Co-MOF-derived stalk-flower like NiCo-LDH homostructure towards boosting electrochemical energy storage

Abstract

The rational design of the heterostructure of multi-component materials acts on electrochemical properties. However, the effect of structure and component alone on the performance is ignored. Homostructure can reflect the advantages of structural design more directly and fully tap the potential of the material itself. Herein, the homogeneous stereostructure with NiCo-LDH nanostalks (NiCo-LDH_S) and NiCo-LDH nanoflowers (NiCo-LDH_F) was synthesized through simultaneous Co-MOF in-situ etch and electrodeposition. NiCo-LDH_S not only preserves the shape of MOF rods, but also forms a firm adhesion to nickel foam. The coated NiCo-LDH_F on NiCo-LDH_S increases the loading of pseudocapacity material. As a result of the high capacity of Ni(OH)₂, the high conductivity of Co(OH)₂, as well as the stalk-flower stereostructure, the NiCo-LDH_S-F electrode demonstrates a specific capacity of 2058 F ​g⁻¹ (13994 ​mF ​cm⁻²) at 1 ​A ​g⁻¹, along with an ultrahigh rate capability, retaining 73.9 ​% of its capacity at 20 ​A ​g⁻¹. Moreover, the assembled NiCo-LDH_S-F//AC hybrid supercapacitor (HSC) exhibits striking energy and power densities of 48.44 ​Wh·kg⁻¹ (0.78 ​mWh·cm⁻²) and 800 ​W ​kg⁻¹ (12.8 ​mW ​cm⁻²), respectively. Notably, after 10,000 consecutive charging and discharging cycles, the device maintains a capacity retention of 85.36 ​%, demonstrating its good cycling stability. These findings prove the essentiality of designing homogeneous structure for the advancement of energy storage performance.