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Chikaoka Y, Tashiro T, Sawayama S, Kobayashi A, Matsumoto A, Iwama E, Naoi K, Fujii K. A structural study on a specific Li-ion ordered complex in dimethyl carbonate-based dual-cation electrolytes. Phys Chem Chem Phys 2024; 26:3920-3926. [PMID: 38230686 DOI: 10.1039/d3cp05526d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Dimethyl carbonate (DMC) is a linear carbonate solvent commonly used as an electrolyte for electric double-layer capacitors (EDLCs) and Li-ion batteries. However, there are serious problems with the use of DMC as an electrolyte solvent: (1) low ionic conductivity when using Li salts (e.g. LiBF4) and (2) liquid-liquid phase separation when using spiro-type quaternary ammonium salts (e.g. SBPBF4). Dual-cation electrolytes, i.e., bi-salt (SBPBF4 and LiBF4) in DMC, are promising candidates to avoid the phase separation issue and to enhance the total and Li+ conductivities. Herein, we reported a specific Li-ion structure in DMC-based dual-cation electrolytes by combining high-energy X-ray total scattering (HEXTS) and all-atom molecular dynamics (MD) simulations. Quantitative radial distribution function analysis based on experimental and simulation results revealed that the phase-separated SBPBF4/DMC (i.e., the bottom phase of 1 M SBPBF4/DMC) forms long-range ion ordering based on the structured SBP+-BF4- ion pairs. When adding LiBF4 salt into SBPBF4/DMC (i.e., dual-cation electrolyte), the ordered SBP+-BF4- structure disappeared owing to the formation of Li-ion solvation complexes. We found that in the dual-cation electrolyte Li ions form multiple Li+-Li+ ordered complexes in spite of relatively low Li-salt concentration (1 M), being a promising Li+-conducting medium with reduced Li salt usage and low viscosity.
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Affiliation(s)
- Yu Chikaoka
- Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558, Japan.
- Global Innovation Research Organization, Tokyo University of Agriculture & Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Tomoya Tashiro
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
| | - Saki Sawayama
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
| | - Ayana Kobayashi
- Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558, Japan.
| | - Ayuna Matsumoto
- Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558, Japan.
| | - Etsuro Iwama
- Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558, Japan.
- Global Innovation Research Organization, Tokyo University of Agriculture & Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Katsuhiko Naoi
- Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558, Japan.
- Global Innovation Research Organization, Tokyo University of Agriculture & Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Kenta Fujii
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
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Han J, Osugi M, Ikeda N, Fujii K. Lithium salt-concentrated organogels prepared via one-step polymer network formation in acetonitrile-based solutions. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Structural aspect on “Salting-in” mechanism of PEG chains into a phosphonium-based ionic liquid using lithium salt. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ikeda N, Ishikawa A, Fujii K. Polyether-based solid electrolytes with a homogeneous polymer network: effect of the salt concentration on the Li-ion coordination structure. Phys Chem Chem Phys 2022; 24:9626-9633. [PMID: 35403631 DOI: 10.1039/d1cp05351e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report a solid polymer electrolyte with an ideal polyether network that was synthesized by using tetra-functional poly(ethylene glycol) (TetraPEG) and lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) salt. The solid TetraPEG electrolyte had few network defects (<5%) and exhibited high mechanical toughness by enduring approximately 11-fold elongation at a 1 : 10 ratio of Li salt to O atoms of PEG (Li/OPEG). We found that the mechanical properties strongly depend on the Li/OPEG ratio, which mainly contributes to the density of crosslinking points in the electrolyte. Raman spectroscopy and high-energy X-ray total scattering were used with all-atom molecular dynamics simulations to visualize the structural effects of Li-ion coordination in the TetraPEG network. At lower salt contents (Li/OPEG = 1 : 10), Li ions were found to preferentially coordinate with OPEG atoms rather than the TFSA anions to form crown ether-like Li+-PEG complexes as ion pair-free species. With increasing salt content, the TFSA anions partially coordinated with Li ions through O atoms of TFSA (OTFSA) to afford contact ion pairs surrounded by both OPEG and OTFSA atoms. Finally, the ion pairing enhanced mononuclear ion pairs as well as multinuclear ionic aggregates when more Li salt was added. This structural change in the Li-ion complexes was directly reflected by the ion-conducting properties of the electrolyte. The TetraPEG electrolyte composed of the ion pair-free Li+ species (Li/OPEG = 1 : 10) exhibited higher ionic conductivity, and the conductivity gradually decreased with increasing salt content because of extensive ion pairing for both mononuclear contact ion pairs and multinuclear aggregates. Regarding the electrochemical properties, the optimum electrolyte composition to realize a reversible Li deposition/dissolution reaction for a negative electrode was found to be Li/OPEG = 1 : 4.
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Affiliation(s)
- Namie Ikeda
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
| | - Asumi Ishikawa
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
| | - Kenta Fujii
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
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Takano S, Sawayama S, Han J, Fujii K. A Homogeneous Polymer Network Organogel Prepared in the Concentrated Lithium-ion Battery Electrolytes Using a Nonflammable Fluorinated Solvent. CHEM LETT 2022. [DOI: 10.1246/cl.210815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Saori Takano
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611
| | - Saki Sawayama
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611
| | - Jihae Han
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611
| | - Kenta Fujii
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611
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Suzuki K, Sawayama S, Deguchi Y, Sai R, Han J, Fujii K. A structural and electrochemical study of lithium-ion battery electrolytes using an ethylene sulfite solvent: from dilute to concentrated solutions. Phys Chem Chem Phys 2022; 24:27321-27327. [DOI: 10.1039/d2cp03616a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Coordination structures of Li-ion complexes in ethylene sulfite (ES)-based electrolytes exhibiting the fast charge–discharge behavior.
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Affiliation(s)
- Kenzo Suzuki
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
| | - Saki Sawayama
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
| | - Yuna Deguchi
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
| | - Ryansu Sai
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
| | - Jihae Han
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
| | - Kenta Fujii
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
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Doi T, Fujii R, Inaba M. Improved stability of highly concentrated LiBF4/fluorinated ethyl acetate-based electrolyte solutions with a co-solvent for LiNi0.8Co0.1Mn0.1O2 positive electrodes in lithium ion batteries. J APPL ELECTROCHEM 2021. [DOI: 10.1007/s10800-021-01590-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Li C, Liu G, Wang K, Dong W, Han J, Yu Y, Min Z, Yang C, Lu Z. Electrochemically-Matched and Nonflammable Janus Solid Electrolyte for Lithium-Metal Batteries. ACS APPLIED MATERIALS & INTERFACES 2021; 13:39271-39281. [PMID: 34375074 DOI: 10.1021/acsami.1c08687] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Solid-state batteries based on ceramic electrolytes are promising alternatives to lithium-ion batteries with better safety and energy density. While solid electrolytes such as the garnet-type Li7La3Zr2O12 (LLZO) are chemically stable with lithium metal, their rigidity leads to poor interfacial contact with the cathodes. Nonflammable organic phosphates, however, are characterized by a liquid nature and can immerse the conventional porous cathodes to form a good contact. However, the phosphates are unstable with lithium metal anodes. We design a quasi-solid Janus electrolyte based on the ceramic LLZO and a trimethyl phosphate (TMP) gel which combines the best of both worlds. The electrochemical window of the Janus electrolyte is significantly extended compared with the TMP to accommodate the lithium metal anode. The contact between the cathode and the electrolyte is maintained by the semifluid nature of the TMP gel. A lithium-metal battery with such a Janus electrolyte can stably cycle at room temperature at 1C while still retaining a capacity of 115 mAh g-1 over 100 times. In contrast, the batteries based on LLZO and TMP individually cannot function properly. More importantly, despite the quasi-solid nature, the battery does not contain flammable functional parts and can alleviate the safety concerns of current batteries containing organic-type electrolytes. This work provides a simple but effective strategy for safe, inexpensive, and energy-dense solid-state batteries.
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Affiliation(s)
- Cheng Li
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, P. R. China
| | - Guohua Liu
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, P. R. China
| | - Kai Wang
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, P. R. China
| | - Wei Dong
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, P. R. China
| | - Jinlong Han
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
| | - Yang Yu
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
| | - Zhiwen Min
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
| | - Chunlei Yang
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
| | - Ziheng Lu
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China
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Doi T, Taccori RJ, Fujii R, Nagashima T, Endo T, Kimura Y, Inaba M. Non-Flammable and Highly Concentrated Carbonate Ester-Free Electrolyte Solutions for 5 V-Class Positive Electrodes in Lithium-Ion Batteries. CHEMSUSCHEM 2021; 14:2445-2451. [PMID: 33961342 DOI: 10.1002/cssc.202100523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 04/19/2021] [Indexed: 06/12/2023]
Abstract
Non-flammable and highly concentrated electrolyte solutions were designed using tris(2,2,2-trifluoroethyl) phosphate (TFEP) as a main solvent toward a radical improvement in the safety and energy density of lithium-ion batteries. Unlike conventional carbonate ester-based solutions, simple TFEP-based electrolyte solutions were not intrinsically compatible with 5 V-class LiNi0.5 Mn1.5 O4 positive electrodes, even at high concentrations. Based on the degradation mechanism that was analyzed by Raman spectroscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, a fluorinated diluent of methyl 3,3,3-trifluoropropionate (FMP) was introduced to suppress the decomposition of LiBF4 and TFEP at high potentials. A nearly saturated LiBF4 /TFEP+FMP electrolyte solution with a specific composition improved the charge and discharge performance of a LiNi0.5 Mn1.5 O4 electrode, and the solution structure was studied by pulsed-field-gradient NMR spectroscopy.
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Affiliation(s)
- Takayuki Doi
- Department of Molecular Chemistry and Biochemistry, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan
| | - Romain Jun Taccori
- Department of Molecular Chemistry and Biochemistry, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan
| | - Ryo Fujii
- Department of Molecular Chemistry and Biochemistry, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan
| | - Tsuyoshi Nagashima
- Department of Molecular Chemistry and Biochemistry, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan
| | - Takatsugu Endo
- Department of Molecular Chemistry and Biochemistry, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan
| | - Yoshifumi Kimura
- Department of Molecular Chemistry and Biochemistry, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan
| | - Minoru Inaba
- Department of Molecular Chemistry and Biochemistry, Doshisha University, Kyotanabe, Kyoto, 610-0321, Japan
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