Cobalt-catalyzed organic nano carbon source for hybrid hard carbon/graphite nanoribbon anode in high-potential potassium-ion batteries

Abstract

Potassium-ion batteries (PIBs) have attracted intense interest because of the abundance and low cost of potassium carbonate as a raw material. Hard carbon has shown high potential as the anode in PIBs at high fluorosulfonimide-based electrolytes concentration due to large d-space giving the dominated capacitive-controlled process. However, high discharge slope and high concentration electrolytes are harmful to the cathode and hinder the hard carbon-based PIBs in practice. Graphite nanoribbons can bridge the hard carbon domain for balancing the capacitive and intercalation-controlled process due to the high conductivity and length/width ratio. However, the bottom-up synthesis of graphite nanoribbon-based heterostructure is a still huge challenge. Herein, hard carbon domains interconnected by graphite nanoribbon (named HC-GNR) are obtained via a one-step calcination of dispersed Co salts Organic Nano Carbon Source (ONCS). By full characterization of HC-GNR with different Co content, the growth mechanism of graphite nanoribbons is proposed as three steps: Absorption of graphene nanosheets transformed by ONCS, Seaming, and desorption to the hard carbon domain. HC-GNR-L shows an ultralow cobalt content of 9.02 wt.% characterized and calculated by TGA. It is assembled as the anode in a half-cell and exhibits a stable specific capacity of 104 mAh g⁻¹ at a current density of 500 mA g⁻¹ after 500 charge–discharge cycles in PIBs at a low concentration electrolyte of 0.8 M KPF₆. Finally, a bottom-up synthesis paradigm of graphite nanoribbon first has been introduced, which will prompt the graphite nanoribbon in the application of electronic device industrial and other large-scale industrial fields.