A facile one-pot synthesis of FeO /carbon/graphene composites as superior anode materials for lithium-ion batteries

One-Step Engineering Carbon Supported Magnetite Nanoparticles Composite in a Submicron Pomegranate Configuration for Superior Lithium-Ion Storage

In this work, magnetite nanoparticles (Fe₃O₄) that are well dispersed by a submicron sized carbon framework in a pomegranate shape are engineered using a flexible one-step spray pyrolysis strategy. Under inert gas atmosphere, the homogeneously mixed Fe³⁺ ions and chitosan (CS) molecules are in situ transformed to Fe₃O₄ nanoparticles and spherical nitrogen-doped carbon coating domains, respectively. Moreover, the obtained Fe₃O₄@C composite exhibits a unique submicron sized pomegranate configuration, in which favorable electric/ionic pathways have been constructed and the Fe₃O₄ nanoparticles have been effectively dispersed. When used as an anode electrochemical active material, the Fe₃O₄@C composite exhibits impressive lithium-ion storage capabilities, and maintains a reversible capacity of 500.2 mAh·g^-1 after 500 cycles at a high current density of 1000 mA·g^-1 as well as good rate capability. The strategy in this work is straightforward and effective, and the synthesized Fe₃O₄@C material has good potential in wider applications.

Rationally engineering a hierarchical porous carbon and reduced graphene oxide supported magnetite composite with boosted lithium-ion storage performances

Ferric gallate (Fe-GA), an ancient metal-organic framework (MOF) material, has been recently employed as an eco-friendly and cost-effective precursor sample to synthesize a porous carbon confined nano-iron composite (Fe/RPC), and the Fe element in the Fe/RPC sample could be further oxidized to Fe₃O₄ nanocrystals in a 180 °C hydrothermal condition. On this foundation, this work reports an optimized approach to engineering a hierarchical one-dimensional porous carbon and two-dimensional reduced graphene oxide (RGO) supporting framework with Fe₃O₄ nanoparticles well dispersed. Under mild hydrothermal condition, the redox reaction between metal iron atoms from Fe/RPC and surface functional radicals from few-layered graphene oxide sheets (GO) is triggered. As a result, reinforced microstructure and improved atomic efficiency have been achieved for the Fe₃O₄@RPC/RGO sample. The homogeneously dispersed Fe₃O₄ nanoparticles with controlled size are anchored on the surface of the larger sized RGO coating layers while the smaller sized RPC domains are embedded between the RGO sheets as spacer. Challenges including spontaneous aggregation of RPC, over exposure of Fe₃O₄ nanoparticles and excessive restacking of RGO have been significantly inhibited. Furthermore, micro-sized carbon fiber (CF) is chosen as a structural reinforcement additive during electrode fabrication, and the Fe₃O₄@RPC/RGO sample delivers a good specific capacity of 1170.5 mAh·g^-1 under a current rate of 1000 mA·g^-1 for 500 cycles in the half cell form. The reasons for superior electrochemical behaviors have been revealed and the lithium-ion storage performances of the Fe₃O₄@RPC/RGO sample in the full cell form have been preliminarily investigated.

Sodium carboxymethylcellulose induced engineering a porous carbon and graphene immobilized magnetite composite for lithium-ion storage

Immobilizing nanosized electrochemically active materials with supportive carbonaceous framework usually brings in improved lithium-ion storage performance. In this work, magnetite nanoparticles (Fe₃O₄) are stabilized by both porous carbon domains (PC) and reduced graphene oxide sheets (RGO) to form a hierarchical composite (Fe₃O₄@PC/RGO) via a straightforward approach. The PC confined iron nanoparticle intermediate sample (Fe@PC) was first fabricated, where sodium carboxymethylcellulose (Na-CMC) was employed not only as a cross-linker to trap ferric ions for synthesizing a Fe-CMC precursor sample, but also as the carbon source for PC domains and iron source for Fe nanoparticles in a pyrolysis process. The final redox reaction between Fe@PC and few-layered graphene oxide (GO) sheets contributed to the formation of Fe₃O₄ nanoparticles with reduced size, avoiding any severe aggregation or excessive exposure. The Fe₃O₄@PC/RGO sample delivered a specific capacity of 522.2 mAh·g^-1 under a current rate of 1000 mA·g^-1 for 650 cycles. The engineered Fe@PC and Fe₃O₄@PC/RGO samples have good prospects for application in wider fields.

Synthesis of Nickel Fumarate and Its Electrochemical Properties for Li-Ion Batteries

Metal–organic frameworks (MOFs) have found a potential application in various domains such as gas storage/separation, drug delivery, catalysis, etc. Recently, they have found considerable attention for energy storage applications such as Li- and Na-ion batteries. However, the development of MOFs is plagued by their limited energy density that arises from high molecular weight and low volumetric density. The choice of ligand plays a crucial role in determining the performance of the MOFs. Here, we report a nickel-based one-dimensional metal-organic framework, NiC4H2O4, built from bidentate fumarate ligands for anode application in Li-ion batteries. The material was obtained by a simple chimie douce precipitation method using nickel acetate and fumaric acid. Moreover, a composite material of the MOF with reduced graphene oxide (rGO) was prepared to enhance the lithium storage performance as the rGO can enhance the electronic conductivity. Electrochemical lithium storage in the framework and the effect of rGO on the performance have been investigated by cyclic voltammetry, galvanostatic charge–discharge measurements, and EIS studies. The pristine nickel formate encounters serious capacity fading while the rGO composite offers good cycling stability with high reversible capacities of over 800 mAh g−1.

High-capacity and high-rate Ni-Fe batteries based on mesostructured quaternary carbon/Fe/FeO/Fe3O4 hybrid material

The Ni-Fe battery is a promising alternative to lithium ion batteries due to its long life, high reliability, and eco-friendly characteristics. However, passivation and self-discharge of the iron anode are the two main issues. Here, we demonstrate that controlling the valence state of the iron and coupling with carbon can solve these problems. We develop a mesostructured carbon/Fe/FeO/Fe₃O₄ hybrid by a one-step solid-state reaction. Experimental evidence reveals that the optimized system with three valence states of iron facilitates the redox kinetics, while the carbon layers can effectively enhance the charge transfer and suppress self-discharge. The hybrid anode exhibits high specific capacity of 604 mAh⋅g⁻¹ at 1 A⋅g⁻¹ and high cyclic stability. A Ni-Fe button battery is fabricated using the hybrid anode exhibits specific device energy of 127 Wh⋅kg⁻¹ at a power density of 0.58 kW⋅kg⁻¹ and maintains good capacity retention (90%) and coulombic efficiency (98.5%).

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A quaternary hybrid has been fabricated by a one-step solid-state reaction.

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Controlling the valence state of iron facilitates redox kinetics and charge transfer.

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The hybrid anode exhibits high specific capacity of 604 mAh⋅g⁻¹ at 1 A⋅g⁻¹.

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The NiFe battery exhibits specific energy of 127 Wh⋅kg⁻¹ and superior durability.