Sulfonated polyaniline coated Prussian blue analog derived Mn-Fe oxide composite electrode for all-solid-state flexible supercapacitors

Abstract

Polyaniline (PANi) is extensively utilized for supercapacitors because of its peculiar doping mechanism and excellent redox properties. However, since its one-dimensional molecular chains usually exist in an aggregated and disordered structure, the PANi backbone is subject to deformation and degradation during charging and discharging processes, which leads to its low actual specific capacitance and rapid structural collapse. To address these challenges, we propose the synthesis of a sulfonated polyaniline (SPANi) structure by one-step copolymerization, which immobilizes the sulfonic acid group (−SO₃H) onto the PANi backbone. The presence of −SO₃H helps to promote the redox reaction of PANi to proceed and augment the pseudocapacitive properties. Subsequently, SPANi is further polymerized in-situ on Mn-Fe oxide (MFO) derived from Prussian blue analog to prepare a novel conductive polymer-encapsulated bimetallic oxide hollow nanocube composite material, designated as SPANi/MFO. It demonstrates a remarkable specific capacitance of 597.06 F g⁻¹ at 1 A g⁻¹ owing to its superior structural, and maintains 89.05 % of its initial capacity after 10,000 cycles. Assembly of supercapacitors with PAAM/H₂SO₄ gel electrolyte demonstrates a notable specific capacitance of 177.43 F g⁻¹ and cycling performance of 90.32 % after 10,000 cycles, the device also exhibits an energy density of 15.77 Wh kg⁻¹ (400 W kg⁻¹). This paper provides a useful method to prepare modified PANi coated functional nanomaterial composite electrodes for supercapacitors.