An Anode-Free Potassium-Metal Battery Enabled by a Directly Grown Graphene-Modulated Aluminum Current Collector

Potassium (K)-metal batteries have emerged as a promising energy-storage device owing to abundant K resources. An anode-free architecture that bypasses the need for anode host materials can deliver an elevated energy density. However, the poor efficiency of K plating/stripping on potassiophobic anode current collectors results in rapid K inventory loss and a short cycle life. Herein, commercial Al foils are decorated with an ultrathin graphene-modified layer (Al@G) through roll-to-roll plasma-enhanced chemical vapor deposition. By harnessing strong adhesion (10.52 N m(-1)) and a high surface energy (66.6 mJ m(-2)), the designed Al@G structure ensures a highly smooth and ordered K plating/stripping process. Consequently, during K-metal plating/stripping, Al@G can operate at a current density of up to 4.0 mA cm(-2) and cyclic capacity of up to 4.0 mAh cm(-2), with an ultralong lifespan of up to 1000 h at 0.5 mA cm(-2) and stable cycling of up to 750 h under periodic current fluctuations of 0.1-2.0 mA cm(-2). In addition, a novel anode-free K-metal full-cell prototype enabled by Al@G anode current collectors is constructed, demonstrating ameliorative cyclic stability.

Automated summary

This article presents an anode-free structure for potassium metal batteries, which enhances the plating/stripping efficiency of potassium metal by adding an ultrathin graphene-modified layer on commercial aluminum foils. The designed structure demonstrates high stability and long lifespan under high current density and cyclic capacity, as well as stable cycling performance under fluctuating current.