High-performance anode and cathode materials from single-source metal-organic frameworks for long-life hybrid supercapacitors

The advancement of metal-organic framework (MOF)-based electrodes for supercapacitors is often limited by low intrinsic electronic and ionic conductivities and structural instability. Herein, we present a single-source strategy using a versatile Co-ZIF precursor for the synthesis of two novel high-performance hybrid electrode materials: Co-containing N-doped carbon (Co-ZC) for the anode and Co₃O₄ (ZO) for the cathode. Through thermal treatments in nitrogen and air atmospheres, the graphite rock-like Co-ZC anode features metallic cobalt particles embedded in a highly conductive carbon matrix, enhancing both electronic and ionic conductivity to promote rapid redox kinetics. Conversely, the blackstone flower-like ZO cathode is pseudocapacitive which facilitates faradaic redox reactions and achieves a notable capacity. In a three-electrode configuration, the Co-ZC anode exhibits a superior capacitance of 699.4 F g⁻¹ at 2 mA cm⁻², outperforming Co-ZIF (126.1 F g⁻¹) and ZO (158.9 F g⁻¹) electrodes. Furthermore, a PVA-KOH gel-based solid-state ZO//Co-ZC hybrid supercapacitor was assembled. This device exhibits an impressive energy density of 15 Wh kg⁻¹ and a significant power density of 6000 W kg⁻¹, with an exceptional capacitance retention of 86.6 % after increased current density and enhanced capacitance reaching 110.4 % after 23,000 charge-discharge cycles. This scalable MOF-derived strategy offers a promising pathway for high-performance energy storage solution.