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15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Unconventional polaronic ground state in superconducting LiTi 2 O 4

Geometrically frustrated lattices can display a range of correlated phenomena, ranging from spin frustration and charge order to dispersionless flat bands due to quantum interference. One particularly compelling family of such materials is the half-valence spinel LiB 2 O 4 materials. On the B-site frustrated pyrochlore sublattice, the interplay of correlated metallic behavior and charge frustration leads to a superconducting state in LiTi 2 O 4 and heavy fermion behavior in LiV 2 O 4 . To date, however, LiTi 2 O 4 has primarily been understood as a conventional BCS superconductor despite a lattice structure that could host more exotic ground states. Here, we present a multimodal investigation of LiTi 2 O 4 , combining ARPES, RIXS, proximate magnetic probes, and ab-initio many-body theoretical calculations. Our data reveals a novel mobile polaronic ground state with spectroscopic signatures that underlie co-dominant electron-phonon coupling and electron-electron correlations also found in the lightly doped cuprates. The cooperation between the two interaction scales distinguishes LiTi 2 O 4 from other superconducting titanates, suggesting an unconventional origin to superconductivity in LiTi 2 O 4 . Our work deepens our understanding of the rare interplay of electron-electron correlations and electron-phonon coupling in unconventional superconducting systems. In particular, our work identifies the geometrically frustrated, mixed-valence spinel family as an under-explored platform for discovering unconventional, correlated ground states.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(Si2O5)2 by Materials Project

LiTi(Si2O5)2 crystallizes in the orthorhombic Pnc2 space group. The structure is three-dimensional. Li1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There is two shorter (1.94 Å) and two longer (2.04 Å) Li–O bond length. Ti3+ is bonded to four O2- atoms to form distorted TiO4 trigonal pyramids that share corners with four SiO4 tetrahedra. There is two shorter (1.92 Å) and two longer (1.96 Å) Ti–O bond length. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three SiO4 tetrahedra and a cornercorner with one TiO4 trigonal pyramid. There are a spread of Si–O bond distances ranging from 1.62–1.65 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three SiO4 tetrahedra and a cornercorner with one TiO4 trigonal pyramid. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to one Li1+, one Ti3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(Si2O5)2 by Materials Project

LiTi(Si2O5)2 crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share corners with four SiO4 tetrahedra and edges with two equivalent TiO4 tetrahedra. There is two shorter (1.94 Å) and two longer (1.95 Å) Li–O bond length. Ti3+ is bonded to four O2- atoms to form distorted TiO4 tetrahedra that share corners with four SiO4 tetrahedra and edges with two equivalent LiO4 tetrahedra. All Ti–O bond lengths are 1.92 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one LiO4 tetrahedra, a cornercorner with one TiO4 tetrahedra, and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.64 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one LiO4 tetrahedra, a cornercorner with one TiO4 tetrahedra, and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.64 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to one Li1+, one Ti3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the sixth O2- site, O2- is bonded in a linear geometry to two equivalent Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SO4)2 by Materials Project

LiTi(SO4)2 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.60 Å. In the second Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.73 Å. In the third Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.96–2.56 Å. In the fourth Li1+ site, Li1+ is bonded to six O2- atoms to form distorted LiO6 pentagonal pyramids that share corners with four TiO6 octahedra, corners with two SO4 tetrahedra, and edges with two SO4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–56°. There are a spread of Li–O bond distances ranging from 1.95–2.28 Å. There are four inequivalent Ti3+ sites. In the first Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one LiO6 pentagonal pyramid and corners with six SO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 2.01–2.15 Å. In the second Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one LiO6 pentagonal pyramid and corners with six SO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 1.99–2.10 Å. In the third Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six SO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 2.02–2.12 Å. In the fourth Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent LiO6 pentagonal pyramids and corners with six SO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 2.00–2.11 Å. There are eight inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra and a cornercorner with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 38–48°. There are a spread of S–O bond distances ranging from 1.47–1.51 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra and an edgeedge with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 48–51°. There is one shorter (1.45 Å) and three longer (1.51 Å) S–O bond length. In the third S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 45–50°. There are a spread of S–O bond distances ranging from 1.46–1.52 Å. In the fourth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 38–50°. There are a spread of S–O bond distances ranging from 1.43–1.54 Å. In the fifth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 38–50°. There are a spread of S–O bond distances ranging from 1.45–1.51 Å. In the sixth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra and a cornercorner with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 44–47°. There are a spread of S–O bond distances ranging from 1.46–1.52 Å. In the seventh S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 43–47°. There are a spread of S–O bond distances ranging from 1.45–1.51 Å. In the eighth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three TiO6 octahedra and an edgeedge with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 35–48°. There are a spread of S–O bond distances ranging from 1.45–1.53 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one S6+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+ and one S6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one S6+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one S6+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ti3+, and one S6+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one S6+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Li1+ and one S6+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Li1+ and one S6+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ti3+, and one S6+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ti3+, and one S6+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one S6+ atom. In the fifteenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one S6+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the seventeenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the eighteenth O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one S6+ atom. In the twentieth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the twenty-first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the twenty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ti3+, and one S6+ atom. In the twenty-third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one S6+ atom. In the twenty-fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Li1+ and one S6+ atom. In the twenty-fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one S6+ atom. In the twenty-sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one S6+ atom. In the twenty-seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ti3+ and one S6+ atom. In the twenty-eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ti3+ and one S6+ atom. In the twenty-ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ti3+, and one S6+ atom. In the thirtieth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ti3+, and one S6+ atom. In the thirty-first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one S6+ atom. In the thirty-second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one S6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SiO3)2 by Materials Project

LiTiSi2O6 is Esseneite structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Li1+ is bonded to six O2- atoms to form distorted LiO6 octahedra that share corners with four equivalent SiO4 tetrahedra, edges with three equivalent TiO6 octahedra, and edges with two equivalent SiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 2.10–2.37 Å. Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six equivalent SiO4 tetrahedra, edges with two equivalent TiO6 octahedra, and edges with three equivalent LiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.97–2.13 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent LiO6 octahedra, corners with three equivalent TiO6 octahedra, corners with two equivalent SiO4 tetrahedra, and an edgeedge with one LiO6 octahedra. The corner-sharing octahedra tilt angles range from 29–61°. There is one shorter (1.61 Å) and three longer (1.65 Å) Si–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to one Li1+, one Ti3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Li1+, two equivalent Ti3+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SeO)2 by Materials Project

LiO2TiSe2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one LiO2 sheet oriented in the (0, 0, 1) direction and one TiSe2 sheet oriented in the (0, 0, 1) direction. In the LiO2 sheet, Li is bonded in a distorted hexagonal planar geometry to six equivalent O atoms. There are two shorter (2.07 Å) and four longer (2.09 Å) Li–O bond lengths. O is bonded in a trigonal non-coplanar geometry to three equivalent Li atoms. In the TiSe2 sheet, Ti is bonded to six equivalent Se atoms to form edge-sharing TiSe6 octahedra. All Ti–Se bond lengths are 2.55 Å. Se is bonded in a distorted T-shaped geometry to three equivalent Ti atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SO)2 by Materials Project

LiO2TiS2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one LiO2 sheet oriented in the (0, 0, 1) direction and one TiS2 sheet oriented in the (0, 0, 1) direction. In the LiO2 sheet, Li1+ is bonded to six equivalent O2- atoms to form edge-sharing LiO6 octahedra. There are four shorter (1.91 Å) and two longer (2.51 Å) Li–O bond lengths. O2- is bonded in a 4-coordinate geometry to three equivalent Li1+ and one O2- atom. The O–O bond length is 1.37 Å. In the TiS2 sheet, Ti3+ is bonded to six equivalent S atoms to form edge-sharing TiS6 octahedra. There are two shorter (2.42 Å) and four longer (2.46 Å) Ti–S bond lengths. S is bonded in a distorted T-shaped geometry to three equivalent Ti3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SO)2 by Materials Project

LiO2TiS2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one LiO2 sheet oriented in the (0, 0, 1) direction and one TiS2 sheet oriented in the (0, 0, 1) direction. In the LiO2 sheet, Li1+ is bonded to six equivalent O2- atoms to form edge-sharing LiO6 octahedra. There are four shorter (1.91 Å) and two longer (2.56 Å) Li–O bond lengths. O2- is bonded in a 4-coordinate geometry to three equivalent Li1+ and one O2- atom. The O–O bond length is 1.38 Å. In the TiS2 sheet, Ti3+ is bonded to six equivalent S atoms to form edge-sharing TiS6 octahedra. There are two shorter (2.42 Å) and four longer (2.46 Å) Ti–S bond lengths. S is bonded in a distorted T-shaped geometry to three equivalent Ti3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SiO3)2 by Materials Project

LiTiSi2O6 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Li1+ is bonded to six O2- atoms to form distorted LiO6 octahedra that share corners with six SiO4 tetrahedra, edges with three equivalent TiO6 octahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 2.04–2.52 Å. Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six SiO4 tetrahedra, edges with two equivalent TiO6 octahedra, and edges with three equivalent LiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.98–2.13 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent TiO6 octahedra, corners with four equivalent LiO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–76°. There is one shorter (1.62 Å) and three longer (1.66 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent LiO6 octahedra, corners with three equivalent TiO6 octahedra, corners with two equivalent SiO4 tetrahedra, and an edgeedge with one LiO6 octahedra. The corner-sharing octahedra tilt angles range from 30–59°. There are a spread of Si–O bond distances ranging from 1.61–1.65 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Li1+, two equivalent Ti3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one Ti3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Li1+, two equivalent Ti3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to one Li1+, one Ti3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two equivalent Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SiO3)2 by Materials Project

LiTiSi2O6 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Li–O bond distances ranging from 1.97–2.77 Å. In the second Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 2.03–2.53 Å. There are two inequivalent Ti3+ sites. In the first Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with five SiO4 tetrahedra, an edgeedge with one TiO6 octahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 1.94–2.26 Å. In the second Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 2.07–2.11 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three TiO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–51°. There are a spread of Si–O bond distances ranging from 1.61–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three TiO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 29–54°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two TiO6 octahedra, corners with two SiO4 tetrahedra, and an edgeedge with one TiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–63°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to one Li1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti3+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Ti3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Li1+, two Ti3+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to one Li1+, two Ti3+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Li1+, one Ti3+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+ and two Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Degradation Mechanism of Phosphate‐Based Li‐NASICON Conductors in Alkaline Environment

NASICON-type Li conductors (Li-NASICON) have traditionally been regarded as promising candidates for solid-state Li-air battery applications because of their stability in water and ambient air. However, the presence of water in the cathode of a Li-air battery can induce a highly alkaline environment by modifying the discharge product from Li 2 O 2 to LiOH which can potentially degrade cathode and separator materials. This study investigates the alkaline stability of common Li-NASICON chemistries through a systematic experimental study of LiTi x Ge 2-x (PO 4 ) 3 (LTGP) with varying x = 0–2.0. Density functional theory calculations are combined to gain a mechanistic understanding of the alkaline instability. It is demonstrated that the instability of LTGP in an alkaline environment is mainly driven by the dissolution of PO 4 3– groups, which subsequently precipitate as Li 3 PO 4 . The introduction of Ti facilitates the formation of a Ti-rich compound on the surface that eventually passivates the material, but only after significant bulk degradation. Consequently, phosphate-based Li-NASICON materials exhibit limited alkaline stability, raising concerns about their viability in humid Li-air batteries.

25 ENERGY STORAGE↗
DOE OSTI2020

Materials Data on LiTi(PO3)4 by Materials Project

LiTi(PO3)4 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Li1+ is bonded in a distorted water-like geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.86–2.65 Å. Ti3+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 2.00–2.17 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 17°. There are a spread of P–O bond distances ranging from 1.48–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 13–21°. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are a spread of P–O bond distances ranging from 1.48–1.62 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–46°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to one Ti3+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Li1+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a distorted linear geometry to one Ti3+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Ti3+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to one Ti3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(PO3)4 by Materials Project

LiTi(PO3)4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Li1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.90–2.56 Å. Ti3+ is bonded to six O2- atoms to form distorted TiO6 pentagonal pyramids that share corners with six PO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 2.03–2.40 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO6 pentagonal pyramids and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO6 pentagonal pyramids and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one TiO6 pentagonal pyramid and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one TiO6 pentagonal pyramid and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Li1+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Ti3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to one Ti3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ti3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(PO3)4 by Materials Project

LiTi(PO3)4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Li1+ is bonded in a distorted L-shaped geometry to two equivalent O2- atoms. There is one shorter (1.90 Å) and one longer (1.97 Å) Li–O bond length. Ti3+ is bonded to seven O2- atoms to form TiO7 pentagonal bipyramids that share corners with seven PO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 2.07–2.24 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO7 pentagonal bipyramids and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO7 pentagonal bipyramids and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.48–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one TiO7 pentagonal bipyramid and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO7 pentagonal bipyramids and corners with two PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Ti3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ti3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Li1+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Ti3+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted linear geometry to one Ti3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(PO3)4 by Materials Project

LiTi(PO3)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.90–2.45 Å. Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 2.07–2.11 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent TiO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 30–39°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 27°. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+ and two P5+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ti3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Li1+ and one P5+ atom.

36 MATERIALS SCIENCE↗