Flexible Free-Standing Fe₂O₃ Nanoparticle/Carbon Shells/Graphene Films for Advanced Lithium-Ion Batteries

Abstract

High-capacity anode materials of transition-metal oxides (TMOs) usually undergo low conductivities and drastic volume variation derived from a multielectron-transfer conversion reaction mechanism, which seriously hinder the cycling stability and rate performance toward their commercialization. Herein, a free-standing Fe2O3/C shells/reduced graphene oxide (Fe2O3/C/RGO) film as an additive-free anode is fabricated by a facile two-step strategy accompanied by the physical cross-linking feature of chitosan. In this free-standing structure, the Fe2O3 nanoparticles (NPs) with diameters of 20–30 nm are encapsulated by chitosan pyrolytic C shells and further confined within a highly ordered RGO film. As a consequence, the ultrasmall Fe2O3 NPs can effectively reduce the Li+ diffusion pathway, while the C shell and RGO sheets act as a matrix to alleviate the huge volumetric change of Fe2O3 NPs during the charge/discharge process. Benefiting from the advantages of a free-standing film, the well-designed Fe2O3/C/RGO film effectively resolves long-standing challenges and achieves an admirable capacity of 609 mAh·g–1 at 1 A·g–1, a good rate performance (up to 4 A·g–1), and an outstanding cycling performance over 1000 cycles. These results provide a universal strategy to integrate TMOs with RGO to construct a flexible self-supported film for superior lithium-ion batteries.

Ultrafine FeF3·0.33H2O Nanocrystal-Doped Graphene Aerogel Cathode Materials for Advanced Lithium-Ion Batteries

“…The Fe 3+ ions were then well adsorbed on the surface of GO sheets with abundant oxygenic functional groups via the electrostatic adsorption effect, which on the surface of GO sheets (Figure 2a). 25 Subsequently, a 3D RGO aerogel scaffold was prepared by a sample freeze drying 26 As shown in Figure 2f, the corresponding SAED pattern reveals the crystal symmetry, which is well-consistent with the XRD results. 27 28 No other phases or impurities are detected, indicating a high purity of FeF 3 •0.33H 2 O under such synthetic conditions.…”

“…XRD patterns of the Fe 2 O 3 /RGO-2 precursor, unsupported FeF 3 ·0.33H 2 O, and FeF 3 ·0.33H 2 O/RGO nanocomposites are shown in Figures a and S3, where the Fe 2 O 3 /RGO-2 precursor was identified as γ-Fe 2 O 3 (JCPDS #39-1346) . After the evolution process, FeF 3 ·0.33H 2 O/RGO-1.5, FeF 3 ·0.33H 2 O/RGO-2, FeF 3 ·0.33H 2 O/RGO-5, and unsupported FeF 3 ·0.33H 2 O show the same well-defined characteristic peaks at 13.8, 23.4, 27.5, 27.8, and 34.0° assigned to the (110), (002), (022), (220), and (132) lattice planes of hexagonal tungsten bronze-type FeF 3 ·0.33H 2 O (JCPDS #76-1262), respectively .…”

“…Briefly, iron­(II) acetate was first added into the GO dispersion under intense magnetic stirring, during which Fe 2+ ions will be fast oxidized to Fe 3+ by oxygen forming a Fe­(OH) 3 colloid as the result. The Fe 3+ ions were then well adsorbed on the surface of GO sheets with abundant oxygenic functional groups via the electrostatic adsorption effect, which can effectively suppress the particle growth and agglomeration, ensuring the in situ generation of ultrafine Fe 2 O 3 nanocrystals on the surface of GO sheets (Figure a) . Subsequently, a 3D RGO aerogel scaffold was prepared by a sample freeze drying strategy.…”

A Review of Transition Metal Compounds as Functional Separators for Lithium‐Sulfur Batteries

“…Transition metal disulfides such as WS 2 [97,98] , SnS 2 [99] , TiS 2 [100,101] , VS 2 [102] have similar layered structures to MoS 2 . The metal atomic layer is sandwiched by the S atomic layer; The large specific surface area and sulfophilic properties adsorb more polysulfides; The intercalation/deintercalation mechanism is conducive to the conduction of electrons.…”

Ultra-Fine Maghemite (γ-Fe2O3) Nanoparticles Anchored on 3D Reduced Graphene Oxide Aerogels for Advanced Lithium-Ion Battery Anodes

“…For instance, our group recently proposed a facile freeze-drying selfassemble strategy to prepare a free-standing Fe 2 O 3 /rGO film, which exhibited a superior electrochemical performance for anode. 28 Also, Zhang et al reported ultrafine Fe 2 O 3 nanorods anchored on GO by a one-pot route in the presence of KMnO 4 and Ni foam, and showed an outstanding cycling stability (a reversible capacity of 1004 mAh g −1 after 500 cycles at 0.2 A g −1 ). 29 Consequently, the combination of nano-crystallization and composed with flexible graphene is expected to improve the lithium storage performance through "synergistic effect," which is of great significance to probe the structure-performance relationship for the development of highperformance TMOs-based anode materials for LIBs.…”