Coregulation of Li/Li+ Spatial Distribution by Electric Field Gradient with Homogenized Li-Ion Flux for Dendrite-Free Li Metal Anodes.

Abstract

Lithium (Li) metal batteries are highly sought after for their exceptional energy density. However, their practical implementation is impeded by the formation of dendrites and significant volume fluctuations in Li, which stem from the uneven distribution of Li-ions and uncontrolled deposition of Li on the current collector. Here, an amino-functionalized reduced graphene oxide covered with polyacrylonitrile (PrGN) film with an electric field gradient structure is prepared to deal with such difficulties. This novel current collector serves to stabilize Li-metal anodes by regulating Li-ion flux through vertically aligned channels formed by porous polyacrylonitrile (PAN). Moreover, the amino-functionalized reduced graphene oxide (rGN) acts as a three-dimensional (3D) host, reducing nucleation overpotential and accommodating volume expansion during cycling. The combination of the insulating PAN and conducting rGN creates an electric field gradient that promotes a bottom-up mode of Li electrodeposition and safeguards the anode from interfacial parasitic reactions. Consequently, the electrodes exhibit exceptional cycle life with stable voltage profiles and minimal hysteresis under high current densities and large areal capacities.