High stability supercapacitors based on MXene/Spherical g-PPy composite electrodes
The choice of electrode materials affects the electrochemical performance of supercapacitors, and the selection of suitable electrode materials is necessary to enable the industrialization of supercapacitors. The conductive polymer polypyrrole is well known to researchers for its excellent electrochemical properties, but pure polypyrrole does not fulfill its advantages. The disadvantage is that the microstructure of the polypyrrole molecules, which is favorable for energy storage when supercapacitors are being charged and discharged, is greatly damaged by the contraction/expansion of the polypyrrole molecular chains, which directly affects the electrochemical performance of the supercapacitors assembled subsequently. So firstly, we modified PPy by using the functional group nature of 3-amino-4-methylene-phenylboronic acid (g-PPy) to give it more active sites. Secondly, MXene acts as the backbone of g-PPy, which limits the expansion and contraction of the volume supercapacitors and improves cycle stability when charging and discharging. In contrast, the compounded MXene/g-PPy has good specific capacitance and stability after several thousand cycles, due to the nature of the functional group of 3-amino-4-methylenebenzeneboronic acid, a large number of g-PPy active sites, the good hydrophilicity of the MXene surface for interaction with sodium dodecylbenzene sulfonate and the hydrogen bonding between MXene and g-PPy, Even after 10000 charge/discharge cycles, its stability is significantly improved with a capacity retention rate of 98.6 %. In addition, the corresponding symmetrical supercapacitors were tested to exhibit significant cycling stability at a low temperature. This study, therefore, provides a method for the preparation of MXene based electrodes with high cycling stability by modifying the electrodes.
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