Green and tunable fabrication of graphene-like N-doped carbon on a 3D metal substrate as a binder-free anode for high-performance potassium-ion batteries

Abstract

Porous carbon materials have a broad range of potential applications, such as in electrochemical energy storage, filtration, catalysis, sensors, hydrogen storage, automobile exhaust treatment and so on. In this work, morphology evolution of metal–organic frameworks on a 3D metal substrate is explored via a simple binary-solvent method. With this rationally designed precursor, a graphene-like N-doped hierarchical porous carbon array on a 3D metal substrate (NPC/Cu) is obtained by a green and one-step vacuum de-metal assisted carbonization process. In situ-produced low boiling-point zinc elements can be evaporated and recycled during this process. The unique architecture where an N-doped porous carbon array is grown on a 3D metal substrate favors the graphitization degree and areal capacities of carbon anodes. When NPC/Cu is applied as a self-standing and binder-free anode for potassium-ion batteries (KIBs) in various electrolytes, an eminent electrochemical performance with a high reversible capacity of 315 mA h g⁻¹ at 50 mA g⁻¹ after 500 cycles, a superior rate performance of 120 mA h g⁻¹ at 21C, and a relatively stable capacity of 129 mA h g⁻¹ at 2000 mA g⁻¹ after 20 000 cycles (corresponding to a capacity decay of only 0.0034% per cycle) can be obtained in a 5 M concentrated ether electrolyte. Furthermore, the superior electrochemical performance, outperforming that of most of the reported carbonaceous anodes for KIBs, can be attributed to the potassium storage mechanism dominated by capacitive-controlled behavior, proven by quantitative kinetics analysis. This work can shed some light on searching for carbon-based materials for KIBs and offer new insight to construct porous materials.