Energizing Fe2O3-based supercapacitors with tunable surface pseudocapacitance via physical spatial-confining strategy

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-02, Vol.406, p.126875, Article 126875
• Main Authors: Cheng, Situo, Zhang, Yaxiong, Liu, Yupeng, Sun, Zhenheng, Cui, Peng, Zhang, Junli, Hua, Xiaohui, Su, Qing, Fu, Jiecai, Xie, Erqing
• Format: Article
• Language: English
• Subjects: Asymmetric supercapacitor; Fe2O3-based anode; Long-term cycling stability; Spatial-confining strategy; Surface pseudocapacitance
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.126875

[Display omitted] •A physical spatial-confining strategy enhances the performance of Fe2O3 electrode.•Physical separation induced by decorating Al2O3 benefits for the rate performance.•The resultant Fe2O3-based anode shows an excellent capacitance of 2371F g−1.•The capacitance of resultant Fe2O3-based anode retains 95.38% after 5000 cycles.•The novel-designed ASC device delivers an energy density as high as 174 W h kg−1. Developing an anode with outstanding electrochemical properties remains a significant challenge in building high-performance asymmetric supercapacitor devices. The promising Fe2O3-based anode shows exceptional theoretical electrochemical performance but limited by its undesired practical energy density and long-term cycling stability. Herein, we propose a physical spatial-confining strategy to enhance the electrochemical performance of the Fe2O3-based electrode with tunable surface pseudocapacitance using redox electrolyte Na2SO3. By introducing Al2O3 nanograins on the surface of Fe2O3, electrolyte Na+ can diffuse through the surface-anchored Al2O3 nanograin but SO32- was physically blocked due to the Na+ ions fast diffusion nature of Al2O3 during the electrochemical operations. And a positive charge center by Na+ was formed on the side of Fe2O3, which attracts SO32- securing a stable bridge between the dissociative SO32- groups and electrode. Such a physically constrained structure ensures the fast dual-ion-involved redox reactions, leading to a significant electrochemical performance (including capacitance performance and long-term cycling stability). The Al2O3/Fe2O3-based anode delivers a high capacitance of 2371F g−1 at 5 mV s−1 with a capacitance retention of 1277F g−1 even at 200 mV s−1, which also shows superior cycling stability of 95.38% after 5000 cycles. A novel dual-electrolyte Al2O3/Fe2O3@CNTs/Na2SO3//MnO2@CNTs/Na2SO4 asymmetric supercapacitor device with a potential window of 0–2.2 V was configured, which shows the remarkable performance of energy density of 174 W h kg−1 at a power density of 4492 W kg−1.