Chemically-Engineered Host Materials Enabling Safe Sodium Metal Anodes

Abstract

As an anode material, sodium (Na) metal is the most promising alternative for lithium for the next‐generation energy storage systems. Nevertheless, its practical implementation is impeded by the huge volume change and severe Na metal dendrite growth during electrochemical stripping/plating. Herein, the employment of chemically-engineered porous copper (Cu) and titanium carbide (Ti3C2) MXene as stable host for metallic Na anode is presented. By treating the commercial Cu foam through a facile and cost‐effective method, a composite matrix consists of cylindrical core–shell skeleton is achieved, facilitating uniform impregnation and confinement of Na within the matrix pores promoted by the chemical interaction between Na and the matrix. While by treating Ti3C2 via a facile cetyltrimethylammonium bromide prepillaring followed by subsequent Tin cation (Sn2+) pillaring, a Sn2+ pillared Ti3C2 MXene matrix is obtained, guiding the Na nucleation/growth within the matrix interlayer space and contributing to uniform Na deposition facilitated by the chemical interaction between Na and Sn-based nanocomplexes encapsulated within the MXene layers. The unique characteristic of the chemically-engineered host materials can well accommodate hostless Na+, suppressing the volume change and mossy/dendritic Na growth during cycling. A stable Na cycling behavior is demonstrated in carbonate electrolyte without any additives at a high capacity up to 3 mAh/cm2 with a current density up to 2 mA/cm2. While in ether electrolyte, a stable Na performance at a high capacity up to 5 mAh/cm2 along with a high current density up to 10 mA/cm2 is achieved. Furthermore, electrochemical measurements of a full cell made of the Na composite matrix anodes clearly reveal the superior performance over that using bare Na metal. We believe that our approach provides facile approaches to the fabrication of stable Na metal anodes for high‐energy Na‐based batteries, and could be a viable strategy for other metallic anode systems.[1,2] Reference： [1] C.Wang, H. Wang, E. Matios, X. Hu, W. Li, Adv. Funct. Mater, 2018, 28, 1802282. [2] J. Luo, † C. Wang, † H. Wang, X. Hu, E. Matios, X. Lu, W. Zhang, X. Tao, W. Li, Adv. Funct. Mater, 2018, 1805946. Figure 1