Advances in the synthesis and processing of graphene-based materials have presented the opportunity to design novel lithium-ion battery (LIB) anode materials that can meet the power requirements of next-generation power devices. In this work, a poly(methacrylic acid) (PMAA)-induced self-assembly process was used to design super-mesoporous Fe 3 O 4 and reduced-graphene-oxide (Fe 3 O 4 @RGO) anode materials. We demonstrate the relationship between the media pH and Fe 3 O 4 @RGO nanostructure, in terms of dispersion state of PMAA-stabilized Fe 3 O 4 @GO sheets at different surrounding pH values, and porosity of the resulted Fe 3 O 4 @RGO anode. The anode shows a high surface area of 338.8 m 2 g −1 with a large amount of 10–40 nm mesopores, which facilitates the kinetics of Li-ions and electrons, and improves electrode durability. As a result, Fe 3 O 4 @RGO delivers high specific-charge capacities of 740 mA h g −1 to 200 mA h g −1 at various current densities of 0.5 A g −1 to 10 A g −1 , and an excellent capacity-retention capability even after long-term charge–discharge cycles. The PMAA-induced assembly method addresses the issue of poor dispersion of Fe 3 O 4 -coated graphene materials—which is a major impediment in the synthesis process—and provides a facile synthetic pathway for depositing Fe 3 O 4 and other metal oxide nanoparticles on highly porous RGO.
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Structurally and chemically engineered graphene for capacitive deionization
Highly efficient capacitive deionization (CDI) relies on unimpeded transport of salt ions to the electrode surface. Graphene is an ideal candidate to provide superb conditions for ion adsorption as it possesses high theoretical surface area and electrical conductivity. When ions are stored solely within the electric double layers (EDLs), a hydrophilic graphene surface with hierarchical pores can maximize the accessible surface area and promote the ion transport. In the case of synergistic ion storage via electrostatic adsorption and faradaic redox reaction, graphene can act as both the electron highway and the reciprocal spacer to provide surface-confined effects. Substantially, structural and chemical engineering towards graphene can enhance the ion removal capacity and rate, and improve the charge efficiency and ion selectivity. In this review, we keep pace with the in-depth studies of CDI technologies and recent progress on graphene-based materials for CDI. Major challenges in the rational assembly of the desired material functionalities in terms of surface area, pore structure, and hydrophilicity are addressed. As electrode materials develop, the ultimate goal is to achieve highly efficient, energy-saving, and environment-friendly CDI.
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- Award ID(s):
- 1661699
- NSF-PAR ID:
- 10294042
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 9
- Issue:
- 3
- ISSN:
- 2050-7488
- Page Range / eLocation ID:
- 1429 to 1455
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d0ta10087k
