Electrochemical and In Situ XAFS-XRD Investigation of Nb[sub 2]O[sub 5] for Rechargeable Lithium Batteries

Kodama, Ryoji; Terada, Yasuko; Nakai, Izumi; Komaba, Shinichi; Kumagai, Naoya

doi:10.1149/1.2163788

Cited by 168 publications

(169 citation statements)

References 21 publications

(20 reference statements)

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“…The increase in impedance with continued cycling suggests that some reaction between LLZNO and Li electrodes had occurred. It is known that Nb 5+ can be reduced to Nb 4+ at relatively low potentials (Kodama et al, 2006;Wang et al, 2011). Therefore, the reduction of Nb 5+ may adversely affect charge transport in LLZNO and/or the formation of a passivating layer.…”

Section: Cycling and Electrochemical Impedancementioning

confidence: 99%

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

et al. 2016

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The electrochemical stability of Li6.5La3Zr1.5Nb0.5O12 (LLZNO) and Li6.5La3Zr1.5Ta0.5O12 (LLZTO) against metallic Li was studied using direct current (DC) and electrochemical impedance spectroscopy (EIS). Dense polycrystalline LLZNO (ρ = 97%) and LLZTO (ρ = 92%) were made using sol-gel synthesis and rapid induction hot-pressing at 1100°C and 15.8 MPa. During DC cycling tests at room temperature (± 0.01 mA/cm 2 for 36 cycles), LLZNO exhibited an increase in Li-LLZNO interface resistance and eventually short-circuiting while the LLZTO was stable. After DC cycling, LLZNO appeared severely discolored while the LLZTO did not change in appearance. We believe the increase in Li-LLZNO interfacial resistance and discoloration are due to reduction of Nb 5+ to Nb 4+ . The negligible change in interfacial resistance and no color change in LLZTO suggest that Ta 5+ may be more stable against reduction than Nb 5+ in cubic garnet versus Li during cycling.

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Section: Cycling and Electrochemical Impedancementioning

confidence: 99%

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

et al. 2016

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“…Nb 2 O 5 could find applications in low voltage (2 V range) applications such as microelectronic or memory back up [2] systems. Different polymorphs of Nb 2 O 5 compounds that have been studied are pseudo-hexagonal (H), orthorhombic (O), tetragonal (T), and monoclinic (M) [2,3]. Kodama et al [3] found that O-Nb 2 O 5 particles possess superior cycling performance compared to M-Nb 2 O 5 particles.…”

Section: Introductionmentioning

confidence: 99%

“…Different polymorphs of Nb 2 O 5 compounds that have been studied are pseudo-hexagonal (H), orthorhombic (O), tetragonal (T), and monoclinic (M) [2,3]. Kodama et al [3] found that O-Nb 2 O 5 particles possess superior cycling performance compared to M-Nb 2 O 5 particles. In our previous work, we made an opposite observation in the case of bare and Ta-doped Nb 2 O 5 nanofibers [4,5].…”

Section: Introductionmentioning

confidence: 99%

Studies on the lithium ion diffusion coefficients of electrospun Nb2O5 nanostructures using galvanostatic intermittent titration and electrochemical impedance spectroscopy

Reddy

Jose

Viet

et al. 2014

Electrochimica Acta

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“…16,17 However, the kinetics of this material had never been determined. The results with mesoporous films indicated that not only that Li + insertion was extremely rapid but also that mesoporous crystalline materials (orthorhombic T-phase) had much better kinetics and charge storage properties than the corresponding mesoporous amorphous films.…”

Section: Capacitive Energy Storagementioning

confidence: 99%

Panoramic View of Electrochemical Pseudocapacitor and Organic Solar Cell Research in Molecularly Engineered Energy Materials (MEEM)

et al. 2014

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Our program on capacitive energy storage is a comprehensive one that combines experimental and computational components to achieve a fundamental understanding of charge storage processes in redox-based materials, specifically transition metal oxides. Some of the highlights of this program are the identification of intercalation pseudocapacitance in Nb 2 O 5 , which enables high energy density to be achieved at high rates, and the development of a new route for synthesizing mesoporous films in which preformed nanocrystal building blocks are used in combination with polymer templating. The resulting material architectures have large surface areas and enable electrolyte access to the redox active pore walls, while the interconnected mesoporous film provides good electronic conductivity. Select first-principles density-functional theory studies of prototypical pseudocapacitor materials are reviewed, providing insight into the key physical and chemical features involved in charge transfer and ion diffusion. Rigorous multiscale physical models and numerical tools have been developed and used to reproduce electrochemical properties of carbon-based electrochemical capacitors with the ultimate objective of facilitating the optimization of electrode design. For the organic photovoltaic (OPV) program, our focus has been ongoing beyond the trial-and-error Edisonian approaches that have been responsible for the increase in power conversion efficiency of blend-cast (BC) bulk heterojunction blends of polymers and fullerenes. Our first approach has been to use molecular self-assembly to create the ideal nanometer-scale architecture using thermodynamics rather than relying on the kinetics of spontaneous phase segregation. We have created fullerenes that self-assemble into one-dimensional stacks and have shown that use of these self-assembled fullerenes lead to dramatically enhanced OPV performance relative to fullerenes that do not assemble. We also have created self-assembling conjugated polymers that form gels based on electrically continuous cross-linked micelles in solution, opening the possibility for water-processable "green" production of OPVs based on these materials. Our second approach has been to avoid kinetic control over phase separation by using a sequential processing (SqP) technique to deposit the polymer and fullerene materials in separate deposition steps. The polymer layer is deposited first, using solvents and deposition conditions that optimize the polymer crystallinity for swelling and hole mobility. The fullerene layer is then deposited in a second step from a solvent that swells the polymer but does not dissolve it, allowing the fullerene to penetrate into the polymer underlayer to the desired degree. Careful comparison of composition-and thickness-matched BC and SqP devices shows that SqP not only produces more efficient devices but also leads to devices that behave more consistently.

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Electrochemical and In Situ XAFS-XRD Investigation of Nb[sub 2]O[sub 5] for Rechargeable Lithium Batteries

Cited by 168 publications

References 21 publications

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

Studies on the lithium ion diffusion coefficients of electrospun Nb2O5 nanostructures using galvanostatic intermittent titration and electrochemical impedance spectroscopy

Panoramic View of Electrochemical Pseudocapacitor and Organic Solar Cell Research in Molecularly Engineered Energy Materials (MEEM)

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