Chemical cross-linking and mechanically reinforced carbon network constructed by graphene boosts potassium ion storage

Carbon-based electrodes of potassium-ion batteries are of great research interest ascribed to their low cost and environmentally friendly distinctions. However, traditional carbon materials usually exhibit weak mechanical properties and incomplete crosslinking, resulting in poor stability and electrochemical performance. Herein, we report a new strategy for modifying reduced graphene oxide into a uniform few-layer structure through a sol–gel method combined with acid etching treatment. The obtained chemical cross-linking and mechanically reinforced carbon network constructed by graphene (CNCG) demonstrates excellent electrochemical and mechanical properties. Adopted as a free-standing anode (~ 7 mg·cm⁻²) for potassium ion battery, the as-achieved CNCG delivers a high reversible specific capacity of 317.7 mAh·g⁻¹ at a current density of 50 mA·g⁻¹ and admirable cycle stability (208.4 mAh·g⁻¹ at 50 mA·g⁻¹ after 500 cycles). The highly reversible structural stability and fully cross-linked properties during potassiation are revealed by ex-situ characterization. This work provides new ideas for the synthesis of new carbon materials and the development of high-performance electrodes.