Lithium metal is considered as one of the most promising anode candidates for high-energy batteries [1-3]. However, safety concerns induced by the formation of Li dendrites largely hinder the practical application of lithium-metal batteries [4]. It is anticipated that the use of non-flammable inorganic solid-state electrolytes can resolve these safety issues [5], but solid ceramic electrolytes generally suffer from poor physical contact with the electrode and poor electro-/chemical stability at the electrolyte|electrode interface [6].

Herein, we report on a thin and flexible hybrid electrolyte composed of NASICON-type Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP), a polymer binder, and a small amount of an ionic liquid-based electrolyte. To reinforce the interfacial stability between LATP and Li, we coat an ultrathin polysiloxane-based single-ion conducting polymer (PSiO) on the Li metal surface via a simple dip-coating method. The implementation of PSiO-coated Li (PSiO@Li) in symmetric PSiO@Li||PSiO@Li cells enables a substantial extension of the cycle life, yielding >2,000 h of stable lithium stripping-plating. The full-cells comprising PSiO@Li as the negative electrode, LiNi_0.88Co_0.09Mn_0.03O₂ (NCM₈₈) as the positive electrode active material, and the aforementioned hybrid electrolyte exhibit substantially enhanced rate capability at high dis-/charge rates above 0.5C and greatly prolonged cycle life at 1C. The superior performance achieved herein is mainly attributed to: (1) the prevented direct contact between LATP and Li, thus avoiding the reduction of LATP and the formation of mixed ion-electron conducting interphases; (2) the regulated Li⁺ flux at the electrode|electrolyte interface, ensuring homogeneous Li⁺ stripping-plating; and (3) the promoted intimate contact between PSiO and Li via the formation of Si−O−Li bonds.

References

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[2] B. Horstmann, J. Shi, R. Amine, M. Werres, X. He, H. Jia, F. Hausen, I. Cekic-Laskovic, S. Wiemers-Meyer, J. Lopez, D. Galvez-Aranda, F. Baakes, D. Bresser, C.-C. Su, Y. Xu, W. Xu, P. Jakes, R.-A. Eichel, E. Figgemeier, U. Krewer, J.M. Seminario, P.B. Balbuena, C. Wang, S. Passerini, Y. Shao-Horn, M. Winter, K. Amine, R. Kostecki, A. Latz, Energy Environ. Sci., 14 (2021) 5289-5314.

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