with different subunits are obtained with the aid of polyvinyl pyrrolidone (PVP). Moreover, excessive PVP interconnect and form PVP-based hydrogels, which later convert into conductive carbon layer on the surface of Li3V2(PO4)3 microspheres during the annealing process. As a cathode material for lithium ion batteries, the 3D carbon wrapped Li3V2(PO4)3 hierarchical microspheres exhibit high rate capability and excellent cycling stability. The electrode has the capacity retention of 80% after 5000 cycles even at 50C.

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Nanoflake‐Assembled Hierarchical Na₃V₂(PO₄)₃/C Microflowers: Superior Li Storage Performance and Insertion/Extraction Mechanism

Cited by 175 publications

References 51 publications

Improving the energy density of Na₃V₂(PO₄)₃-based positive electrodes through V/Al substitution

Improving the energy density of Na₃V₂(PO₄)₃-based positive electrodes through V/Al substitution

Tailoring a New 4V‐Class Cathode Material for Na‐Ion Batteries

Carbon wrapped hierarchical Li3V2(PO4)3 microspheres for high performance lithium ion batteries

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Nanoflake‐Assembled Hierarchical Na3V2(PO4)3/C Microflowers: Superior Li Storage Performance and Insertion/Extraction Mechanism

Cited by 175 publications

References 51 publications

Improving the energy density of Na3V2(PO4)3-based positive electrodes through V/Al substitution

Improving the energy density of Na3V2(PO4)3-based positive electrodes through V/Al substitution

Tailoring a New 4V‐Class Cathode Material for Na‐Ion Batteries

Carbon wrapped hierarchical Li3V2(PO4)3 microspheres for high performance lithium ion batteries

Contact Info

Product

Resources

About

Nanoflake‐Assembled Hierarchical Na₃V₂(PO₄)₃/C Microflowers: Superior Li Storage Performance and Insertion/Extraction Mechanism

Improving the energy density of Na₃V₂(PO₄)₃-based positive electrodes through V/Al substitution

Improving the energy density of Na₃V₂(PO₄)₃-based positive electrodes through V/Al substitution