Conductive NiMn-based bimetallic metal–organic gel nanosheets for supercapacitors

Abstract

Recently, the easy processability and dynamic properties of metal–organic gels (MOGs) have highlighted their application in sensing, adsorption, and catalysis. However, people rarely realize the potential application of metal organic gels (MOGs) in supercapacitors due to the insufficient conductivity of most MOGs. Here, a conductive NiMn-based bimetallic metal–organic gel with controllable morphology has been manufactured via a self-assembly process with metal ion and low molecular weight gelators. The interaction of metal ion and low molecular weight gelators easily control the growth of NiMn MOG with different nanostructures, such as pieces, lines, and rods by changing the molar ratio of Ni²⁺ and Mn²⁺. Benefiting from the nanosheets, the electrode of NiMn-3 MOG exhibits an excellent capacitance of ∼692.9 F g⁻¹ at 1 A g⁻¹, a good rate performance (516.6 F g⁻¹ at 9 A g⁻¹) and a favorable conductivity (1.12 S m⁻¹). Furthermore, an asymmetric supercapacitor (ASC) device assembled with activated carbon as the negative electrode and NiMn MOG as the positive electrode exhibits a maximum energy density of 87.5 W h kg⁻¹ at a power density of 849 W kg⁻¹, and preserves great cycling stability (84.54% capacity retention after 5000 cycles). This work provides an effective strategy to manufacture NiMn MOG-based electrodes for actual energy storage and conversion applications.