Metal oxide nanoparticles induced step-edge nucleation of stable Li metal anode working under an ultrahigh current density of 15 mA cm−2

Abstract

Lithium (Li) metal has been regarded as promising candidate anode to upgrade the energy density of Li secondary batteries. However, uncontrollable formation of Li dendrite, serious volumetric change, undesirable side reaction and poor mechanical properties of solid electrolyte interphase (SEI) layer impede the commercialization of this technology. By ex-situ observing the initial Li deposition process and conducting electrochemical test, we firstly confirm the prior nucleation behavior of Li metal at the step edge area. We thus employ a balsa wood derived porous carbon matrix as Li host and metal oxide nanoparticles are introduced to increase the nanoscale step amounts for Li nucleation. Hence, the Li nucleation overpotential is reduced and Li can be well accommodated within carbon matrix. Moreover, this step-edge-guided effect could promise the Li striping/plating to happen mainly around the steps area within channels, achieving a dendrite-free anode. Consequently, the modified Li anode is capable of working under an ultrahigh current density of 15mAcm−2 with a Coulombic efficiency of ~ 96% and exhibit lower nucleation overpotential, more satisfactory cycling stability. And when in pair with commercial LiCoO2 cathode, it shows better rate performance and higher capacity compared with bare Li foil.