Highly Potassiophilic Graphdiyne Skeletons Decorated with Cu Quantum Dots Enable Dendrite-Free Potassium-Metal Anodes.

Abstract

Employing an Al foil current collector at the potassium anode side is an ideal choice to entail low-cost and high-energy potassium-metal batteries (PMBs). Nevertheless, the poor affinity between the potassium and the planar Al can cause uneven K plating/stripping and, hence, an undermined anode performance, which remains a significant challenge to be addressed. Herein, a nitrogen-doped carbon@graphdiyne (NC@GDY)-modified Al current collector affording potassiophilic properties is proposed, which simultaneously suppresses the dendrite growth and prolongs the lifespan of K anodes. The thin and light modification layer (7µm thick, with a mass loading of 500µg cm-2 ) is fabricated by directly growing GDY nanosheets interspersed with Cu quantum dots on NC polyhedron templates. As a result, symmetric cell tests reveal that the K@NC@GDY-Al electrode exhibits an unprecedented cycle life of over 2400 h at a 40% depth of discharge. Even at an 80% depth of discharge, the cell can still sustain for 850 h. When paired with a potassium Prussian blue cathode, the thus-assembled full cell demonstrates comparable capacity and rate performance with state-of-the-art PMBs.