Wenyu Bai,Guangpeng Ma,Xinpu Zhou,Tongtong Gao,Yu Luo,Di Yu,Shuang Wang
Traditional two-dimensional transition metal carbides/nitrides (MXene) have gained much academic concern due to their excellent physicochemical properties, but their susceptibility to self-stacking leads to poor cyclic stability. In this paper, an MXene-based electrode active material was successfully prepared. The generated modified PPy (g-PPy) increases the active site, increases the accessibility of ions, and can give full play to the pseudocapacitance. By the combination of modified PPy (g-PPy) nanoparticles with pseudocapacitive behavior polymerized in situ on sulfonated cellulose (SC) and MXene , not only the electrochemical performance was improved by exploiting the synergy between different electrode materials and different energy storage mechanisms, but also the MXene as a skeleton limited the volume expansion and contraction of PPy during charge/discharge cycles and the g-PPy and SC composites (g-PPy@SC) as a spacer supported the MXene layer, resulting in much higher cycle stability. Cycle stability of 98.4 % even after 10,000 cycle tests. In addition, a symmetric supercapacitor assembled from this electrode material maintains a stability of 84.4 % under 10,000 cycles at a low temperature of −40 °C. Therefore, this study provides a feasible method for the preparation of MXene-based electrodes with high cycling stability.
Wenyu Bai,Chenglong Li,Feng Pan,Yu Luo,Tongtong Gao,Di Yu,Xiaorui Wang,Han Sun,Shuang Wang
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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