Guangdi Nie,Xiaofeng Lu,Maoqiang Chi,Yun Zhu,Zezhou Yang,Na Song,Ce Wang
The incompetency of conventional single-phase electrode materials remains a stumbling block for making further breakthroughs in high-performance supercapacitors. In this work, α-Fe 2 O 3 nanotube@MnO 2 nanosheet hierarchical networks with tunable mass ratio of MnO 2 to α-Fe 2 O 3 are prepared via a simple two-step method for supercapacitor electrodes. The α-Fe 2 O 3 @MnO 2 core-shell heterostructures, especially the FM10020 containing 60.1 wt% of MnO 2 , exhibit a larger specific capacitance of 289.9 F g −1 at 1.0 A g −1 , a better rate capability of 40.8% at 5.0 A g −1 and a higher cycling stability of 85.3% after 1200 cycles than the pure MnO 2 , highlighting the advantages of such unique configuration accompanied by the synergistic effect. It is believed that these intriguing results will provide an alternative way for the construction of metal oxide-based composite nanostructures with improved electrochemical performance.
Chenglong Li,Shuang Wang,Yinghe Cui,Xiaodong Wang,Zhipeng Yong,Dan Liang,Yue Chi,Zhe Wang
Two-dimensional transition metal carbides/nitrides (MXene) have excellent physicochemical properties, but the restacking of MXene films restricts their development towards flexible supercapacitors with high energy density . Introducing Polyaniline (PANI) into the MXene layer and expanding the interlayer distance of the MXene can reduce the effect of restacking on the MXene after compounding. However, despite the excellent electronic conductivity of the composited MXene/PANI (MP), its internal slow ionic kinetics becomes a fundamental limitation of the electrochemical performance after the MP loading increases. To compensate for this weakness, MP films are often scaled down to a few micrometers in size (<2 mg cm −2 ), which limits their development. Here, we introduce α-Fe 2 O 3 /MnO 2 (FM) into MP for the first time by designing a sandwich structure, which significantly improves the bulk capacitance. Due to a large number of active sites and good hydrophilic properties on the MXene surface, FM can interact with the MP. By complexing with MP, the accumulation and loss of FM can be reduced. At the same time, the effect of increasing loading on the electrochemical performance of MP can be compensated. The MXene-PANI/α-Fe 2 O 3 -MnO 2 /MXene-PANI (MP/FM/MP) electrode still exhibits high capacitive performance (661 F g −1 , 3138 mF cm −3 ) when the MP loading reaches 5 mg cm −2 , with excellent mechanical properties and increased flexibility. In addition, the corresponding symmetric supercapacitor also shows a remarkable energy density of 53.32 Wh·L −1 (17.45 Wh kg −1 ). This study provides a way to fabricate MXene-based electrodes with high loadings by designing sandwich-structured electrodes.
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