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Title: In Situ Tracking Kinetic Pathways of Li + /Na + Substitution during Ion-Exchange Synthesis of Li xNa 1.5–x VOPO 4 F 0.5

Abstract

Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li +/Na + substitution during solvothermal ion-exchange synthesis of Li xNa 1.5-xVOPO 4F 0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-time observation, corroborated by first-principles calculations, reveals a selective replacement of Na + by Li +, leading to peculiar Na +/Li +/vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials.

Authors:
 [1];  [2];  [3];  [4];  [3];  [4];  [5];  [6];  [3]; ORCiD logo [4]; ORCiD logo [3]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States); Seoul National Univ. (Korea, Republic of)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Seoul National Univ. (Korea, Republic of)
  5. Koreal Atomic Energy Research Inst. (Korea, Republic of)
  6. Brookhaven National Lab. (BNL), Upton, NY (United States); Koreal Atomic Energy Research Inst. (Korea, Republic of)
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1389228
Report Number(s):
BNL-114157-2017-JA; BNL-114529-2017-JA
Journal ID: ISSN 0002-7863; TRN: US1702362
Grant/Contract Number:
SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 36; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE

Citation Formats

Park, Young-Uk, Bai, Jianming, Wang, Liping, Yoon, Gabin, Zhang, Wei, Kim, Hyungsub, Lee, Seongsu, Kim, Sung-Wook, Looney, J. Patrick, Kang, Kisuk, and Wang, Feng. In Situ Tracking Kinetic Pathways of Li + /Na + Substitution during Ion-Exchange Synthesis of LixNa1.5–x VOPO 4 F 0.5. United States: N. p., 2017. Web. doi:10.1021/jacs.7b05302.
Park, Young-Uk, Bai, Jianming, Wang, Liping, Yoon, Gabin, Zhang, Wei, Kim, Hyungsub, Lee, Seongsu, Kim, Sung-Wook, Looney, J. Patrick, Kang, Kisuk, & Wang, Feng. In Situ Tracking Kinetic Pathways of Li + /Na + Substitution during Ion-Exchange Synthesis of LixNa1.5–x VOPO 4 F 0.5. United States. doi:10.1021/jacs.7b05302.
Park, Young-Uk, Bai, Jianming, Wang, Liping, Yoon, Gabin, Zhang, Wei, Kim, Hyungsub, Lee, Seongsu, Kim, Sung-Wook, Looney, J. Patrick, Kang, Kisuk, and Wang, Feng. 2017. "In Situ Tracking Kinetic Pathways of Li + /Na + Substitution during Ion-Exchange Synthesis of LixNa1.5–x VOPO 4 F 0.5". United States. doi:10.1021/jacs.7b05302.
@article{osti_1389228,
title = {In Situ Tracking Kinetic Pathways of Li + /Na + Substitution during Ion-Exchange Synthesis of LixNa1.5–x VOPO 4 F 0.5},
author = {Park, Young-Uk and Bai, Jianming and Wang, Liping and Yoon, Gabin and Zhang, Wei and Kim, Hyungsub and Lee, Seongsu and Kim, Sung-Wook and Looney, J. Patrick and Kang, Kisuk and Wang, Feng},
abstractNote = {Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li+/Na+ substitution during solvothermal ion-exchange synthesis of LixNa1.5-xVOPO4F0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-time observation, corroborated by first-principles calculations, reveals a selective replacement of Na+ by Li+, leading to peculiar Na+/Li+/vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials.},
doi = {10.1021/jacs.7b05302},
journal = {Journal of the American Chemical Society},
number = 36,
volume = 139,
place = {United States},
year = 2017,
month = 8
}

Journal Article:
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  • Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li +/Na + substitution during solvothermal ion-exchange synthesis of Li xNa 1.5-xVOPO 4F 0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-timemore » observation, corroborated by first-principles calculations, reveals a selective replacement of Na + by Li +, leading to peculiar Na +/Li +/vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials.« less
  • Observation of wide angle diffraction data collected in situ during previous synthesis of Na-CST (Na{sub 2}Ti{sub 2}SiO{sub 7}-2H{sub 2}O) showed initial crystallization of a precursor phase (SNT) at 30 C followed by conversion to CST after 1 h at 220 C. In situ studies of Cs{sup +} ion exchange into the H{sup +} form of CST showed a site-by-site ion exchange pathway accompanied by a simultaneous structural transition from P4{sub 2}/mbc (cell parameters a = 11.0690(6) Angstroms, c = 11.8842(6) Angstroms) to P4{sub 2}/mcm (cell parameters a = 7.847(2) Angstroms, c = 11.9100(6) Angstroms). After approximately 18% Cs{sup +} exchangemore » into site designated Cs2 in space group P4{sub 2}/mcm, a site designated Cs1 in space group P4{sub 2}/mcm began to fill at the center of the 8MR windows until a maximum of approximately 22% exchange was achieved for Cs1. Bond valence sums of site Cs1 to framework O{sup 2-} are 1.00 v.u., while bond valence sums of site Cs2 to framework O{sup 2-} are 0.712 v.u. suggesting Cs1 to have a more stable bonding environment.« less
  • Two layered copper vanadium phosphates, Cu{sub 0.5}[OPO{sub 4}]{center_dot}2H{sub 2}O (1) and Cu{sub 0.5}(OH){sub 0.5}[VOPO{sub 4}]{center_dot}2H{sub 2}O (2), have been synthesized hydrothermally and their structures determined by single-crystal X-ray crystallography. Phosphate 1 is monoclinic, space group P2{sub 1}/m, a = 6.614 (2) {angstrom}, b = 8.930(2) {angstrom}, c = 9.071(2) {angstrom}, {beta} = 103.79(2){degrees}, Z = 4, V = 520.3(3) {angstrom}{sup 3}. Refinement with 750 observed reflections for which I{ge}3{sigma}(I) gave R(R{sub w}) = 0.051(0.058). The structure has hydrated Cu{sup 2+} ions bonded to layers composed of distorted VO{sub 6} octahedra and PO{sub 4} tetrahedra. Each Cu{sup 2+} ion is bondedmore » to only one layer and possesses a nearly square planar geometry but with two very long axial bonds. This results in a very distorted octahedral configuration composed of two phosphate oxygens, three water molecules, and one vanadyl oxygen. Phosphate 2 is triclinic, space group P{bar 1}, a = 7.0124(8) {angstrom}, b = 12.6474(9) {angstrom}, c = 6.3022(6) {angstrom}, {alpha} = 90.079(8){degrees}, {beta} = 96.076(9){degrees}, {gamma} = 74.002(7){degrees}, Z = 2, V = 534.05(9) {angstrom}{sup 3}. Refinement using 2311 observed reflections with I {ge} 3{sigma}(I) gave R(R{sub w}) = 0.035 (0.043). The structure consists of VOPO{sub 4} layers somewhat similar to those of 1, but with the layers bridges together through Cu dimers of Cu{sub 2}(OH){sub 2}(H{sub 2}O){sub 4}. Each Cu{sup 2+} ion is in a distorted square planar configuration.« less