Lithiophilic amide-functionalized carbon nanotube skeleton for dendrite-free lithium metal anodes

Abstract

Despite numerous efforts to stabilize lithium (Li) metal anodes and suppress dendrite growth, achieving stable Li plating/stripping with long cycle life remains a critical challenge because of a combination of complex degradation modes including nonuniform Li nucleation, huge volume change and uncontrollable side reaction between Li metal and electrolyte. Herein, a free-standing carbon nanotube film functionalized with lithiophilic amide-containing functional groups (Af-CNT) is designed to regulate Li nucleation uniformly and prevent dendrite growth. Owing to the strong interaction between Li/amide and low nucleation overpotential rendered by the lithiophilic functional groups, Li is preferentially deposited along the nanotubes or into the cavities, resulting in a smooth Li deposition morphology. Furthermore, the highly conductive and porous carbon framework can lower local current density for Li plating/stripping and then homogenize the Li deposition. As a result, the Af-CNT electrode enables an ultralow overpotential of ~ 14 mV accompanied with a high Coulombic efficiency (CE) of 97.8% over 300 cycles in a Li||Af-CNT half-cell and realizes a dendrite-free deposition and long-term stable cycling for 1800 h. In full cell configurations with LiFePO4 (LFP) cathode, the Af-CNT@Li anode exhibits excellent cycle stability and low polarization.