LLZO@EmimFSI@PEO derived hybrid solid electrolyte for high-energy lithium metal batteries

ABSTRACT

Although all-solid-state batteries have good safety and high energy density, they still need to explore high performance solid-state electrolytes to achieve high ionic conductivity, wide electrochemical window and excellent mechanical properties. In this work, we designed a hybrid solid electrolyte to solve these problems via mixing PEO, ionic liquid EmimFSI (1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide), LLZO (Li_6.5Mg_0.05La₃Zr_1.6Ta_0.4O₁₂) and lithium salt, which aimed at suppression of PEO crystallization and employed to improve the mechanical and electrochemical stability. Accordingly, the LLZO@EmimFSI@PEO derived hybrid solid electrolyte provides an ionic conductivity of 1.0×10^-4 S cm^-1 at 40^oC and electrochemical stability window above 5.0 V vs. Li/Li⁺. Furthermore, the symmetric cell of Li/hybrid solid electrolyte/Li exhibits flat voltage profiles and stable lithium plating/stripping process, a solid-state battery based on the hybrid solid electrolyte combined with high-energy lithium metal anode and NCM622 (LiNi_0.6Co_0.2Mn_0.2O₂) cathode was also demonstrated.

KEYWORDS:

• Hybrid solid electrolyte
• poly(ethylene oxide)
• garnet
• ionic liquid
• lithium metal

Acknowledgments

The authors gratefully acknowledge financial support from the National Natural Science Foundation of China (No. 51702030, No. 11632004, and No. U1864208), and the Key Program for International Science and Technology Cooperation Projects of the Chinese Ministry of Science and Technology (No. 2016YFE0125900).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51702030, 11632004, U1864208];Key Program for International Science and Technology Cooperation Projects of the Chinese Ministry of Science and Technology [2016YFE0125900].