Spatially Controlled Lithium Deposition on Silver-Nanocrystals-Decorated TiO_2 Nanotube Arrays Enabling Ultrastable Lithium Metal Anode

摘要

3D scaffolds and heterogeneous seeds are two effective ways to guide Li deposition and suppress Li dendrite growth. Herein, 3D TiO2 nanotube (TNT) arrays decorated using ultrafine silver nanocrystals (7-10 nm) through cathodic reduction deposition are first demonstrated as a confined space host for lithium metal deposition. First, TiO2 possesses intrinsic lithium affinity with large Li absorption energy, which facilitates Li capture. Then, ultrafine silver nanocrystals decoration allows the uniform and selective nucleation in nanoscale without a nucleation barrier, leading to the extraordinary formation of lithium metal importing into 3D nanotube arrays. As a result, Li metal anode deposited on such a binary architecture (TNT-Ag-Li) delivers a high Coulomb efficiency at around 99.4% even after 300 cycles with a capacity of 2 mA h cm(-2). Remarkably, TNT-Ag-Li exhibits ultralow overpotential of 4 mV and long-term cycling life over 2500 h with a capacity of 2 mAh cm(-2) in Li symmetric cells. Moreover, the full battery with 3D spaced Li nanotubes anode and LiFeO4 cathode exhibits a stable and high capacity of 115 mA h g(-1) at 5 C and an excellent Coulombic efficiency of approximate to 100% over 500 cycles.