Refine
Document Type
Language
- English (7)
Is part of the Bibliography
- yes (7)
Keywords
- anode materials (1)
- battery (1)
- binder-free electrodes (1)
- carbon encapsulation (1)
- electrode (1)
- electrode design (1)
- electrolyte (1)
- electrospinning (1)
- energy storage (1)
- flexible electrodes (1)
Scientific Unit
- Energy Materials (7)
This study presents a novel approach to developing high-performance lithium-ion battery electrodes by loading titania-carbon hybrid spherogels with sulfur. The resulting hybrid materials combine high charge storage capacity, electrical conductivity, and core-shell morphology, enabling the development of next-generation battery electrodes. We obtained homogeneous carbon spheres caging crystalline titania particles and sulfur using a template-assisted sol-gel route and carefully treated the titania-loaded carbon spherogels with hydrogen sulfide. The carbon shells maintain their microporous hollow sphere morphology, allowing for efficient sulfur deposition while protecting the titania crystals. By adjusting the sulfur impregnation of the carbon sphere and varying the titania loading, we achieved excellent lithium storage properties by successfully cycling encapsulated sulfur in the sphere while benefiting from the lithiation of titania particles. Without adding a conductive component, the optimized material provided after 150 cycles at a specific current of 250 mA g–1 a specific capacity of 825 mAh g–1 with a Coulombic efficiency of 98%.
Batteries employing transition-metal sulfides enable high-charge storage capacities, but polysulfide shuttling and volume expansion cause structural disintegration and early capacity fading. The design of heterostructures combining metal sulfides and carbon with an optimized morphology can effectively address these issues. Our work introduces dopamine-coated copper Prussian blue (CuPB) analogue as a template to prepare nanostructured mixed copper–iron sulfide electrodes. The material was prepared by coprecipitation of CuPB with in situ dopamine polymerization, followed by thermal sulfidation. Dopamine controls the particle size and favors K-rich CuPB due to its polymerization mechanism. While the presence of the coating prevents particle agglomeration during thermal sulfidation, its thickness demonstrates a key effect on the electrochemical performance of the derived sulfides. After a two-step activation process during cycling, the C-coated KCuFeS2 electrodes showed capacities up to 800 mAh/g at 10 mA/g with nearly 100% capacity recovery after rate handling and a capacity of 380 mAh/g at 250 mA/g after 500 cycles.
Binder is a crucial component in present-day battery electrodes but commonly contains fluorine and requires coating processing using organic (often toxic) solvents. Preparing binder-free electrodes is an attractive strategy to make battery electrode production and its end-of-use waste greener and safer. Herein, electrospinning is employed to prepare binder-free and self-standing electrodes. Such electrodes often suffer from low flexibility, and the correlation between performance and flexibility is usually overlooked. Processing parameters affect the mechanical properties of the electrodes, and for the first time it is reported that mechanical flexibility directly influences the electrochemical performance of the electrode. The importance is highlighted when processing parameters advantageous to powder materials, such as a higher heat treatment temperature, harm self-standing electrodes due to deterioration of fiber flexibility. Other strategies, such as conductive carbon addition, can be employed to improve the cell performance, but their effect on the mechanical properties of the electrodes must be considered. Rapid heat treatment achieves self-standing V2O3 with a capacity of 250 mAh g−1 at 250 mA g−1 and 390 mAh g−1 at 10 mA g−1
Due to their high energy density, Li-ion batteries have become indispensable for energy storage in many technical devices. Prussian blue and its analogs are a versatile family of materials. Apart from their direct use as an alkali-ion battery electrode, they are a promising source for templating other compounds due to the presence of carbon, nitrogen, and metallic elements in their structure, ease of synthesis, and high tunability. In this study, homogeneous iron vanadate derivatization from iron vanadium Prussian blue was successfully carried out using an energy efficient infrared furnace utilizing CO2 gas. Iron-vanadate is an inherently unstable electrode material if cycled at low potentials vs. Li/Li+. Several parameters were optimized to achieve a stable electrochemical performance of this derivative, and the effect of surfactants, such as tannic acid, sodium dodecylbenzene sulfonate, and polyvinylpyrrolidone were shown with their role in the morphology and electrochemical performance. While stabilizing the performance, we demonstrate that the type and order of addition of these surfactants are fundamental for a successful coating formation, otherwise they can hinder the formation of PBA, which has not been reported previously. Step-by-step, we illustrate how to prepare self-standing electrodes for Li-ion battery cells without using an organic solvent or a fluorine-containing binder while stabilizing the electrochemical performance. A 400 mA h g−1 capacity at the specific current of 250 mA g−1 was achieved after 150 cycles while maintaining a Coulombic efficiency of 99.2% over an extended potential range of 0.01–3.50 V vs. Li/Li+.
This Ph.D. thesis focuses on developing electrochemical energy storage devices that outperform existing lithium-ion batteries. The research investigates the design and modification of metal oxides and sulfides to enhance the electrochemical performance of commercial battery electrodes and presents the challenges met. By employing specific design strategies and derivatization methods, novel materials with unique properties are synthesized, distinct from those found in commercial batteries. For each material studied, the thesis examines the relationship between its electrochemical performance and various other material properties to address existing limitations. In the case of self-standing fibers, the influence of mechanical flexibility on electrochemical properties is analyzed. Similarly, for the conversion-type materials, the detrimental shuttling effect or electrode etching is mitigated by applying a stable coating to protect the active component from degradation. In parallel. this thesis aims to use pH-neutral syntheses and low-temperature derivatization to reduce the effect of harsh components and high-energy procedures and presents the challenges that arise from this. Additionally, this work explores complementary approaches to enhance the interface between the electrode and electrolyte after modifying the electrode material through materials engineering. These strategies are thoroughly investigated and presented as potential solutions to improve the overall performance of energy storage devices.
A suitable interface between the electrode and electrolyte is crucial in achieving highly stable electrochemical performance for Li-ion batteries, as facile ionic transport is required. Intriguing research and development have recently been conducted to form a stable interface between the electrode and electrolyte. Therefore, it is essential to investigate emerging knowledge and contextualize it. The nanoengineering of the electrode-electrolyte interface has been actively researched at the electrode/electrolyte and interphase levels. This review presents and summarizes some recent advances aimed at nanoengineering approaches to build a more stable electrode-electrolyte interface and assess the impact of each approach adopted. Furthermore, future perspectives on the feasibility and practicality of each approach will also be reviewed in detail. Finally, this review aids in projecting a more sustainable research pathway for a nanoengineered interphase design between electrode and electrolyte, which is pivotal for high-performance, thermally stable Li-ion batteries.
Hexacyanometallates, known as Prussian blue (PB) and its analogues (PBAs), are a class of coordination compounds with a regular and porous open structure. The PBAs are formed by the self-assembly of metallic species and cyanide groups. A uniform distribution of each element makes the PBAs robust templates to prepare hollow and highly porous (hetero)nanostructures of metal oxides, sulfides, carbides, nitrides, phosphides, and (N-doped) carbon, among other compositions. In this review, we examine methods to derive materials from PBAs focusing on the correlation between synthesis steps and derivative morphologies and composition. Insights into catalytic and electrochemical properties resulting from different derivatization strategies are also presented. We discuss challenges in manipulating the derivatives' properties, give perspectives of synthetic approaches for the target applications and present an outlook on less investigated grounds in Prussian blue derivatives.
