CoFe₂O₄ Hollow Spheres-Decorated Three-Dimensional rGO Sponge for Highly Efficient Electrochemical Charge Storage Devices

Abstract

The energy demand, the crisis of fossil fuels, and the increasing popularity of portable and wearable electronics in the global market have triggered the demand to develop high-performance flexible all-solid-state supercapacitors that are capable of delivering high energy at high power density as well as being safely entrenched in those electronics. Herein, we have designed a nanocomposite, 80CF hs -20rGO sp , which exhibits a high specific capacitance ( C S ) value of 1032 F g –1 at 3 A g –1 . Utilizing this nanocomposite as the cathode and reduced graphene oxide sponge (rGO sp ) as the anode, a flexible all-solid-state asymmetric device has been fabricated. In this device, poly(vinyl alcohol) (PVA) gel embedded with a mixture of 3 M KOH and 0.1 M K 4 [Fe(CN) 6 ] was used as an electrolyte cum separator. The fabricated device showed the capability to deliver an energy density of 65.8 W h kg –1 at a power density of 1500 W kg –1 and retained its capability even after various physical deformations. The device also exhibited a long cycle life and retained ∼96% of its C S value after 5000 cycles. Moreover, the fabricated flexible all-solid-state device successfully illuminated light-emitting diodes, which proved its potential use in real-life supercapacitor applications. The obtained results revealed the excellent electrochemical performances of the fabricated device and rendered it a promising candidate in the energy sector.

A high-performance flexible energy storage device from biomass-derived porous carbon supported MnCo2O4 nanorods and MnO2 nanoscales

“…4d). 4,35 The formation of MCO, MCO-MnO 2 , PC, and MCO-MnO 2 -PC was conrmed by XRD, FT-IR, Raman, FESEM, HRTEM, SAED, EDX, and XPS analyses. The synthetic protocol and the formation of the nanocomposite are illustrated in Scheme 1.…”

“…2 In order to attain the enormous global energy demand that is rising annually by $3-4%, the development of energy storage systems that can store the energy produced by these erratic natural resources is very imperative. 3,4 In this scenario, electrochemical energy storage (EES) devices are emerging as the global leaders in the energy sector. 5,6 Supercapacitors (SCs) are the leading-edge EES devices which are expected to be dominantly used in multiple and major global sectors such as public transportation, communication devices, biomedical implants, space, military, etc.…”

“…At present, the application of SCs in the emergency door of an Airbus A380 and in a public transport vehicle in China, Capabus (since 2006) provides two successful examples of commercial usage of SCs. 3,4 Flexible energy storage devices have revolutionized the global market of electronics due to their light weight, litheness, easy portability, and capability to perform even under remarkable physical deformations. 7 The rising popularity of portable and wearable electronics and escalating demand for biomedical implants have driven the quest to develop exible devices which can not only deliver high energy and power densities at various physical deformations but also possess long durability as well as being non-harmful for human health.…”

“…7,13 So, researchers around the world are paying more attention to developing high-performance exible ASCs that can accomplish the prospects of modern electronic technologies. 4 Flexible SCs usually consist of exible electrodes having excellent electrochemical properties, a separator and a compatible electrolyte system in a exible assembly. 14 Mixed transition metal oxides like MnCo 2 O 4 (MCO) have been gaining a lot of attention as electrode materials owing to their very high theoretical specic capacitance (C S ) value ($3620 F g À1 ), high structural stability, excellent electrochemical as well as physicochemical properties, and multiple valences.…”

CoFe2O4 Nanoparticles Grown within Porous Al2O3 and Immobilized on Graphene Nanosheets: A Hierarchical Nanocomposite for Broadband Microwave Absorption

“… 26 Pure CF showed XRD peaks at 2θ = 18.4, 30.3, 35.6, 37.4, 43.3, 53.7, 57.2, and 62.7°, which arises due to the presence of the (111), (220), (311), (222), (400), (422), (511), and (440) crystallographic planes of CF with a cubic crystal system [JCPDS Card no: 22-1086] ( Figure S1b ). 27 In the case of pure graphene (Gr), the diffraction peaks appeared at 2θ = 25.4 and 43.3°, which correspond to the (002) and (100) planes of graphene [JCPDS Card no: 01-0646] ( Figure S1d ). The XRD patterns of PA–CF nanocomposites display all of the characteristic peaks of both PA and CF and as a representative, the XRD pattern of 60PA-40CF is displayed in Figure S1c .…”