Manganese Hexacyanoferrate/Polyaniline Composite Electrode with High Cycling Stability for Antifreezing Supercapacitors

Prussian blue analogs (PBAs) have garnered significant attention in the field of electrochemistry due to their open three-dimensional backbone structure and superior redox reversibility. However, the electrochemical performance of PBAs still needs to be improved, such as their low conductivity, poor cycle life, and suboptimal energy/power density. In this study, manganese hexacyanoferrate (MnHCF), which exhibits enhanced capacitance and ion-transport capabilities, was synthesized via a coprecipitation method. Subsequently, polyaniline (PANI) was uniformly deposited onto MnHCF through a polymerization process, resulting in a composite material, MnHCF/PANI, characterized by an effective cladding structure. The external PANI layer not only augments the electrode’s capacitance but also forms a surface redox reaction buffer, thereby improving cycling stability. The synergistic interaction between the MnHCF framework and the PANI layer endowed the MnHCF/PANI electrode with a high specific capacitance of (403.5 F g –1 )and excellent long-term cycling stability, retaining 87.5% of its initial capacitance after 10 000 cycles. Additionally, the device was assembled into a SCs using a polyacrylamide/glycerol (PAAM/Gly) antifreezing gel as the electrolyte. This configuration yielded a high specific capacitance of 146 F g –1, maintaining 90.74% of its capacitance after 10 000 charge/discharge cycles. Notably, at low temperatures, the device achieved a specific capacitance of 112.6 F g –1 with 77.12% capacitance retention. This research provides a simple and effective approach for the development of MnHCF-based SCs that exhibit resistance to low-temperature conditions.