A Nanocrystalline Fe2O3 Film Anode Prepared by Pulsed Laser Deposition for Lithium-Ion Batteries

Core-Double-Shell TiO2@Fe3O4@C Microspheres with Enhanced Cycling Performance as Anode Materials for Lithium-Ion Batteries

Due to the volume expansion effect during charge and discharge processes, the application of transition metal oxide anode materials in lithium-ion batteries is limited. Composite materials and carbon coating are often considered feasible improvement methods. In this study, three types of TiO2@Fe3O4@C microspheres with a core-double-shell structure, namely TFCS (TiO2@Fe3O4@C with 0.0119 g PVP), TFCM (TiO2@Fe3O4@C with 0.0238 g PVP), and TFCL (TiO2@Fe3O4@C with 0.0476 g PVP), were prepared using PVP (polyvinylpyrrolidone) as the carbon source through homogeneous precipitation and high-temperature carbonization methods. After 500 cycles at a current density of 2 C, the specific capacities of these three microspheres are all higher than that of TiO2@Fe2O3 with significantly improved cycling stability. Among them, TFCM exhibits the highest specific capacity of 328.3 mAh·g-1, which was attributed to the amorphous carbon layer effectively mitigating the capacity decay caused by the volume expansion of iron oxide during charge and discharge processes. Additionally, the carbon coating layer enhances the electrical conductivity of the TiO2@Fe3O4@C materials, thereby improving their rate performance. Within the range of 100 to 1600 mA·g-1, the capacity retention rates for TiO2@Fe2O3, TFCS, TFCM, and TFCL are 27.2%, 35.2%, 35.9%, and 36.9%, respectively. This study provides insights into the development of new lithium-ion battery anode materials based on Ti and Fe oxides with the abundance and environmental friendliness of iron, titanium, and carbon resources in TiO2@Fe3O4@C microsphere anode materials, making this strategy potentially applicable.

Facile synthesis of nanosized Mn3O4 powder anodes for high capacity Lithium-Ion battery via flame spray pyrolysis

Mn₃O₄ powders with nanometer size are successfully synthesized by a simple one-step method via flame spray pyrolysis. The precursor droplet is generated by heating under high temperature flame with fixed flow rate, and the exothermic reaction is induced to form nanosized Mn₃O₄ powders. When used as anode material for lithium-ion battery, the Mn₃O₄ exhibits good cycling capacity and rate performance. It delivers a specific capacity of 1,182 mA h g⁻¹ over 110 cycles at a current density of 200 mA g⁻¹, and has a high capacity of 140 mA h g⁻¹ at 5,000 mA g⁻¹.

All-Solid-State Thin Film μ-Batteries for Microelectronics

Continuous advances in microelectronics and micro/nanoelectromechanical systems enable the use of microsized energy storage devices, namely solid-state thin-film μ-batteries. Different from the current button batteries, the μ-battery can directly be integrated on microchips forming a very compact "system on chip" since no liquid electrolyte is used in the μ-battery. The all-solid-state battery (ASSB) that uses solid-state electrolyte has become a research trend because of its high safety and increased capacity. The solid-state thin-film μ-battery belongs to the family of ASSB but in a small format. However, a lot of scientific and technical issues and challenges are to be resolved before its real application, including the ionic conductivity of the solid-state electrolyte, the electrical conductivity of the electrode, integration technologies, electrochemical-induced strain, etc. To achieve this goal, understanding the processing of thin films and fundamentals of ion transfer in the solid-state electrolytes and hence in the μ-batteries becomes utmost important. This review therefore focuses on solid-state ionics and provides inside of ion transportation in the solid state and effects of chemistry on electrochemical behaviors and proposes key technology for processing of the μ-battery.

Progress in Iron Oxides Based Nanostructures for Applications in Energy Storage

The demand for green and efficient energy storage devices in daily life is constantly rising, which is caused by the global environment and energy problems. Lithium-ion batteries (LIBs), an important kind of energy storage devices, are attracting much attention. Graphite is used as LIBs anode, however, its theoretical capacity is low, so it is necessary to develop LIBs anode with higher capacity. Application strategies and research progresses of novel iron oxides and their composites as LIBs anode in recent years are summarized in this review. Herein we enumerate several typical synthesis methods to obtain a variety of iron oxides based nanostructures, such as gas phase deposition, co-precipitation, electrochemical method, etc. For characterization of the iron oxides based nanostructures, especially the in-situ X-ray diffraction and ⁵⁷Fe Mössbauer spectroscopy are elaborated. Furthermore, the electrochemical applications of iron oxides based nanostructures and their composites are discussed and summarized.

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Interfacial Design on Graphene-Hematite Heterostructures for Enhancing Adsorption and Diffusion towards Superior Lithium Storage

Hematite (α-Fe₂O₃) is a promising electrode material for cost-effective lithium-ion batteries (LIBs), and the coupling with graphene to form Gr/α-Fe₂O₃ heterostructures can make full use of the merits of each individual component, thus promoting the lithium storage properties. However, the influences of the termination of α-Fe₂O₃ on the interfacial structure and electrochemical performance have rarely studied. In this work, three typical Gr/α-Fe₂O₃ interfacial systems, namely, single Fe-terminated (Fe-O₃-Fe-R), double Fe-terminated (Fe-Fe-O₃-R), and O-terminated (O₃-Fe-Fe-R) structures, were fully investigated through first-principle calculation. The results demonstrated that the Gr/Fe-O₃-Fe-R system possessed good structural stability, high adsorption ability, low volume expansion, as well as a minor diffusion barrier along the interface. Meanwhile, investigations on active heteroatoms (e.g., B, N, O, S, and P) used to modify Gr were further conducted to critically analyze interfacial structure and Li storage behavior. It was demonstrated that structural stability and interfacial capability were promoted. Furthermore, N-doped Gr/Fe-O₃-Fe-R changed the diffusion pathway and made it easy to achieve free diffusion for the Li atom and to shorten the diffusion pathway.

Pulsed Laser Deposited Films for Microbatteries

This review article presents a survey of the literature on pulsed laser deposited thin film materials used in devices for energy storage and conversion, i.e., lithium microbatteries, supercapacitors, and electrochromic displays. Three classes of materials are considered: Positive electrode materials (cathodes), solid electrolytes, and negative electrode materials (anodes). The growth conditions and electrochemical properties are presented for each material and state-of-the-art of lithium microbatteries are also reported.