Fe₃O₄/Nitrogen‐Doped Carbon Electrodes from Tailored Thermal Expansion toward Flexible Solid‐State Asymmetric Supercapacitors

Abstract

template-assisted carbonizations, [5,6] electrochemistry deposition, [7] spontaneous gas-foaming, [8] "gel-blowing," [9] "Pharaoh's snakes" reaction, [10] and nanocasting have been developed, and allowing different types of NCMs synthesis from various organic precursors. [11] Although it is possible to obtain desired NCMs with tailored structures and properties by carefully selecting specific procedures, [12] these processes always suffer from removing a template and multi-step operation. [13] Thus, novel strategies to one-pot synthesizing multilevel heteroatom-doped NCMs are still being urgently desired. [14] Advanced NCMs would be potentially promising for supercapacitors (SCs) applications because of the unique structural advantages, [15] such as a large specific surface area and high electrical conductivity. [16] Especially, with the increasing interests in mobile electronics, portable electronic devices, electronic textiles, and skins, highly flexible, and safe energy storage devices with high energy and power densities maintain a growing demand. [17] NCMbased SCs can bridge the gap between conventional capacitors and cells, have been widely used in various areas due to their rapid energy transfer, long cycle life, sustained stability, and a wide range of working temperatures. [18] Moreover, after combination of transition metal compounds (TMCs) including metal oxides (e.g., MnO 2 , Fe 2 O 3 , CuO), [19] metal sulfides (MoS 2 ), [20] metal nitrides (e.g., TiN, Fe 2 N), [21] metal-organic frameworks, [22] and metal hydroxide (e.g., Ni(OH) 2 ), [23] the key faradic capacitance of NCM electrodes can be prominently enhanced. Among the TMCs, ferroferric oxide (Fe 3 O 4 ) is particularly promising since: [24] 1) a higher conductivity than other TMCs (σ = 2 × 10 4 S m −1 ); 2) a relatively low potential and a high theoretical capacity (≈346.5 mAh g −1 ) on the basis of the possible variation of iron's valence states (Fe 3+ ↔ Fe 0 ) in alkaline aqueous solution, which can deliver large voltage windows (≤−1.3 V vs Ag/AgCl) and high pseudocapacitance attributions; 3) ecofriendliness during the synthesis process, natural abundance, and compatibility. For instance, Fe 3 O 4 -carbon nanosheets, [25] graphene-wrapped Fe 3 O 4 , [26] rGO-encapsulated Fe 3 O 4 nanocube, [27] graphene aerogel-supported Fe 3 O 4 , [28,29] carbon nanotube/cubic Fe 3 O 4 , [30] and Fe 3 O 4 /activated carbon [31] have been designed to achieve high electrochemical performance. [32] Although the Transition metal oxide and heteroatoms doped carbon are promising in high performance energy storage upon complete redox reaction. Herein, nanoparticle-embedded carbon nanosheets are fabricated by a one-pot tailored thermally expansion of viscous precursors. The obtained biomass carbon exhibits ideal surface area, crystal structures, and heteroatom doping. Benefiting from the synergistic effect of the constituent components, this composite electrode reaches a high potential window of 1.1 V and delivers a good specific capacitance of 522.7 F g −1 in aqueou...

A sequential process to synthesize Fe3O4@MnO2 hollow nanospheres for high performance supercapacitors

“…8(b)). [47][48][49][50][51] At the same time, two Fe 3 O 4 @MnO 2 -HNS||AC devices in series can power an LED for more than 2 min (Fig. 8(c) and the video of the ESI †).…”

Improvement of Supercapacitor Performance through Enhanced Interfacial Interactions Induced by Sonication

“… − The gravimetric capacitance of the synthesized Fe 3 O 4 /rGO nanocomposite was also estimated and was found to be superior to those of other iron oxide carbon-based materials (refer to Table S5 in the Supporting Information). ,− …”

N-Doped Porous Carbon-Nanofiber-Supported Fe3C/Fe2O3 Nanoparticles as Anode for High-Performance Supercapacitors

“…The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/molecules28155751/s1, Figure S1 S1: SSA, pore volume, and average pore diameter of NCFC, NCFCO, and NCFO; Table S2: Specific capacitances of NCFCO and previously reported Fe-based oxides/carbides; Table S3: Preparation conditions of NCFC, NCFCO, and NCFO. References [14,18,44,[53][54][55][56][57][58][59] are cited in the Supplementary Materials.…”