Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Aqueous electrolyte design for super-stable 2.5 V LiMn2O4 || Li4Ti5O12 pouch cells



To compete with commercial organic electrolytes, aqueous electrolytes beyond water-in-salt electrolytes with a lower salt concentration of <5.0 m (mol kgsolvent–1) and wider electrochemical stability window of >3.0 V are urgently needed. Here we report a 4.5 m lithium bis(trifluoromethanesulfonyl) imide (LiTFSI)–KOH–CO(NH2)2–H2O non-flammable ternary eutectic electrolyte that expands the electrochemical stability window to >3.3 V by forming a robust solid–electrolyte interphase. The ternary eutectic electrolyte enables Li1.5Mn2O4 || Li4Ti5O12 pouch cells to achieve a high average Coulombic efficiency of 99.96% and capacity retention of 92% after 470 cycles at an areal capacity of 2.5 mAh cm–2, a low positive/negative capacity ratio of 1.14 and a lean electrolyte (3 g Ah–1). The Li loss due to the solid–electrolyte interphase formation in the initial charge/discharge cycles is compensated by an excess 0.5 Li in the Li1.5Mn2O4 cathode, which converts the Li1.5Mn2O4 || Li4Ti5O12 cell into LiMn2O4 || Li4Ti5O12 after solid–electrolyte interphase formation. The 2.5 V aqueous Li1.5Mn2O4 || Li4Ti5O12 pouch cells with practical settings demonstrate a promising approach towards safe, low-cost and high-energy aqueous Li-ion batteries.

Your institute does not have access to this article

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Spectrum analysis of intermolecular interaction.
Fig. 2: The electrochemical stability window of aqueous electrolytes.
Fig. 3: Structural and chemical analysis of SEI layer.
Fig. 4: Electrochemical performances of 2.5 V LiMn2O4 || Li4Ti5O12 and 2.6 V LiVPO4F || Li4Ti5O12 full cells at an areal capacity of 1.5 mAh cm–2.
Fig. 5: Electrochemical performances of 2.5 V LiMn2O4 || Li4Ti5O12 pouch cells.

Data availability

The data supporting the findings of this study are available within the article and its Supplementary Information files.


  1. Suo, L. et al. “Water-in-salt” electrolyte enables high-voltage aqueous lithium-ion chemistries. Science 350, 938–943 (2015).

    Article  Google Scholar 

  2. Ueno, K. et al. Glyme–lithium salt equimolar molten mixtures: concentrated solutions or solvate ionic liquids? J. Phys. Chem. B 116, 11323–11331 (2012).

    Article  Google Scholar 

  3. Wang, J. et al. Superconcentrated electrolytes for a high-voltage lithium-ion battery. Nat. Commun. 7, 12032 (2016).

    Article  Google Scholar 

  4. Borodin, O., Self, J., Persson, K. A., Wang, C. & Xu, K. Uncharted waters: super-concentrated electrolytes. Joule 4, 69–100 (2020).

    Article  Google Scholar 

  5. Jiao, S. et al. Stable cycling of high-voltage lithium metal batteries in ether electrolytes. Nat. Energy 3, 739–746 (2018).

    Article  Google Scholar 

  6. Cao, Z., Hashinokuchi, M., Doi, T. & Inaba, M. Improved cycle performance of LiNi0.8Co0.1Mn0.1O2 positive electrode material in highly concentrated LiBF4/DMC. J. Electrochem. Soc. 166, A82–A88 (2019).

    Article  Google Scholar 

  7. Chen, S. et al. High-voltage lithium-metal batteries enabled by localized high-concentration electrolytes. Adv. Mater. 30, 1706102 (2018).

    Article  Google Scholar 

  8. Cao, X. et al. Monolithic solid–electrolyte interphases formed in fluorinated orthoformate-based electrolytes minimize Li depletion and pulverization. Nat. Energy 4, 796–805 (2019).

    Article  Google Scholar 

  9. Fan, X. et al. Non-flammable electrolyte enables Li-metal batteries with aggressive cathode chemistries. Nat. Nanotechnol. 13, 715–722 (2018).

    Article  Google Scholar 

  10. Yamada, Y. et al. Hydrate-melt electrolytes for high-energy-density aqueous batteries. Nat. Energy 1, 16129 (2016).

    Article  Google Scholar 

  11. 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).

    Article  Google Scholar 

  12. Wang, F. et al. Spinel LiNi0.5Mn1.5O4 cathode for high-energy aqueous lithium-ion batteries. Adv. Energy Mater. 7, 1600922 (2017).

    Article  Google Scholar 

  13. Lukatskaya, M. R. et al. Concentrated mixed cation acetate “water-in-salt” solutions as green and low-cost high voltage electrolytes for aqueous batteries. Energy Environ. Sci. 11, 2876–2883 (2018).

    Article  Google Scholar 

  14. Ko, S. et al. Lithium-salt monohydrate melt: a stable electrolyte for aqueous lithium-ion batteries. Electrochem. Commun. 104, 106488 (2019).

    Article  Google Scholar 

  15. Chen, L. et al. A 63 m superconcentrated aqueous electrolyte for high-energy Li-ion batteries. ACS Energy Lett. 5, 968–974 (2020).

    Article  Google Scholar 

  16. Droguet, L., Grimaud, A., Fontaine, O. & Tarascon, J. M. Water-in-salt electrolyte (WiSE) for aqueous batteries: a long way to practicality. Adv. Energy Mater. 10, 2002440 (2020).

    Article  Google Scholar 

  17. Wang, F. et al. Hybrid aqueous/non-aqueous electrolyte for safe and high-energy Li-ion batteries. Joule 2, 927–937 (2018).

    Article  Google Scholar 

  18. Chen, J. et al. Improving electrochemical stability and low-temperature performance with water/acetonitrile hybrid electrolytes. Adv. Energy Mater. 10, 1902654 (2020).

    Article  Google Scholar 

  19. Yang, C. et al. 4.0 V aqueous Li-ion batteries. Joule 1, 122–132 (2017).

    Article  Google Scholar 

  20. He, X. et al. Fluorine-free water-in-ionomer electrolytes for sustainable lithium-ion batteries. Nat. Commun. 9, 5320 (2018).

  21. Xie, J., Liang, Z. & Lu, Y.-C. Molecular crowding electrolytes for high-voltage aqueous batteries. Nat. Mater. 19, 1006–1011 (2020).

  22. Dubouis, N. et al. The role of the hydrogen evolution reaction in the solid–electrolyte interphase formation mechanism for “water-in-salt” electrolytes. Energy Environ. Sci. 11, 3491–3499 (2018).

    Article  Google Scholar 

  23. Cordeiro, J. M. M. & Freitas, L. C. G. Study of water and dimethylformamide interaction by computer simulation. Z. Naturforsch. A 54, 110–116 (1999).

    Article  Google Scholar 

  24. Qiu, H. et al. Zinc anode-compatible in-situ solid electrolyte interphase via cation solvation modulation. Nat. Commun. 10, 5374 (2019).

  25. Zhao, J. et al. “Water-in-deep eutectic solvent” electrolytes enable zinc metal anodes for rechargeable aqueous batteries. Nano Energy 57, 625–634 (2019).

    Article  Google Scholar 

  26. Hu, Z. et al. Nonflammable nitrile deep eutectic electrolyte enables high-voltage lithium metal batteries. Chem. Mater. 8, 3405–3413 (2020).

    Article  Google Scholar 

  27. Rousseau, B., Alsenoy, C. V., Keuleers, R. & Desseyn, H. Solids modeled by ab-initio crystal field methods. Part 17. Study of the structure and vibrational spectrum of urea in the gas phase and in its P4̄21m crystal phase. J. Phys. Chem. A 102, 6540–6548 (1998).

    Article  Google Scholar 

  28. Araujo, C. et al. Inelastic neutron scattering study of reline: shedding light on the hydrogen bonding network of deep eutectic solvents. Phys. Chem. Chem. Phys. 19, 17998–18009 (2017).

    Article  Google Scholar 

  29. Keuleers, R., Desseyn, H., Rousseau, B. & Alsenoy, C. V. Vibrational analysis of urea. J. Phys. Chem. A 103, 4621–4630 (1999).

    Article  Google Scholar 

  30. Finer, E., Franks, F. & Tait, M. Nuclear magnetic resonance studies of aqueous urea solutions. J. Am. Chem. Soc. 94, 4424–4429 (1972).

    Article  Google Scholar 

  31. Sim, L., Yahya, R. & Arof, A. Infrared studies of polyacrylonitrile-based polymer electrolytes incorporated with lithium bis (trifluoromethane) sulfonimide and urea as deep eutectic solvent. Opt. Mater. 56, 140–144 (2016).

    Article  Google Scholar 

  32. Zhu, B., Liang, Z. & Zou, R. Designing advanced catalysts for energy conversion based on urea oxidation reaction. Small 16, 1906133 (2020).

    Article  Google Scholar 

  33. Xu, J. et al. Conductive carbon nitride for excellent energy storage. Adv. Mater. 29, 1701674 (2017).

    Article  Google Scholar 

  34. Beamson, G. & Briggs, D. High Resolution XPS of Organic Polymers, the Scienta ESCA300 Database (Wiley, 1992).

  35. Shaw, W. H. & Bordeaux, J. J. The decomposition of urea in aqueous media. J. Am. Chem. Soc. 77, 4729–4733 (1955).

    Article  Google Scholar 

  36. Hou, Z. et al. Formation of solid–electrolyte interfaces in aqueous electrolytes by altering cation-solvation shell structure. Adv. Energy Mater. 10, 1903665 (2020).

    Article  Google Scholar 

  37. Violante de Paz Ba´ñez, M., Aznar Moreno, J. A. & Galbis, J. A. Versatile sugar derivatives for the synthesis of potential degradable hydrophilic-hydrophobic polyurethanes and polyureas. J. Carbohydr. Chem. 27, 120–140 (2008).

    Article  Google Scholar 

  38. Chen, J. et al. Electrolyte design for LiF-rich solid–electrolyte interfaces to enable high-performance microsized alloy anodes for batteries. Nat. Energy 5, 386–397 (2020).

    Article  Google Scholar 

  39. Smith, A., Burns, J. C., Zhao, X., Xiong, D. & Dahn, J. A high precision coulometry study of the SEI growth in Li/graphite cells. J. Electrochem. Soc. 158, A447–A452 (2011).

    Article  Google Scholar 

  40. Diaz‐Lopez, M. et al. Li2O: Li–Mn–O disordered rock-salt nanocomposites as cathode prelithiation additives for high-energy density Li-ion batteries. Adv. Energy Mater. 10, 1902788 (2020).

    Article  Google Scholar 

  41. Betz, J. et al. Theoretical versus practical energy: a plea for more transparency in the energy calculation of different rechargeable battery systems. Adv. Energy Mater. 9, 1803170 (2019).

    Article  Google Scholar 

  42. Chao, D. et al. Roadmap for advanced aqueous batteries: from design of materials to applications. Sci. Adv. 6, eaba4098 (2020).

    Article  Google Scholar 

  43. Manalastas, W. Jr et al. Water in rechargeable multivalent-ion batteries: an electrochemical Pandora’s box. ChemSusChem 12, 379–396 (2019).

    Article  Google Scholar 

Download references


This work was financially supported by the US Department of Energy ARPA-E grant DEAR0000389.

Author information

Authors and Affiliations



J.X. and C.W. conceived the idea for the project. J.X., J.Z. and C.Y. prepared the materials and performed the electrochemical experiments. X.J. conducted the quantum chemistry calculations and molecular dynamics simulations. J.X., P.W. and S.L. conducted the characterizations. K.L. and P.K. completed the differential scanning calorimetry tests. F.C. performed the NMR measurements. All the authors discussed the results, analysed the data and draughted the manuscript.

Corresponding author

Correspondence to Chunsheng Wang.

Ethics declarations

Competing interests

J.X., X.J. and C.H. are inventors on the US patent application (application number 2021-158-1) filed by the University of Maryland regarding the electrolytes described in this Article.

Peer review

Peer review information

Nature Energy thanks Maria Lukatskaya and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Notes 1–7, Tables 1–6 and Figs. 1–33.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Xu, J., Ji, X., Zhang, J. et al. Aqueous electrolyte design for super-stable 2.5 V LiMn2O4 || Li4Ti5O12 pouch cells. Nat Energy 7, 186–193 (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing