Edge enriched cobalt ferrite nanorods for symmetric/asymmetric supercapacitive charge storage. (1st September 2018)

• Record Type: Journal Article
• Authors: Lalwani, Shubra; Marichi, Ram Bhagat; Mishra, Monu; Gupta, Govind; Singh, Gurmeet; Sharma, Raj Kishore
• Is Part Of: Electrochimica acta. Volume 283(2018)
• Page Start: 708
• Page End: 717
• Publication Date: 2018-09-01
• Subjects: Cobalt ferrite -- Porous nanorods -- Active sites -- Edges -- Asymmetric supercapacitor; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.07.008
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: For maximum and efficient charge storage and delivery, porous nanorods with active sites can offer a unique set of advantages. Herein, hierarchically porous (0.2–200 nm) cobalt ferrite (CoFe2 O4 ) nanorods are hydrothermally prepared by tuning oleic acid concentration (100–500 μL) with subsequent annealing (400 °C). These hierarchical pores (with edges and cavities) raise the specific surface area of CoFe2 O4 nanorods to 154 m 2 g −1 . In addition, 80% of CoFe2 O4 sites become accessible boosting the capacitance to a high value (460.5 F g −1 at 1.0 A g −1 ), while retaining excellent cyclic stability (95.8% for 5000 cycles). Maximum pseudocapacitive contribution from these electrochemically active sites is ensured by rapid diffusion of electrolytic OH − ions (5.8 × 10 −8 cm 2 s −1 ). Moreover, on assembling these nanorods as a positive electrode in asymmetric configuration (graphene nanoribbons as negative electrode), the cell exhibits an outstanding energy density (33.5 Wh kg −1 at 727.8 W kg −1 ), almost double of its symmetric (16.5 Wh kg −1 at 288 W kg −1 ) counterpart. Graphical abstract: Edge enriched Cobalt ferrite nanorods as positive electrode for flexible asymmetric supercapacitor. Image 1