Scientific Events

(zoom lecture link comes shortly before) Current state-of-the-art lithium-ion batteries (LIBs) contain electrode materials with mostly layered structures that serve as host lattices for the reversible, electrochemical intercalation of lithium ions. The kinetics of these intercalation reactions are typically limited by the solid-state diffusion of the ions inside the lattice. Volumetric changes that accompany the (de-)insertion of ions further lead to degradation of the electrode materials. These factors contribute to the limited power and lifetime of LIBs. While some of these limitations can be mitigated by nanostructuring of the electrode material, there is a large interest in finding structural motifs that allow for intrinsically fast ion diffusion with reduced host lattice deformation, even in bulk-sized particles. In this presentation, I will highlight how interlayer properties, such as interlayer distance and interlayer chemistry, affect electrochemical ion intercalation processes in layered host materials. It is demonstrated that the presence of interlayer structural molecules can increase the accessibility of intercalating ions to the interlayer space and affect their transport properties. Increased interlayer spacing and reduced deformation during ion intercalation can lead to a change from diffusion-limited to non-diffusion limited (or pseudocapacitive) charge storage behavior, enabling favorable charge storage kinetics. The talk will give an overview of my research group’s efforts to synthesize interlayer-functionalized layered and two-dimensional materials with tailored interlayer properties towards high power intercalation electrodes and highlight the challenges regarding both materials synthesis and characterization. [more]

(zoom lecture link comes shortly before)The improvement of current and new-generation battery technologies requires the discovery of new electrode materials and the continuous development of existing ones. These are complicated processes where materials design (often aided by computational techniques), materials synthesis and characterization play an equally important role. This lecture will span different alkali-ion battery technologies and different materials chemistries (layered, polyanionic) to demonstrate the importance of an all-around approach to materials discovery and development. Particular attention will be given to thorough structural characterization techniques, using complementary probes, and to their implementation in situ, i.e. in real time during synthesis or during battery charge/discharge. [more]

Portable and stationary rechargeable batteries are within the many energy-related technologies that require fast progress within the urgent need of remediation of global climate. For example, batteries can still represent up to a third of electric vehicles emissions due to their manufacturing process and lack of end-of-life management. Developing fundamentally sustainable battery materials and electrode processing stands as a central strategy for efficient battery recycling. One essential requirement of next-generation battery technologies is the substitution of costly elements like Li and Co by widely (and more evenly) available ones like Na and Fe in the electrode materials. This implies the development of new energy storage materials, as well synthetic methods. Materials with porous and hollow morphologies are one of the promising approaches in achieving long-term stability in batteries. Such structures can buffer volumetric changes associated with many energy storage mechanisms (like conversion reactions or ion insertion), avoiding effects like aggregation, structure collapse and loss of conductivity which leads to poor electrochemical performance. Prussian blue (PB, KFe[Fe(CN)₆]) and its analogues (PBA, AM[M’(CN)₆]) are cheap, easy to synthesize, non-toxic, biocompatible, water and air-stable metal complexes. They have an intrinsic porous framework structure that allows ion intercalation with very little or no strain. Their metal centers are electroactive in both organic and aqueous media. Therefore, this class of materials is ideal for battery electrode applications, achieving high stability and capacity without the need for complex synthetic routes. The tunability of PB(A) structure and composition also makes them versatile template materials. Through different derivatization methods, PB derivatives (PBD) can be prepared. Regardless of the relatively simple structure of PB(A), PBDs present an ever-growing number of compositions that encompass metal oxides, sulfides, phosphides, carbides, hybrids (among others), and an array of morphologies from simple cubes to highly complex hollow and porous structures. Such PBD have recently demonstrated state of the art performance in catalysis and energy storage applications. This talk will give an overview of the current challenges and strategies to achieve high-performance sustainable batteries, with a focus on PB- and PBD-based electrode materials. [more]

Recovery and Utilization of Materials from electronic waste via Cryomilling to Develop Advanced Green Technologies Krishanu Biswas^#Electronic waste (e-waste) causes enormous societal and environmental impact when they enter the trash stream. It has emerged as the fastest-growing waste source in recent decades throughout the universe. The global accumulation of e-waste is expected to reach 74 Mt by 2030, nearly doubling in tonnage over this decade (2020-2030). The act of indiscriminate e-waste dumping, along with inefficient and unorthodox e-waste handling, is indisputably detrimental to economic and public health. Since e-waste has dramatically increased the impact on the environment, developing sustainable solutions for recovery and recycling is of prime importance. In this direction, the present research aims to establish an easily scalable and novel green technique to rejuvenate and effectively use metallic, ceramic and polymeric components of the e-waste by use of cryo-grinding in an ecologically responsible and energy-efficient manner. The low-temperature grinding method that breaks down PCBs all the way into nanoscaled particles, further enabling enhanced physical separation of the different base constituent materials that are the polymer, oxide, and metal. The recovered materials are easy to be beneficiated as the nanoscale particles produced from grinding are mostly single phase particles, compared to the larger particles obtained by other methods that are multiphase mixtures of various constituents. The metallic content is utilized to electrochemically selectively reduce CO₂ into distinct gaseous products, resulting in the generation of CH₄, and H₂ as main gaseous products at neutral pH. On the other hand, the extracted polymeric component is utilized to synthesize graphene/CNT using pulsed laser ablation (PLA) in a liquid media, showing promise in synthesizing high-quality graphene, which may be enhanced further by tweaking the PLA process parameters. The synthesized graphene was utilized to fabricate highly conductive electrical connections, revealing the excellent functional capacity of crystalline graphene. Polymeric content along with ceramic are being utilized for making electrical switch boards. In a nutshell, this green technique provided means of extracting main components from e-waste, via low temperature grinding, which can then be utilized to make green energy, precious materials like graphene/CNT, and other engineering applications in an ecologically responsible manner, making the process sustainable and hence, solving a global problem. [more]

The mechanisms of nucleation, growth and coalescence of voids leading to the fracture of ductile metals have been investigated for more than 50 years and modelled with increasing degrees of complexity. Nevertheless, we are still far today from a fully predictive approach, in particular in the context of the new generations of metallic alloys with advanced microstructures. Challenges remain on several fronts, for instance: the description of the statistical aspects of void nucleation, the transition into shear dominated failure mode, the physical meaning of the internal lengths entering non local models, the treatment of competing fracture mechanisms (e.g. intergranular versus ductile), etc. In this talk, recent progress made regarding the characterization and modelling of ductile fracture in Al alloys and in steel will be presented, insisting on void nucleation aspects. Topic: 9th MMELO Lecture - Prof. Thomas Pardoen Time: Febr 17, 2022 15:00h CET [more]

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In-situ transmission electron microscopy (TEM) allows researchers to analyse at the nano-scale and in ‘real time’ the electrochemical processes of the electrode materials within batteries during device operation. The active interface regions of such electrodes form solid electrolyte interface (SEI) layers during the charge and discharge cycling. The formation and movement of this functional SEI nano-interface is one of the main research fields in battery science, as it directly affects battery performance and lifetime. Of particular interest is observing the structural and chemical evolution of this lithium-rich, extremely complex polycrystalline interface. Si nanowires are attractive materials for applications such as lithium battery anodes due to their high theoretical capacity and ultra-low-cost for material sourcing and fabrication. The use of electrochemically active metals such as Sn for the growth of Si nanowires contributes to the overall specific capacity of the electrode. This study explores the phase change in both the Si nanowire metal seed head and the nanowire SEI layer during battery cycling. Our goal is to investigate the effect a chosen seed metal has on the Si electrode. We show that the lithiation/delithiation behaviour of the Sn-Si nanowire obtained using liquid cell was comparable to the result from bulk half-cell cycles and ex-situ analysis. Finally, we compare the benefits and drawbacks of liquid cell in-situ electrochemistry to cryogenic TEM analysis of the same system. Although in-situ electrochemistry TEM offers many advantages over other characterisation techniques, this analysis method is still in its infancy. [more]