n‐Butyllithium—An Effective, General Cathode Screening Agent

Whittingham, M. Stanley; Dines, Martin B.

doi:10.1149/1.2133659

Cited by 161 publications

(121 citation statements)

References 13 publications

(14 reference statements)

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“…This vacuum-dried TiO 2 is referred to as VD-TiO 2 . The chemically lithiated amorphous sample was prepared by first dispersing the VD-TiO 2 in hexane ͑anhydrous 95 + %, Aldrich͒, after which an excess n-butyllithium ͑1.6 M Aldrich͒ 12,13 was slowly added while stirring the mixture. This method allows insertion of lithium in a chemical way by an electrochemical driving force.…”

Section: Methodsmentioning

confidence: 99%

Lithium Storage in Amorphous TiO[sub 2] Nanoparticles

Borghols

Lützenkirchen‐Hecht

Haake

et al. 2010

J. Electrochem. Soc.

158

185

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Amorphous titanium oxide nanoparticles were prepared from titanium isopropoxide. In situ measurements reveal an extraordinary high capacity of 810 mAh/g on the first discharge. Upon cycling at a charge/discharge rate of 33.5 mA/g, this capacity gradually decreases to 200 mAh/g after 50 cycles. The origin of this fading was investigated using X-ray absorption spectroscopy and solid-state nuclear magnetic resonance. These measurements reveal that a large fraction of the total amount of the consumed Li atoms is due to the reaction of H 2 O/OH species adsorbed at the surface to Li 2 O, explaining the irreversible capacity loss. The reversible capacity of the bulk, leading to the Li 0.5 TiO 2 composition, does not explain the relatively large reversible capacity, implying that part of Li 2 O at the TiO 2 surface may be reversible. The high reversible capacity, also at large ͑dis͒charge rates up to 3.35 A/g ͑10C͒, makes this amorphous titanium oxide material suitable as a low cost electrode material in a high power battery. © 2010 The Electrochemical Society. ͓DOI: 10.1149/1.3332806͔ All rights reserved. Electrochemical storage devices based upon lithium-ion technology have replaced earlier battery types in numerous applications, e.g., portable devices, mainly due to their high energy density, long cycle life, and their relatively low impact on the environment. If materials that support higher current densities during discharging and satisfy the safety issues concerned, Li-ion batteries would become available for heavy duty applications such as ͑hybrid͒ electrical cars.A high power density requires both good ionic and electronic transport properties of the electrode materials. In many cases, the solid-state diffusion of Li ions through the electrode materials is several orders of magnitude smaller than in the electrolyte. Therefore, if the power density is to be improved, the electrode performance is to be investigated. In commercially available Li-ion batteries, the electrode material is dispersed in the electrolyte as microsized crystallites, which are capable of hosting the lithium ions inside their crystalline voids. By simply decreasing the size of these crystallites, the electrode-electrolyte interface is increased, whereas the diffusion length inside the electrode crystallite decreases. However, recent studies reveal a more complex behavior of nanosized Li insertion compounds in, e.g., TiO 2 anatase, 1-3 TiO 2 rutile, 4,5 or Li x FePO 4 , 6 showing distinct changes in electronic structure and ionic mobility upon downsizing to the nanodomain. 7 Usually, these differences in electronic structure and ionic mobility between bulk and nanosized crystallites are ascribed to the relatively increased impact of surface phenomena. [8][9][10] Between the crystalline structures anatase and rutile TiO 2 , similarities were observed in the physical behavior of the nanoscale compounds. Both reveal an increased Liion capacity compared to their microscale counterparts, which appears to be facilitated by an anomalous phase behavi...

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Section: Methodsmentioning

confidence: 99%

Lithium Storage in Amorphous TiO[sub 2] Nanoparticles

Borghols

Lützenkirchen‐Hecht

Haake

et al. 2010

J. Electrochem. Soc.

158

185

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“…Nanostructured TiO 2 anatase obtained from Altair (40 nm) was chemically lithiated with n-butyllithium [33] and investigated with neutron diffraction (GEM, ISIS [34] ) and 7 Li (I = 3/2, 92.6 % abundance) NMR spectroscopy. The TiO 2 powder was mixed with hexane (anhydrous 95 + %, Aldrich), and the n-butyllithium was added slowly while the mixture was stirred to guarantee homogeneous lithiation of the material.…”

Section: Methodsmentioning

confidence: 99%

The Influence of Size on Phase Morphology and Li‐Ion Mobility in Nanosized Lithiated Anatase TiO₂

Wagemaker

Borghols

Eck

et al. 2007

Chemistry A European J

101

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Sustainable energy storage in the form of Li-ion batteries requires new and advanced materials in particular with a higher power density. Nanostructuring appears to be a promising strategy, in which the higher power density in nanosized materials is related to the dramatically shortened Li-ion diffusion paths. However, nanosizing materials also changes intrinsic material properties, which influence both ionic and electronic conductivity. In this work neutron diffraction is used to show that in addition to these two aspects, nanostructuring changes the phase behavior and morphology. Lithiated 40-nm TiO(2) anatase crystallites become single phase, either having the Li-poor original anatase phase, or the Li-rich Li-titanate phase, in contrast to microsized crystallites where these two phases coexist in equilibrium within one crystal particle. In addition, Li(x)TiO(2) compositions occur with stoichiometries that are not stable in micron-sized crystallites, indicating enhanced solid solution behavior. Reduced conduction electron densities at the sites of the Li ions are observed by NMR spectroscopy. This is accompanied by reduced spontaneous Li-ion mobility, suggesting a correlation between the electron density at the Li-ion site and the Li-ion mobility. The present results show that in the case of lithiated anatase TiO(2), significant effects on phase composition, morphology, and electronic configurations are induced, as well as slower intracrystallite Li diffusion.

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“…brookite and rutile can intake only small amounts of lithium, while the anatase form and the synthetic polymorph TiO 2 (B) react extensively with stoichiometries up to 0.8-1 Li per Ti [10][11][12]. Out of all these compositions, Li 4 Ti 5 O 12 exhibits the best behavior as an anode with a theoretical capacity of 175 mAh/g.…”

Section: Introductionmentioning

confidence: 99%