Reinforcing the Li|Li_1.3Al_0.3Ti_1.7(PO₄)₃ Interfacial Stability By an Ultrathin Multifunctional Polysiloxane-Based Single-Ion Conducting Polymer

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 Li1.3Al0.3Ti1.7(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, LiNi0.88Co0.09Mn0.03O2 (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 [1] T. Li, X.-Q. Zhang, P. Shi, Q. Zhang, Joule, 3 (2019) 2647-2661. [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. [3] S. Wang, P. Xiong, J. Zhang, G. Wang, Energy Storage Materials, 29 (2020) 310-331. [4] Z. Yu, Y. Cui, Z. Bao, Cell Rep. Phy. Sci., 1 (2020) 100119. [5] S. Xin, Y. You, S. Wang, H.-C. Gao, Y.-X. Yin, Y.-G. Guo, ACS Energy Lett., 2 (2017) 1385-1394. [6] A. Banerjee, X. Wang, C. Fang, E.A. Wu, Y.S. Meng, Chem. Rev., 120 (2020) 6878-6933.