A New Vanadium Dioxide Cathode

Chirayil, Thomas; Zavalij, Peter Y.; Whittingham, M. Stanley

doi:10.1149/1.1837083

Cited by 56 publications

(28 citation statements)

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“…MO 2 structures based entirely on [MO 5 ] polyhedra are very rare. We are aware only of a vanadium dioxide polymorph, VO 2 (C), which is a layered compound composed of sheets of [VO 5 ] square pyramids [78,79], although full crystallographic data has not been published, possibly due to nonstoichiometry and the retention of Li or H 2 O from the synthesis route.…”

Section: F Tio 2 Polymorphs With Low Ti-o Coordinationmentioning

confidence: 99%

Structure of molten titanium dioxide

et al. 2014

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The x-ray structure factor of molten TiO 2 has been measured for the first time, enabled by the use of aerodynamic levitation and laser beam heating, to a temperature of T = 2250(30) K. Ti-O coordination number in the melt is close to n TiO = 5.0(2), with modal Ti-O bond length r TiO = 1.881(5) Å, both values being significantly smaller than for the high temperature stable Rutile crystal structure (n TiO = 6.0, r TiO = 1.959 Å). The structural differences between melt and crystal are qualitatively similar to those for alumina, which is rationalized in terms of the similar field strengths of Ti 4+ and Al 3+. The diffraction data are used to generate physically and chemically reasonable structural models, which are then compared to the predictions based on various classical molecular dynamics (MD) potentials. New interatomic potentials, suitable for modelling molten TiO 2 , are introduced, given the inability of existing MD models to reproduce the diffraction data. These new potentials have the additional great advantage of being able to predict the density and thermal expansion of the melt, as well as solid amorphous TiO 2 , in agreement with published results. This is of critical importance given the strong correlation between density and structural parameters such as n TiO . The large thermal expansion of the melt is associated with weakly temperature dependent structural changes, whereby simulations show that n TiO = 5.85(2) -(3.0(1) x 10 -4 )T (K, 2.75 Å cut-off). The TiO 2 liquid is structurally analogous to the geophysically relevant high pressure liquid silica system at around 27 GPa. We argue that the predominance of 5-fold polyhedra in the melt implies the existence of as yet undiscovered TiO 2 polymorphs, based on lowerthan-octahedral coordination numbers, which are likely to be metastable under ambient conditions. Given the industrial importance of titanium oxides, experimental and computational searches for such polymorphs are well warranted.

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Section: F Tio 2 Polymorphs With Low Ti-o Coordinationmentioning

confidence: 99%

Structure of molten titanium dioxide

et al. 2014

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“…VO 2 (B) has been emerged as another good option as cathode material for lithium ion batteries since 1996. 98 Its structure is built up by distorted octahedral VO 6 that shares both corners and edges, where lithium ions can occupy both octahedral and tetrahedral sites. Commonly, VO 2 (B) is obtained from the reduction of potassium vanadate (K 3 VO 4 ) using potassium borohydride in aqueous media.…”

Section: Vanadium Oxidesmentioning

confidence: 99%

Cathodes for lithium ion batteries: the benefits of using nanostructured materials

Camilo¹,

Torresi²

2006

J. Braz. Chem. Soc.

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As celas de íon lítio disponíveis comercialmente, as quais são as mais avançadas entre as baterias recarregáveis disponíveis até agora, empregam óxidos de metais de transição microcristalinos como catodos, os quais funcionam como matrizes de inserção de lítio. Em busca por uma melhor performance eletroquímica, o uso de nanomateriais no lugar dos materiais convencionais tem emergido como excelente alternativa. Nesta revisão nós apresentaremos uma breve introdução sobre as motivações de usar materiais nanoestruturados como catodos em baterias de íon-lítio. Para ilustrar tais vantagens apresentamos exemplos de pesquisas relacionadas com a preparação e dados eletroquímicos dos mais usados catodos em nanoescala, tais como LiCoO 2 , LiMn 2 O 4 , LiMnO 2 , LiV 2 O 5 e LiFePO 4 .Commercially available lithium ion cells, which are the most advanced among rechargeable batteries available so far, employ microcrystalline transition metal oxides as cathodes, which function as Li insertion hosts. In search for better electrochemical performance the use of nanomaterials in place of these conventional ones has emerged as excellent alternative. In this review we present a brief introduction about the motivations to use nanostructured materials as cathodes in lithium ion batteries. To illustrate such advantages we present some examples of research directed toward preparations and electrochemical data of the most used cathodes in nanoscale, such as LiCoO 2 , LiMn 2 O 4 , LiMnO 2 , LiV 2 O 5 e LiFePO 4 .Keywords: nanotechnology, lithium-ion battery, cathode, nanoparticles Initial RemarksSince Sony introduced its 18650 cell in 1990, 1 Li-ion batteries with excellent electrochemical performance have been manufactured and occupied a prime position in the market place 2 to power portable and non-portable devices. [3][4][5] The reason for this relevance is that compared to traditional rechargeable batteries such as, lead acid and Ni-Cd, the lithium-ion battery shows several advantages, such as lighter in weight, smaller in dimension and higher energy density. 1 Moreover, although capacity values may be similar to other rechargeable systems, voltages are approximately three times higher, affording higher energy. 1 In general, the commercial lithium-ion batteries use graphite-lithium composite, Li x C 6 , as anode, lithium cobalt oxide, LiCoO 2 , as cathode and a lithium-ion conducting electrolyte. When the cell is charged, lithium is extracted from the cathode and inserted at the anode. On discharge, the lithium ions are released by the anode and taken up again by the cathode (Figure 1).Owing to the importance of lithium ion batteries, these cells are still object of intense research to enhance their properties and characteristics. The searches focus on all aspects of these batteries, including improved anodes, 6-8 cathodes 9-17 and electrolytes. [18][19][20][21][22] However, most of these efforts are concentrated in new cathode materials, since the most used cathode material (LiCoO 2 ) is expensive and is somewhat toxic.The active catho...

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“…These compounds, with relatively open frameworks, are of particular interest as cathode materials in lithium batteries and electrochromic devices. We have also shown that the tetramethylammonium ion is capable of providing a range of new vanadium oxides, LixW2-yO4-y.H20 (Chirayil, Zavalij & Whittingham, 1996a) and (Chirayil, Zavalij & Whittingham, 1996b), and their intercalates [N(CH3)a]V4OI0 (Zavalij, Whittingham, Boylan, Pecharskii & Jacobson, 1996), [N(CH3)4]V307 (Zavaiij, Chirayil & Whittingham, 1997). This work presents the crystal structure of a new zinc hydroxide pyrovanadate, which was found during systematic investigations of the hydrothermal interactions in the system ZnC12-V205-[N(CH3)a]OH.…”

Section: Commentmentioning

confidence: 99%