High Capacity, Dendrite-Free Growth, and Minimum Volume Change Na Metal Anode

Na metal anode attracts increasing attention as a promising candidate for Na metal batteries (NMBs) due to the high specific capacity and low poten-tial. However, similar to issues faced with the use of Li metal anode, crucial problems for metallic Na anode remain, including serious moss-like and den-dritic Na growth, unstable solid electrolyte interphase formation, and large infinite volume changes. Here, the rational design of carbon paper (CP) with N-doped carbon nanotubes (NCNTs) as a 3D host to obtain Na@CP-NCNTs composites electrodes for NMBs is demonstrated. In this design, 3D carbon paper plays a role as a skeleton for Na metal anode while vertical N-doped carbon nanotubes can effectively decrease the contact angle between CP and liquid metal Na, which is termed as being “Na-philic.” In addition, the cross-conductive network characteristic of CP and NCNTs can decrease the effective local current density, resulting in uniform Na nucleation. Therefore, the as-prepared Na@CP-NCNT exhibits stable electrochemical plating/strip-ping performance in symmetrical cells even when using a high capacity of 3 mAh cm−2 at high current density. Furthermore, the 3D skeleton structure is observed to be intact following electrochemical cycling with minimum volume change and is dendrite-free in nature