A Gas-Steamed MOF Route to P-Doped Open Carbon Cages with Enhanced Zn-Ion Energy Storage Capability and Ultrastability

Carbon micro/nanocages have received great attention, especially in electrochemical energy-storage systems. Herein, as a proof-of-concept, a solid-state gas-steamed metal-organic-framework approach is designed to fabricate carbon cages with controlled openings on walls, and N, P dopants. Taking advantage of the fabricated carbon cages with large openings on their walls for enhanced kinetics of mass transport and N, P dopants within the carbon matrix for favoring chemical adsorption of Zn ions, when used as carbon cathodes for advanced aqueous Zn-ion hybrid supercapacitors (ZHSCs), such open carbon cages (OCCs) display a wide operation voltage of 2.0 V and an enhanced capacity of 225 mAh g(-1) at 0.1 A g(-1). Also, they exhibit an ultralong cycling lifespan of up to 300 000 cycles with 96.5% capacity retention. Particularly, such OCCs as electrode materials lead to a soft-pack ZHSC device, delivering a high energy density of 97 Wh kg(-1) and a superb power density of 6.5 kW kg(-1). Further, the device can operate in a wide temperature range from -25 to + 40 degrees C, covering the temperatures for practical applications in daily life.

Automated summary

Carbon micro/nanocages fabricated using a solid-state gas-steamed metal-organic-framework approach exhibit large openings on walls for enhanced kinetics of mass transport. The carbon cathodes show high operation voltage and ultralong cycling lifespan, resulting in high energy density and superb power density.