Gradient-Distributed Nucleation Seeds on Conductive Host for a Dendrite-Free and High-Rate Lithium Metal Anode.

Abstract

Much attention is paid to metal lithium as a hopeful negative material for reversible batteries with a high specific capacity. Although applying 3D hosts can relieve the dendrite growth to some extent, gradient-distributed lithium ion in 3D uniform hosts still induces uncontrolled lithium dendrites growth, especially at high lithium capacity and high current density. Herein, a 3D conductive carbon nanofiber framework with gradient-distributed ZnO particles as nucleation seeds (G-CNF) to regulate lithium deposition is proposed. Based on such a unique structure, the G-CNF electrode exhibits a high average Coulombic efficiency (CE) of 98.1% for 700 cycles at 0.5 mA cm-2 . Even at 5 mA cm-2 , the G-CNF electrode performs a stable cycling process and high CE of 96.0% for over 200 cycles. When the lithium-deposited G-CNF (G-CNF-Li) anode is applied in a full cell with a commercial LiFePO4 cathode, it exhibits a stable capacity of 115 mAh g-1 and high retention of 95.7% after 300 cycles. Through inducing the gradient-distributed nucleation seeds to counter the existing Li-ion concentration polarization, a uniform and stable lithium deposition process in the 3D host is achieved even under the condition of high current density.