With a worldwide trend towards the efficient use of renewable energies and the rapid expansion of the electric vehicle market, the importance of rechargeable battery technologies, particularly lithium-ion batteries, has steadily increased. In the past few years, a major breakthrough in electrolyte materials was achieved by simply increasing the salt concentration in suitable salt–solvent combinations, offering technical superiority in numerous figures of merit over alternative materials. This long-awaited, extremely simple yet effective strategy can overcome most of the remaining hurdles limiting the present lithium-ion batteries without sacrificing manufacturing efficiency, and hence its impact is now widely felt in the scientific community, with serious potential for industrial development. This Review aims to provide timely and objective information that will be valuable for designing better realistic batteries, including a multi-angle analysis of their advantages and disadvantages together with future perspectives. Emphasis is placed on the pathways to address the remaining technical and scientific issues rather than re-highlighting the many technical advantages.
Subscribe to Journal
Get full journal access for 1 year
only $4.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Xu, K. Nonaqueous liquid electrolytes for lithium-based rechargeable batteries. Chem. Rev. 104, 4303–4417 (2004).
Fong, R., von Sacken, U. & Dahn, J. R. Studies of lithium intercalation into carbons using nonaqueous electrochemical cells. J. Electrochem. Soc. 137, 2009–2013 (1990).
Myung, S.-T., Sasaki, Y., Sakurada, S., Sun, Y.-K. & Yashiro, H. Electrochemical behavior of current collectors for lithium batteries in non-aqueous alkyl carbonate solution and surface analysis by ToF-SIMS. Electrochim. Acta 55, 288–297 (2009).
Xu, K. Electrolytes and interphases in Li-ion batteries and beyond. Chem. Rev. 114, 11503–11618 (2014).
Wang, D. Y. et al. A systematic study of electrolyte additives in Li[Ni1/3Mn1/3Co1/3]O2 (NMC)/graphite pouch cells. J. Electrochem. Soc. 161, A1818–A1827 (2014).
Watanabe, M. et al. Application of ionic liquids to energy storage and conversion materials and devices. Chem. Rev. 117, 7190–7239 (2017).
Hallinan, D. T. & Balsara, N. P. Polymer electrolytes. Annu. Rev. Mater. Res. 43, 503–525 (2013).
Janek, J. & Zeier, W. G. A solid future for battery development. Nat. Energy 1, 16141 (2016).
Manthiram, A., Yu, X. & Wang, S. Lithium battery chemistries enabled by solid-state electrolytes. Nat. Rev. Mater. 2, 16103 (2017).
Yamada, Y. & Yamada, A. Review — superconcentrated electrolytes for lithium batteries. J. Electrochem. Soc. 162, A2406–A2423 (2015).
Zheng, J., Lochala, J. A., Kwok, A., Deng, Z. D. & Xiao, J. Research progress towards understanding the unique interfaces between concentrated electrolytes and electrodes for energy storage applications. Adv. Sci. 4, 1700032 (2017).
Yoshida, K. et al. Oxidative-stability enhancement and charge transport mechanism in glyme-lithium salt equimolar complexes. J. Am. Chem. Soc. 133, 13121–13129 (2011). This work reported enhanced oxidation stability of concentrated electrolytes and clarified the mechanism (the downward sihft of HOMO).
Seo, D. M., Borodin, O., Han, S.-D., Boyle, P. D. & Henderson, W. A. Electrolyte solvation and ionic association II. Acetonitrile-lithium salt mixtures: highly dissociated salts. J. Electrochem. Soc. 159, A1489–A1500 (2012).
Yamada, Y. et al. Unusual stability of acetonitrile-based superconcentrated electrolytes for fast-charging lithium-ion batteries. J. Am. Chem. Soc. 136, 5039–5046 (2014). This work reported enhanced reduction stability of concentrated electrolytes and clarified the mechanism (anion-derived SEI formation).
Yamada, Y. et al. General observation of lithium intercalation into graphite in ethylene-carbonate-free superconcentrated electrolytes. ACS Appl. Mater. Interfaces 6, 10892–10899 (2014).
McOwen, D. W. et al. Concentrated electrolytes: decrypting electrolyte properties and reassessing Al corrosion mechanisms. Energy Environ. Sci. 7, 416–426 (2014).
Zhang, C. et al. Chelate effects in glyme/lithium bis(trifluoromethanesulfonyl)amide solvate ionic liquids, part 2: importance of solvate-structure stability for electrolytes of lithium batteries. J. Phys. Chem. C 118, 17362–17373 (2014).
Yamada, Y., Yaegashi, M., Abe, T. & Yamada, A. A superconcentrated ether electrolyte for fast-charging Li-ion batteries. Chem. Commun. 49, 11194 (2013).
Petibon, R., Aiken, C. P., Ma, L., Xiong, D. & Dahn, J. R. The use of ethyl acetate as a sole solvent in highly concentrated electrolyte for Li-ion batteries. Electrochim. Acta 154, 287–293 (2015).
Wang, J. et al. Superconcentrated electrolytes for a high-voltage lithium-ion battery. Nat. Commun. 7, 12032 (2016). This work demonstrated the reversible operation of 5 V-class batteries with concentrated electrolytes.
Wang, J. et al. Fire-extinguishing organic electrolytes for safe batteries. Nat. Energy 3, 22–29 (2018). This work presented non-flammable and fire-extinguishing organic electrolytes that enabled long-term battery cycling.
Choi, J. W. & Aurbach, D. Promise and reality of post-lithium-ion batteries with high energy densities. Nat. Rev. Mater. 1, 16013 (2016).
Aurbach, D. et al. Review on electrode–electrolyte solution interactions, related to cathode materials for Li-ion batteries. J. Power Sources 165, 491–499 (2007).
Kim, J.-H. et al. Understanding the capacity fading mechanism in LiNi0.5Mn1.5O4/graphite Li-ion batteries. Electrochim. Acta 90, 556–562 (2013).
Wang, X., Yasukawa, E. & Mori, S. Inhibition of anodic corrosion of aluminum cathode current collector on recharging in lithium imide electrolytes. Electrochim. Acta 45, 2677–2684 (2000).
Li, L. et al. Transport and electrochemical properties and spectral features of non-aqueous electrolytes containing LiFSI in linear carbonate solvents. J. Electrochem. Soc. 158, A74–A82 (2011).
Matsumoto, K. et al. Suppression of aluminum corrosion by using high concentration LiTFSI electrolyte. J. Power Sources 231, 234–238 (2013). This work demonstrated the corrosion prevention of an Al current collector in concentrated electrolytes.
Suo, L., Hu, Y.-S., Li, H., Armand, M. & Chen, L. A new class of solvent-in-salt electrolyte for high-energy rechargeable metallic lithium batteries. Nat. Commun. 4, 1481 (2013). This work reported less solubility of lithium polysulfide in concentrated electrolytes to achieve better cycling of lithium-sulfur batteries.
Dokko, K. et al. Solvate ionic liquid electrolyte for Li-S batteries. J. Electrochem. Soc. 160, A1304–A1310 (2013). This work reported the dilution of concentrated electrolytes with low-polar solvent that could retain unusual functions of original concentrated electrolytes with lower viscosity and higher ionic conductivity.
Jiao, S. et al. Stable cycling of high-voltage lithium metal batteries in ether electrolytes. Nat. Energy 3, 739–746 (2018).
Jeong, S. K. et al. Suppression of dendritic lithium formation by using concentrated electrolyte solutions. Electrochem. Commun. 10, 635–638 (2008). This work applied the concept of concentrated electrolytes to lithium metal anodes to achieve better Coulombic efficiencies and less dendritic deposition.
Qian, J. et al. High rate and stable cycling of lithium metal anode. Nat. Commun. 6, 6362 (2015).
Tatara, R. et al. Solvate ionic liquid, [Li(triglyme)1][NTf2], as electrolyte for rechargeable Li/air battery: discharge depth and reversibility. Chem. Lett. 42, 1053–1055 (2013).
Li, F., Zhang, T., Yamada, Y., Yamada, A. & Zhou, H. Enhanced cycling performance of Li-O2 batteries by the optimized electrolyte concentration of LiTFSA in glymes. Adv. Energy Mater. 3, 532–538 (2013).
He, M. et al. Concentrated electrolyte for the sodium-oxygen battery: solvation structure and improved cycle life. Angew. Chem. Int. Ed. 55, 15310–15314 (2016).
Liu, B. et al. Enhanced cycling stability of rechargeable Li-O2 batteries using high-concentration electrolytes. Adv. Funct. Mater. 26, 605–613 (2016).
Liu, B. et al. Stabilization of Li metal anode in DMSO-based electrolytes via optimization of salt–solvent coordination for Li–O2 batteries. Adv. Energy Mater. 7, 1602605 (2017).
Okuoka, S. et al. A new sealed lithium-peroxide battery with a Co-doped Li2O cathode in a superconcentrated lithium bis(fluorosulfonyl)amide electrolyte. Sci. Rep. 4, 5684 (2014).
Mogensen, R., Brandell, D. & Younesi, R. Solubility of the solid electrolyte interphase (SEI) in sodium ion batteries. ACS Energy Lett. 1, 1173–1178 (2016).
Ribière, P. et al. Investigation on the fire-induced hazards of Li-ion battery cells by fire calorimetry. Energy Environ. Sci. 5, 5271–5280 (2012).
Ping, P. et al. Study of the fire behavior of high-energy lithium-ion batteries with full-scale burning test. J. Power Sources 285, 80–89 (2015).
Wang, X., Yasukawa, E. & Kasuya, S. Nonflammable trimethyl phosphate solvent-containing electrolytes for lithium-ion batteries: I. fundamental properties. J. Electrochem. Soc. 148, A1058–A1065 (2001).
Matsumoto, K. et al. Performance improvement of Li ion battery with non-flammable TMP mixed electrolyte by optimization of lithium salt concentration and SEI preformation technique on graphite anode. J. Electrochem. Soc. 161, A831–A834 (2014).
Zeng, Z. et al. A safer sodium-ion battery based on nonflammable organic phosphate electrolyte. Adv. Sci. 3, 1600066 (2016).
Hess, S., Wohlfahrt-Mehrens, M. & Wachtler, M. Flammability of Li-ion battery electrolytes: flash point and self-extinguishing time measurements. J. Electrochem. Soc. 162, A3084–A3097 (2015).
Zeng, Z. et al. Non-flammable electrolytes with high salt-to-solvent ratios for Li-ion and Li-metal batteries. Nat. Energy 3, 674–681 (2018).
Suo, L. et al. ‘Water-in-salt’ electrolyte enables high-voltage aqueous lithium-ion chemistries. Science 350, 938–943 (2015). This work applied the concept of concentrated electrolytes to an aqueous system to achieve high-voltage aqueous batteries.
Yamada, Y. et al. Hydrate-melt electrolytes for high-energy-density aqueous batteries. Nat. Energy 1, 16129 (2016).
Yang, C. et al. 4.0 V aqueous Li-ion batteries. Joule 1, 122–132 (2017).
Zheng, H., Li, J., Song, X., Liu, G. & Battaglia, V. S. A comprehensive understanding of electrode thickness effects on the electrochemical performances of Li-ion battery cathodes. Electrochim. Acta 71, 258–265 (2012).
Sander, J. S., Erb, R. M., Li, L., Gurijala, A. & Chiang, Y.-M. High-performance battery electrodes via magnetic templating. Nat. Energy 1, 16099 (2016).
Takada, K. et al. Unusual passivation ability of superconcentrated electrolytes toward hard carbon negative electrodes in sodium-ion batteries. ACS Appl. Mater. Interfaces 9, 33802–33809 (2017).
Aihara, Y., Sugimoto, K., Price, W. S. & Hayamizu, K. Ionic conduction and self-diffusion near infinitesimal concentration in lithium salt-organic solvent electrolytes. J. Chem. Phys. 113, 1981–1991 (2000).
Tang, Z. K., Tse, J. S. & Liu, L. M. Unusual Li-ion transfer mechanism in liquid electrolytes: a first-principles study. J. Phys. Chem. Lett. 7, 4795–4801 (2016).
Okoshi, M., Chou, C. P. & Nakai, H. Theoretical analysis of carrier ion diffusion in superconcentrated electrolyte solutions for sodium-ion batteries. J. Phys. Chem. B 122, 2600–2609 (2018).
Borodin, O. et al. Liquid structure with nano-heterogeneity promotes cationic transport in concentrated electrolytes. ACS Nano 11, 10462–10471 (2017).
Ushirogata, K., Sodeyama, K., Futera, Z., Tateyama, Y. & Okuno, Y. Near-shore aggregation mechanism of electrolyte decomposition products to explain solid electrolyte interphase formation. J. Electrochem. Soc. 162, A2670–A2678 (2015).
Jeong, S.-K., Inaba, M., Iriyama, Y., Abe, T. & Ogumi, Z. Electrochemical intercalation of lithium ion within graphite from propylene carbonate solutions. Electrochem. Solid State Lett. 6, A13–A15 (2003). This work discovered unusual behaviour of concentrated electrolytes in lithium-ion batteries.
Yamada, Y. et al. Corrosion prevention mechanism of aluminum metal in superconcentrated electrolytes. ChemElectroChem 2, 1687–1694 (2015).
Alvarado, J. et al. A carbonate-free, sulfone-based electrolyte for high-voltage Li-ion batteries. Mater. Today 21, 341–353 (2018).
Moon, H. et al. Solvent activity in electrolyte solutions controls electrochemical reactions in Li-ion and Li-sulfur batteries. J. Phys. Chem. C 6, 3957–3970 (2015).
Ren, X. et al. Localized high-concentration sulfone electrolytes for high-efficiency lithium-metal batteries. Chem 4, 1877–1892 (2018).
Ueno, K. et al. Li+ solvation and ionic transport in lithium solvate ionic liquids diluted by molecular solvents. J. Phys. Chem. C 120, 15792–15802 (2016).
Chen, S. et al. High-voltage lithium-metal batteries enabled by localized high-concentration electrolytes. Adv. Mater. 1706102, 1706102 (2018).
Doi, T., Shimizu, Y., Hashinokuchi, M. & Inaba, M. Dilution of highly concentrated LiBF4/propylene carbonate electrolyte solution with fluoroalkyl ethers for 5-V LiNi0.5Mn1.5O4 positive electrodes. J. Electrochem. Soc. 164, A6412–A6416 (2017).
Yabuuchi, N., Kubota, K., Dahbi, M. & Komaba, S. Research development on sodium-ion batteries. Chem. Rev. 114, 11636–11682 (2014).
Wu, X., Leonard, D. P. & Ji, X. Emerging non-aqueous potassium-ion batteries: challenges and opportunities. Chem. Mater. 29, 5031–5042 (2017).
Erickson, E. M. et al. Review — development of advanced rechargeable batteries: a continuous challenge in the choice of suitable electrolyte solutions. J. Electrochem. Soc. 162, A2424–A2438 (2015).
Elia, G. A. et al. An overview and future perspectives of aluminum batteries. Adv. Mater. 28, 7564–7579 (2016).
Komaba, S. et al. Electrochemical Na insertion and solid electrolyte interphase for hard-carbon electrodes and application to Na-ion batteries. Adv. Funct. Mater. 21, 3859–3867 (2011).
Ponrouch, A., Marchante, E., Courty, M., Tarascon, J.-M. & Palacín, M. R. In search of an optimized electrolyte for Na-ion batteries. Energy Environ. Sci. 5, 8572–8583 (2012).
Eshetu, G. G. et al. Comprehensive insights into the reactivity of electrolytes based on sodium ions. ChemSusChem 9, 462–471 (2016).
Jian, Z., Luo, W. & Ji, X. Carbon electrodes for K-ion batteries. J. Am. Chem. Soc. 137, 11566–11569 (2015).
Komaba, S., Hasegawa, T., Dahbi, M. & Kubota, K. Potassium intercalation into graphite to realize high-voltage/high-power potassium-ion batteries and potassium-ion capacitors. Electrochem. Commun. 60, 172–175 (2015).
Okoshi, M., Yamada, Y., Komaba, S., Yamada, A. & Nakai, H. Theoretical analysis of interactions between potassium ions and organic electrolyte solvents: a comparison with lithium, sodium, and magnesium ions. J. Electrochem. Soc. 164, A54–A60 (2017).
Aurbach, D. et al. Prototype systems for rechargeable magnesium batteries. Nature 407, 724–727 (2000).
Cheng, Y. et al. Highly active electrolytes for rechargeable Mg batteries based on a [Mg2(μ-Cl)2]2+ cation complex in dimethoxyethane. Phys. Chem. Chem. Phys. 17, 13307–13314 (2015).
Lin, M. C. et al. An ultrafast rechargeable aluminium-ion battery. Nature 520, 325–328 (2015).
Huang, F. et al. Enhancing metallic lithium battery performance by tuning the electrolyte solution structure. J. Mater. Chem. A 6, 1612–1620 (2018).
Chen, F. & Forsyth, M. Elucidation of transport mechanism and enhanced alkali ion transference numbers in mixed alkali metal–organic ionic molten salts. Phys. Chem. Chem. Phys. 18, 19336–19344 (2016).
Ding, M. S., Von Cresce, A. & Xu, K. Conductivity, viscosity, and their correlation of a super-concentrated aqueous electrolyte. J. Phys. Chem. C 121, 2149–2153 (2017).
Sodeyama, K., Yamada, Y., Aikawa, K., Yamada, A. & Tateyama, Y. Sacrificial anion reduction mechanism for electrochemical stability improvement in highly concentrated Li-salt electrolyte. J. Phys. Chem. C 118, 14091–14097 (2014).
Yamada, Y. & Yamada, A. Superconcentrated electrolytes to create new interfacial chemistry in non-aqueous and aqueous rechargeable batteries. Chem. Lett. 46, 1056–1064 (2017).
Suo, L. et al. Fluorine-donating electrolytes enable highly reversible 5-V-class Li metal batteries. Proc. Natl Acad. Sci. USA 115, 1156–1161 (2018).
Lee, J. et al. Ultraconcentrated sodium bis(fluorosulfonyl)imide-based electrolytes for high-performance sodium metal batteries. ACS Appl. Mater. Interfaces 9, 3723–3732 (2017).
Takenaka, N. et al. Microscopic formation mechanism of solid electrolyte interphase film in lithium-ion batteries with highly concentrated electrolyte. J. Phys. Chem. C 122, 2564–2571 (2018).
Peng, Q., Liu, H. & Ye, S. Adsorption of organic carbonate solvents on a carbon surface probed by sum frequency generation (SFG) vibrational spectroscopy. J. Electroanal. Chem. 800, 134–143 (2017).
Leung, K. et al. Using atomic layer deposition to hinder solvent decomposition in lithium ion batteries: first-principles modeling and experimental studies. J. Am. Chem. Soc. 133, 14741–14754 (2011).
Tuckerman, M. E., Marx, D. & Parinello, M. The natue and transport mechanism of hydrated hydroxide ions in aqueous solution. Nature 417, 925–929 (2002).
Marx, D., Tuckerman, M. E., Hutter, J. & Parrinello, M. The nature of the hydrated excess proton in water. Nature 397, 601–604 (1998).
Borodin, O. et al. Modeling insight into battery electrolyte electrochemical stability and interfacial structure. Acc. Chem. Res. 50, 2886–2894 (2017).
Borodin, O. & Smith, G. D. Development of many-body polarizable force fields for Li-battery applications: 2. LiTFSI-doped oligoether, polyether, and carbonate-based electrolytes. J. Phys. Chem. B 110, 6293–6299 (2006).
Kohagen, M. et al. Performance of quantum chemically derived charges and persistence of ion cages in ionic liquids. a molecular dynamics simulations study of 1-n-butyl-3-methylimidazolium bromide. J. Phys. Chem. B 115, 693–702 (2011).
Takenaka, N., Suzuki, Y., Sakai, H. & Nagaoka, M. On electrolyte-dependent formation of solid electrolyte interphase film in lithium-ion batteries: strong sensitivity to small structural difference of electrolyte molecules. J. Phys. Chem. C 118, 10874–10882 (2014).
Cuisinier, M. et al. Unique behaviour of nonsolvents for polysulphides in lithium–sulphur batteries. Energy Environ. Sci. 7, 2697–2705 (2014).
Moon, H. et al. Mechanism of Li ion desolvation at the interface of graphite electrode and glyme–Li salt solvate ionic liquids. J. Phys. Chem. B 118, 20246–20256 (2014).
Kim, H. et al. In situ formation of protective coatings on sulfur cathodes in lithium batteries with LiFSI-based organic electrolytes. Adv. Energy Mater. 5, 1401792 (2015).
Doi, T., Masuhara, R., Hashinokuchi, M., Shimizu, Y. & Inaba, M. Concentrated LiPF6/PC electrolyte solutions for 5-V LiNi0.5Mn1.5O4 positive electrode in lithium-ion batteries. Electrochim. Acta 209, 219–224 (2016).
Suo, L. et al. Advanced high-voltage aqueous lithium-ion battery enabled by ‘water-in-bisalt’ electrolyte. Angew. Chem. Int. Ed. 55, 7136–7141 (2016).
Lu, D. et al. Formation of reversible solid electrolyte interface on graphite surface from concentrated electrolytes. Nano Lett. 17, 1602–1609 (2017).
Shiga, T., Kato, Y., Kondo, H. & Okuda, C. Self-extinguishing electrolytes using fluorinated alkyl phosphates for lithium batteries. J. Mater. Chem. A 5, 5156–5162 (2017).
Yang, C. et al. Unique aqueous Li-ion/sulfur chemistry with high energy density and reversibility. Proc. Natl Acad. Sci. USA 114, 6197–6202 (2017).
Fan, X. et al. Highly fluorinated interphases enable high-voltage Li-metal batteries. Chem 4, 174–185 (2018).
Zheng, J. et al. Extremely stable sodium metal batteries enabled by localized high-concentration electrolytes. ACS Energy Lett. 3, 315–321 (2018).
Wang, F. et al. Highly reversible zinc metal anode for aqueous batteries. Nat. Mater. 17, 543–549 (2018).
Chen, S. et al. High-efficiency lithium metal batteries with fire-retardant electrolytes. Joule 2, 1548–1558 (2018).
Tamura, T. et al. New glyme-cyclic imide lithium salt complexes as thermally stable electrolytes for lithium batteries. J. Power Sources 195, 6095–6100 (2010).
Yamada, Y., Takazawa, Y., Miyazaki, K. & Abe, T. Electrochemical lithium intercalation into graphite in dimethyl sulfoxide-based electrolytes: effect of solvation structure of lithium ion. J. Phys. Chem. C 114, 11680–11685 (2010).
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Yamada, Y., Wang, J., Ko, S. et al. Advances and issues in developing salt-concentrated battery electrolytes. Nat Energy 4, 269–280 (2019). https://doi.org/10.1038/s41560-019-0336-z
A high-energy-density and long-life initial-anode-free lithium battery enabled by a Li2O sacrificial agent
Nature Energy (2021)
Nature Energy (2021)
Highly efficient lithium utilization in lithium metal full-cell by simulated missile guidance and confinement systems
Science China Materials (2021)
Nature Communications (2020)
Theoretically predicting the feasibility of highly-fluorinated ethers as promising diluents for non-flammable concentrated electrolytes
Scientific Reports (2020)