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5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on TiNb2O7 by Materials Project

TiNb2O7 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are three inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.74–2.28 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with two NbO6 octahedra, edges with two equivalent TiO6 octahedra, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 4–29°. There are a spread of Ti–O bond distances ranging from 1.79–2.21 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with two NbO6 octahedra, edges with two equivalent TiO6 octahedra, and edges with two NbO6 octahedra. The corner-sharing octahedra tilt angles range from 3–30°. There are a spread of Ti–O bond distances ranging from 1.83–2.28 Å. There are six inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with three NbO6 octahedra, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 3–31°. There are a spread of Nb–O bond distances ranging from 1.85–2.26 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with four NbO6 octahedra, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 4–30°. There are a spread of Nb–O bond distances ranging from 1.84–2.25 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with two TiO6 octahedra, corners with three NbO6 octahedra, and an edgeedge with one NbO6 octahedra. The corner-sharing octahedra tilt angles range from 6–30°. There are a spread of Nb–O bond distances ranging from 1.87–2.33 Å. In the fourth Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with four NbO6 octahedra and edges with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 15–30°. There are a spread of Nb–O bond distances ranging from 1.84–2.32 Å. In the fifth Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 2–15°. There are a spread of Nb–O bond distances ranging from 1.93–2.08 Å. In the sixth Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with four NbO6 octahedra, an edgeedge with one TiO6 octahedra, and an edgeedge with one NbO6 octahedra. The corner-sharing octahedra tilt angles range from 4–30°. There are a spread of Nb–O bond distances ranging from 1.87–2.26 Å. There are twenty-one inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+ and two equivalent Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+ and two equivalent Nb5+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb5+ atoms. In the seventh O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the eighth O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the ninth O2- site, O2- is bonded in a linear geometry to one Ti4+ and one Nb5+ atom. In the tenth O2- site, O2- is bonded in a linear geometry to one Ti4+ and one Nb5+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to three Ti4+ and one Nb5+ atom. In the twelfth O2- site, O2- is bonded to two equivalent Ti4+ and two Nb5+ atoms to form distorted corner-sharing OTi2Nb2 tetrahedra. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+ and two Nb5+ atoms. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+ and two Nb5+ atoms. In the fifteenth O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the sixteenth O2- site, O2- is bonded in a linear geometry to one Ti4+ and one Nb5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Ti4+ atoms. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+ and two equivalent Nb5+ atoms. In the nineteenth O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the twentieth O2- site, O2- is bonded in a linear geometry to one Ti4+ and one Nb5+ atom. In the twenty-first O2- site, O2- is bonded in a linear geometry to one Ti4+ and one Nb5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Translating a Material Discovery into a Commercial Product in the Modern Lithium-ion Battery Market

Lithium-ion batteries are essential for portable technology and are now poised to disrupt a century of combustion-based transportation. The electrification revolution could eliminate our reliance on fossil fuels and enable a clean energy future; advanced batteries would facilitate this transition. However, owing to the demanding performance, cost, and safety requirements, it is challenging to translate new materials from laboratory prototypes to commercial products. This Perspective describes that journey toward commercialization for a new lithium-ion battery anode material, TiNb2O7 (TNO). TNO is intended as an alternative to graphite or Li4Ti5O12 with better rate and safety characteristics than the former, and higher energy density than the latter. The high capacity of TNO stems from multielectron redox of Nb5+ to Nb3+, its operating voltage window well above Li+/Li reduction potential prevents lithium dendrite formation, and its open crystal structure leads to high-power performance. Nevertheless, the creation of a practical TNO anode was non-linear and non-trivial. Its history is built on 30 years on fundamental science that preceded its application as a battery, and its battery development included a nearly 30-year gap. The insights and lessons 2 contained in this Perspective, many of them acquired firsthand, serve two purposes: (i) to unite the disparate studies of TiNb2O7 into a coherent modern understanding relevant to its application as a battery material and (ii) to highlight some of the considerations of commercializing a new material that affect TiNb2O7 as well as new electrode candidates more generally.

Griffith, Kent J.↗
DOE OSTI2023

Crystallographic Insight of Reduced Lattice Volume Expansion in Mesoporous Cu 2+ -Doped TiNb 2 O 7 Microspheres during Li + Insertion

TiNb 2 O 7 represents a promising anode material for lithium-ion batteries (LIBs), but its practical applications are currently hampered by the non-negligible volumetric expansion and contraction during the charge/discharge process and the sluggish ion/electron kinetics. Here a combination technique is reported by systematically optimizing the porous and spherical morphology, crystal structure, and surface decoration of mesoporous Cu 2+ -doped TiNb 2 O 7 microspheres to enhance the electrochemical Li + storage performance and stability simultaneously. The Cu 2+ dopants preferentially replace Ti 4+ in crystal lattices, which decreases the Li + diffusion barrier and increases the electronic conductivity, as confirmed by density functional theory (DFT) calculation and demonstrated by diverse electrochemical characterizations. The successful Cu 2+ doping significantly reduces the lattice expansion coefficient from 7.26% to 4.61% after Li + insertion along the b-axis of TiNb 2 O 7 , as visualized from in situ and ex situ XRD analysis. The optimal 5% Cu 2+ -doped TiNb 2 O 7 with surface coating of N-doped carbon exhibits significantly enhanced specific capacity and rate and cyclic performances in both half- and full-cell configurations, demonstrating an excellent electrochemical behavior for fast-charging LIB applications.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Operando Analysis of Gas Evolution in TiNb 2 O 7 (TNO)-Based Anodes for Advanced High-Energy Lithium-Ion Batteries under Fast Charging

TiNb 2 O 7 (TNO) is regarded as one of the promising next-generation anode materials for lithium-ion batteries (LIBs) due to its high rate capabilities, higher theoretical capacity, and higher lithiation voltage. Furthermore, this enables the cycling of TNO-based anodes under extreme fast charging (XFC) conditions with a minimal risk of lithium plating compared to that of graphite anodes. Here, the gas evolution in real time with TNO-based pouch cells is first reported via operando mass spectrometry. The main gases are identified to be CO 2 , C 2 H 4 , and O 2 . A solid–electrolyte interphase is detected on TNO, which continues evolving, forming, and dissolving with the lithiation and delithiation of TNO. The gas evolution can be significantly reduced when a protective coating is applied on the TNO particles, reducing the CO 2 and C 2 H 4 evolution by ~2 and 5 times, respectively, at 0.1C in a half-cell configuration. The reduction on gas generation in full cells is even more pronounced. The surface coating also enables 20% improvement in capacity under XFC conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗