Pseudocapacitance-boosted ultrafast Na storage in a pie-like FeS@C nanohybrid as an advanced anode material for sodium-ion full batteries

• Published in: Nanoscale Vol. 1; no. 19; pp. 9218 - 9225
• Main Authors: Hou, Bao-Hua, Wang, Ying-Ying, Guo, Jin-Zhi, Ning, Qiu-Li, Xi, Xiao-Tong, Pang, Wei-Lin, Cao, An-Min, Wang, Xinlong, Zhang, Jing-Ping, Wu, Xing-Long
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01.01.2018
• Subjects: Anodes; Carbon; Electrode materials; Electrodes; Reaction kinetics; Rechargeable batteries; Sodium-ion batteries
• ISSN: 2040-3364; 2040-3372; 2040-3372
• DOI: 10.1039/c7nr09674g

In order to develop promising anode materials for sodium-ion batteries (SIBs), a novel pie-like FeS@C (P-FeS@C) nanohybrid, in which all ultrasmall FeS nanocrystals (NCs) are completely embedded into the carbon network and sealed by a protective carbon shell, has been prepared. The unique pie-like structure can effectively speed up the kinetics of electrode reactions, while the carbon shell stabilizes the FeS NCs inside. Studies show that the electrochemical reaction processes of P-FeS@C electrodes are dominated by the pseudocapacitive behavior, leading to an ultrafast Na + -insertion/extraction reaction. Hence, the prepared P-FeS@C nanohybrid exhibits superior Na-storage properties especially high rate capability in half cells. For example, it can deliver reversible capacities of 555.1 mA h g −1 at 0.2 A g −1 over 150 cycles and about 60.4 mA h g −1 at 80 A g −1 (an ultrahigh current density even higher than that of the capacitor test). Furthermore, an advanced P-FeS@C//Na 3 V 2 (PO 4 ) 2 O 2 F full cell has been assembled out, which delivers a stable specific capacity of 441.2 mA h g −1 after 80 cycles at 0.5 A g −1 with a capacity retention of 91.8%. A novel pie-like FeS@C nanohybrid has been prepared, which exhibits pseudocapacitance-prompted ultrafast Na storage and superior Na-ion full-cell performance.