Silicon-based Materials Research Articles

In Situ Copper Coating on Silicon Particles Enables Long Durable Anodes in Lithium-Ion Batteries.

Addressing the significant obstacles of volume expansion and inadequate electronic conductivity in silicon-based anode materials during lithiation is crucial for achieving a long durable life in lithium-ion batteries. Herein, a high-strength copper-based metal shell is coated in situ onto silicon materials through a chemical combination of copper citrate and Si-H bonds and subsequent heat treatment. The formed Cu and Cu3Si shell effectively mitigates the mechanical stress induced by volume expansion during lithiation, strengthens the connection with the copper substrate, and facilitates electron transfer and Li+ diffusion kinetics. Consequently, the composite exhibits a reversible specific capacity of 1359 mA h g-1 at 0.5 A g-1 and maintains a specific capacity of 837 mA h g-1 and an 83.5% capacity retention after 400 cycles at 1 A g-1, surpassing similar reports on electrochemical stability. This facile copper plating technique on silicon surfaces may be used to prepare high-performance silicon-based anodes or functional composites in other fields.

Composition of silicon jointly doped with impurity atoms of gallium and phosphorus

In this work, the morphology and composition of the silicon surface are experimentally studied using a scanning electron microscope, X-ray phase analysis, and various peaks in the Raman spectra. The spectral characteristics of silicon doped with impurity atoms of phosphorus and gallium have been studied. It was shown, that in the silicon lattice simultaneously doped with gallium and phosphorus atoms impurity atoms created binary complexes. Experimental determination of the concentration of gallium and phosphorus atoms made it possible to reveal a significant increase in the concentration of gallium, in comparison with its fundamental solubility in silicon. It is shown that a sufficiently large concentration of such elementary cells can lead to a significant change in the electrophysical parameters of silicon, i.e. the possibility of obtaining a new silicon-based material.

Research progress on silicon-based materials used as negative electrodes for lithium-ion batteries

People’s need for energy is growing as science and technology advance, and finding effective ways to store and use energy has become crucial in today’s world. Due to its effectiveness, environmental friendliness, and renewable nature, lithium-ion batteries (LIBs) are now a hot topic in study. However, traditional lithium-ion battery anode is usually graphite material, energy density limitations, its theoretical specific capacity is relatively low, difficult to meet the growing demand for high energy density. Moreover, graphite anode also has the disadvantages of limited multiplication performance, low first charge/discharge efficiency, and high charge/discharge platform voltage. Silicon-based materials have great potential for application in LIBs anode due to their high energy density, low de-embedded lithium potential, abundant resources, low cost, and good electrochemical properties. As a result, the materials based on silicon in LIBs are the main topic of this research. First, this paper, summarizes the advantages and challenges of the current silicon-based materials. Then, several forms of current silicon-based anode materials exist, including: silicon-carbon composites and alloying of silicon, are explored. Finally, improvement strategies for silicon-based materials are highlighted.

Effect of soft denture liners on complete denture treatments: A systematic review.

This systematic review examined the effectiveness of soft denture relining (SDR) materials. A comprehensive search of MEDLINE, Cochrane Library, and ICHUSHI was conducted up to July 26, 2020. Target outcomes were patient satisfaction, oral health-related quality of life (OHRQOL), masticatory ability (MA), denture functional duration, residual ridge resorption (RRR), and microbial contamination. An organization specializing in literature searches performed the reference searches, and two reviewers independently selected the literature sources, extracted the data, and assessed the risk of bias. The reviewers resolved any disagreements concerning the assortment of literature sources through discussion. SDR included acrylic- and silicone-based materials, which were evaluated separately. Reviewers selected 7, 5, 11, 1, 4, and 6 studies to assess patient satisfaction, OHRQOL, MA, functional duration, RRR, and microbial contamination, respectively. The results confirmed that SDR improved patient satisfaction, OHRQOL, MA, and RRR. However, the functional duration of SDR material is shorter than that of hard denture relining (HDR) or acrylic resin material. Furthermore, SDR material is more susceptible to microbial contamination in the long term. The risk of bias for the included studies tended to be high because of specific issues (difficulty in blinding SDR versus HDR). For patients who wear complete dentures, SDR often provides beneficial outcomes such as pain reduction and recovery from MA. However, caution should be exercised regarding their use owing to insufficient functional duration and the possibility of microbial contamination during long-term use.

Modification strategy of silicon-based anode for lithium-ion battery

Lithium-ion batteries play an important role in dealing with the energy crisis, and their high energy density, fast charging, and discharging performance, long life, environmental protection, safety, and adaptability make them obvious advantages in the field of energy storage. The anode is an important component in lithium-ion batteries, and the selection and performance of anode materials directly affect the key indicators such as energy density, cycle life, and safety performance of the battery. As a new type of anode material, silicon-based anode material has the advantages of high specific capacity, which can greatly increase the storage capacity of the battery, and good fast-charging performance, which ensures the rapid charging and discharging of the battery. This paper firstly introduces three kinds of silicon-based anode materials with wide application potentials in many industries: nanometer Si, Si-C composite, and Si-metal composite, and then introduces three silicon anode modification strategies, namely binder, pre-lithiation, and electrolyte additives, and their application effects. Through these strategies, the advantage of the high specific capacity of silicon anode can be fully utilized, thus improving the energy density and cycle stability of lithium-ion batteries. Finally, the future applications and development directions of silicon-based materials and their modification strategies are summarized.

Influence of surface ablation on plasma and its interaction with electromagnetic field

Surface ablation significantly affects the distribution of plasma in high-speed flow and the characteristics of its interaction with electromagnetic fields. Considering the mechanism of ablation and ejection on the surface of hypersonic vehicle, the participation of ablation products in the plasma generating process in the flow field, the conduction mechanism of mixed ionized gas containing alkali metal and the electromagnetic dynamics mechanism, the coupled calculation method of high-speed flow/plasma/electromagnetic field with alkali metal ablation is established by solving the three-dimensional thermochemical non-equilibrium flow governing equation with electromagnetic source term, the electric field Poisson equation and the magnetic vector Poisson equation. Combined with the common ablation and pyrolysis process of carbon-carbon materials and silicon-based phenolic resin materials, the mechanism and law of the interaction between surface ablation and electromagnetic field on the hypersonic plasma sheath under various conditions are systematically studied. The results show that the ablation effect affects the plasma distribution in the flow field, which is affected by the ablation mass ejection rate and the mass proportion of alkali metal. When the alkali metal content is high, the alkali metal ionization reaction is dominant, and the electron number density can increase by 1–2 orders of magnitude. The influences of different materials on plasma are different. The mass ejector ratio of silicon-based phenolic resin is larger, and the molar concentration of CO<sup>+</sup> and C<sup>+</sup> produced by ionization is close to that of NO<sup>+</sup> and <inline-formula><tex-math id="Z-20240520210947">\begin{document}${\mathrm{O}}_2^+ $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20231733_Z-20240520210947.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20231733_Z-20240520210947.png"/></alternatives></inline-formula>, which cannot be ignored. Alkali metal in ablative material can significantly improve the control effect of magnetohydrodynamics. With the increase of the proportion of alkali metal, the coupling effect of electromagnetic field increases, and the relationship between them is nonlinear. When the speed is low, the ionization degree of air itself is low and the coupling effect of electromagnetic field is weak. But the efficiency of “improving the electromagnetic effect by ablation of alkali metal” is higher.

Recent progress and challenges in silicon-based anode materials for lithium-ion batteries

This review highlights the importance of silicon-based anodes in lithium-ion batteries, emphasizing their improved performance through modifications involving binders, coatings, composites, and electrolytes.

Crack-induced abrupt capacity degradation in commercial LiNi0.8Co0.1Mn0.1O2 (NCM811)/SiO x -graphite pouch batteries.

Reasons for abrupt capacity fading in commercial LiNi0.8Co0.1Mn0.1O2 (NCM811)/SiO x -graphite pouch batteries were evaluated using electrochemical methods. These approaches consist of charge and discharge curves, differential curves and electrochemical impedance spectroscopy (EIS), and some advanced verification techniques constituting scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The predominance testament concerning capacity attenuation through experimental verification after the battery is disassembled proves that the silicon-based anode material deteriorates further, bringing about a significant number of cracks with the progression of cycles. In addition, electrolyte enters into the cracks, generating the excessive growth of the solid electrolyte interface (SEI) and the expansion of impedance, which eventually causes the failure of conductive networks, dilemma of ion transmission and increment in polarization, ultimately contributing to lithium dendrites.

Low-cost silicon cutting waste reused as a high-power-density silicon-based anode.

With the rapid development of electric vehicle technology, commercial graphite anodes (theoretical capacity of 372 mA h g-1) of lithium-ion batteries cannot meet the needs for high power density. Silicon has high theoretical capacity (4200 mA h g-1), low working voltage (about 0.4 V vs. Li/Li+), rich resources and environmental friendly nature; hence, it is regarded as a potential negative electrode material. During repeated charging and discharging, silicon particles continuously pulverize, which leads to the volume expansion of electrode materials (up to 400%) and a decrease in conductivity. In this study, high-purity nano-silicon was prepared via a calcination-ball milling-pickling process with low-cost silicon cutting waste (SiCW) as a raw material to meet the needs of lithium-ion batteries for high-purity and nano-scale silicon-based anodes. At the same time, silicon@graphite nanocomposites with different mass ratios were prepared via a low-cost industrialized ball-milling process. The easy intercalation and softness of the graphite layer structure realized the coating and joining of nano-silicon, which improved the conductivity of nano-silicon and restrained the rapid degradation of cycling performance caused by the expansion and pulverization of the silicon-based anode. Adopting low-cost raw materials and industrialization-based preparation processes can effectively control the production cost of silicon-based anode materials and lay a solid foundation for their practicality.

Recent Advances in Plasma Etching for Micro and Nano Fabrications of Silicon-based Materials: A Review

The demands for precision machining of silicon-based materials are growing in various modern applications, including micro-electro-mechanical systems (MEMS), micromotors, sensors, bioelectronics, medical implants, and microfluidic devices. Towards the miniaturization and...

Two step pyrolysis synthesis method of graphite-enhanced Nano-Si/Pitch composite as long cycle life anode for lithium-ion batteries

Energy storage devices have become the dominant power source in various fields due to their capacity, lifespan, and eco-friendliness. However, there is a need to develop new energy storage devices with higher energy and power density to meet increasing energy demands. Silicon-based anode materials have considerable potential for developing long-lasting, high-capacity energy storage devices, specifically lithium-ion batteries. However, the practical use of these batteries faces challenges like significant volume variations, silicon instability during charging and discharging, and restricted conductivity. This work used silicon nanoparticles from waste industrial solar cells and mixed them with pitch derived from coal tar in a tetrahydrofuran (THF) solvent to form a homogenous Si@Pitch nanocomposite. Pitch-derived carbon helps hold the silicon particles together, reducing the detrimental effects of volume expansion. It acts as a matrix that accommodates the structural changes in silicon during lithiation and delithiation. The Pyrolyzed Si@Pitch-2:1 nanocomposite electrode developed through an efficient two-step pyrolysis technique demonstrated outstanding performance. When charged at a rate of 500 mA·g−1 over 200 cycles, it showed a high discharge capacity of 1524 mAh·g−1, with an average coulombic efficiency of 99.8% and a discharge capacity retention of 75.7%. Combining silicon nanoparticles and pitch derived from recycled industrial waste contributes to the impressive results. This efficient synthesis method can improve the anode materials used in lithium-ion batteries.

Metallic B2Si monolayer as a flexible anode material for Li, Na and K-ion batteries: A first principles study

Silicon-based 2D materials have garnered significant attention as outstanding anodes of alkali metal ion batteries (MIBs); nevertheless, the poor electrical conductivity and mechanical property have severely hindered their practical application. In this work, we conducted a detailed first principles calculation to examine a newly-developed 2D silicon-boron binary compound (named B2Si) as the anode of MIBs. The B2Si anode harbors the intrinsic metallicity and exhibits low Li/Na/K diffusion barriers of 0.26, 0.14 and 0.09 eV, which makes a great contribution to the high rate performance. The storage capacities for Li/Na/K are predicted to be 1908.57, 583.48 and 431.97 mA h/g, respectively, superior to the commercial graphite anode. Moreover, the B2Si anode has good mechanical property and structural flexibility, which could avoid destroying its structure on the metal ion intercalation/deintercalation process. These fascinating features render the B2Si monolayer an exceptional anode of MIBs.

Accelerating the Development of New Silicon-Based Anode Materials

In this work we have demonstrated the feasibility of using thin film systems as a steppingstone to accelerate the development of commercially relevant silicon-based anode materials for Li-ion batteries. Understanding new materials in conventional particle-based electrode systems is often complex. Lithium and electrolyte interact not only with the active material particles, but also with the different supporting components of the electrode, leaving it difficult to directly assess the electrochemical contribution of the active material. This is further complicated by the electrochemical behavior of such electrodes also being strongly dependent on processing conditions, like casting and drying procedures. Additionally, it is often also a challenge to synthesize such materials in particle form with the required chemical composition and monodispersity in the first place. Therefore, it would be highly beneficial to study and screen new anode materials without having to assume and assess these different factors. That is of particular importance during the optimization stage of the chemical composition for the active material, for which a significant number of samples is typically needed. Thus, evaluating the material in a thin film system is a simple and reproducible method of determining a material’s potential as a future anode material.Such thin films of active materials can reliably be made with a large range of thicknesses, compositions, element combinations and coatings, using multiple flexible and reproducible thin film deposition techniques available. In the present work, we have investigated silicon-based materials made by PECVD and sputtering: pure silicon and sub-stoichiometric versions of silicon nitride, silicon carbide, and silicon phosphide (SiNx, SiCx, SiPx). For evaluation of the applicability of the thin film model system, in several cases we have also compared the results to particles of the same material with similar chemical composition synthesized via a free space CVD process [1].Preliminary evaluation shows good agreement between results for thin film systems compared to what is known for particles of the same material. SiNx particles show good agreement with thin film results where a high nitrogen content decreases the capacity, while increasing the stability due to the formation of a stabilizing matrix around the active silicon [2]. Differences in the differential capacity analysis of similar materials in particle and thin film forms demonstrates the greater complexity in interpreting the data from the more intricate particle-based systems. SiCx is known to react in a similar fashion as SiNx where its coulombic efficiency and capacity decreases with increasing carbon-content, while its stability has been seen to increase due to a similar stabilizing matrix [3]. Reference s : [1] H. F. Andersen et al., ECS Trans., vol. 62, no. 1, pp. 97–105, 2014.[2] A. Ulvestad et al., ACS Nano, vol. 15, no. 10, pp. 16777–16787, 2021.[3] X. D. Huang et al., RSC Adv., vol. 8, no. 10, pp. 5189–5196, 2018.

Improving SiOx Electrode Performance in Pressurized Pouch Cells with a Ceramic Coated Separator

The global electric vehicle (EV) landscape, driven by environmental concerns, has propelled the demand for high-capacity battery materials. Silicon-based anode materials have emerged as promising candidates due to their remarkable capacity. However, the inherent challenge lies in their substantial volume expansion during operation, exceeding 300%, which causes structural instability within the electrode.To counteract this issue, a direct compression method is employed to mitigate the anode's volumetric expansion, ensuring sustained adhesion between active materials and current collectors. This approach promotes consistent electrical connectivity and augments capacity retention. Nevertheless, excessive pressure can detrimentally affect separators with limited mechanical resilience, resulting in pore constriction. This constriction impedes the efficient flow of electrolytes between the separator and electrode, leading to premature lithium depletion.In our study, we compressed SiOx electrodes using Ceramic Coated Separator (CCS). CCS's unique combination of mechanical reinforcement, improved wetability, and enhanced ionic conductivity played a pivotal role, ultimately contributing to the overall improvement in electrode performance. We employed digital-twin simulations, utilizing the Finite Volume Method (FVM), to investigate the influence of CCS on various aspects. Digital-twin simulations involve creating a computational replica of the real object's geometry, allowing us to replicate its behavior and characteristics in a virtual environment, thereby enabling a detailed and accurate assessment of CCS effects. This included analyzing the enhancement of mechanical properties, such as the evaluation of von Mises stress and effective stiffness. Furthermore, we explored how CCS impacted the deformation of separators under pressure and closely monitored the movement of lithium ions within them.The findings underscore the successful integration of CCS into SiOx electrodes, resulting in a substantial improvement in life and performance under pressure conditions. This research contributes valuable insights to the advancement of battery technology, particularly in the context of EVs, by addressing critical challenges associated with silicon-based anode materials.

In-Situ Convertible Amorphous Silicon Nitride (SiNx) Anode: Resolving the Long-Term Cyclic Instability of Silicon

Silicon (Si) has shown its promises as anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high theoretical capacity1. However, its practical application has been impeded by the severe cyclic instability caused by a large volume change during (de) lithiation. Recently, a new family of silicon-based anode materials called “in-situ convertible-type anode materials” has emerged to resolve the cyclic instability of silicon.2,3 This family includes sub-stoichiometric oxides, nitrides, and carbides of silicon (SiAx, where A = N, C, O). The working principle of these materials follow two mechanisms: (1) irreversible conversion and (2) reversible alloying/dealloying. During initial lithiation, the conversion reaction occurs, forming Si-Li nanodomains inside a stable Li-conductive matrix denoted as LiySixA (A=N, C, O). In the subsequent cycles, the Si-Li nanodomains reversibly alloying/dealloying with Li, while the Li-conductive matrix ensures stable cycling and good rate capability. Such composition mitigates the challenges associated with Si’s large volume change ensuring long-term cyclic stability.In this study, we demonstrate our approach on the development of silicon-rich, sub-stochiometric, amorphous silicon nitride (SiNx) nanoparticles, as an in-situ convertible-type anode material and its long-term cyclic performance for LIBs. In this approach, the SiNx nanoparticles are produced via the decomposition of silane gas in the presence of ammonia using an industrially scalable, free space reactor (FSR), which is developed and customized in our research institute (IFE) (Fig. 1a). Proper proportions of silane and ammonia gases are introduced into the reactor, leading to the nucleation and growth of SiNx nanoparticles. The synthesized SiNx nanoparticles exhibited Si-rich domain and amorphous structure with particle size between 100 nm - 200 nm (Fig. 1b), as confirmed by SEM, TEM and XRD characterizations. The presence of nitrogen in silicon dominated composition is revealed by energy dispersive electron spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR). The scalability and reproducibility of the FSR synthesis method makes it a promising approach for the industrial production of SiNx for advance anode materials for LIBs.The electrochemical performance of the synthesized SiNx anode is evaluated by galvanostatic cycling and electrochemical impedance spectroscopy. The electrochemical performance of the SiNx performed on the electrodes with the active mass loading of 0.987 mg/cm2 and cycled at C/5 rate has preserved its capacity about 852 mAh/g after around 600 cycles. As seen from Fig. 1c, the improved cyclic stability of the SiNx compared with pure silicon indicates that the Li-conductive matrix plays crucial role in stabilizing the anode. The authors emphasize the need for further investigation and collaboration, particularly in advance characterization, to better understand the composition and mechanisms of the Li-conductive matrix in the SiNx anode. Such detailed understanding can significantly benefit the conversion-type anode materials for their widespread use in future LIB technologies.References Zuo, X., Zhu, J., Müller-Buschbaum, P. & Cheng, Y.-J. Silicon based lithium-ion battery anodes: A chronicle perspective review. Nano Energy 31, 113–143 (2017).Ulvestad, A. et al. Stoichiometry-Controlled Reversible Lithiation Capacity in Nanostructured Silicon Nitrides Enabled by in Situ Conversion Reaction. ACS Nano 15, 16777–16787 (2021).Kilian, S. O. et al. Active Buffer Matrix in Nanoparticle-Based Silicon-Rich Silicon Nitride Anodes Enables High Stability and Fast Charging of Lithium-Ion Batteries. Advanced Materials Interfaces 9, 2201389 (2022). Figure 1

Pre-Lithiation of Silicon-Based Anode Materials: Concepts and Realization

The capacity in lithium ion battery (LIB) relies on active lithium, i.e., lithium-ions and electrons, which separately shuttle between the electrodes during charge and discharge. Given state-of-the art active materials for anodes, loss of active lithium and capacity remains a major challenge during LIB operation, in particular in the first charge/discharge cycle due to electrolyte decomposition and formation of solid electrolyte interphase (SEI).Pre-lithiation, i.e., artificial increase in active lithium amount into the battery is a promising strategy to counteract active lithium loss. Electrochemical(1) and chemical(2,3) methods of pre-lithiation can be distinguished. While electrochemical methods are based on the use of an external power source, the driving force of the chemical reaction is a negative change in the Gibb´s free energy which in the case of pre-lithiation is provided by the use of highly reactive chemical compounds (e.g. lithium-organic complex solutions or lithium metal). The use of lithium metal allows for a wide range of technological processes, including lamination of lithium foil, gas-phase deposition, application of lithium melts or suspensions containing lithium powder. In this contribution, various concepts of pre-lithiation will be discussed from experimental and up-scaling point of view on the example of Si-based anodes.(1) Haneke, L.; Pfeiffer, F.; Bärmann, P.; Wrogemann, J.; Peschel, C.; Neumann, J.; Kux, F.; Nowak, S.; Winter, M.; Placke, T., Insights into Electrolytic Pre‐Lithiation: A Thorough Analysis Using Silicon Thin Film Anodes. Small 2022, 2206092.(2) Adhitama, E.; Bela, M. M.; Demelash, F.; Stan, M. C.; Winter, M.; Gomez‐Martin, A.; Placke, T., On the Practical Applicability of the Li Metal‐Based Thermal Evaporation Prelithiation Technique on Si Anodes for Lithium Ion Batteries. Advanced Energy Materials 2023, 13 (3), 2203256.(3) Bärmann, P.; Mohrhardt, M.; Frerichs, J. E.; Helling, M.; Kolesnikov, A.; Klabunde, S.; Nowak, S.; Hansen, M. R.; Winter, M.; Placke, T., Mechanistic Insights into the Pre‐Lithiation of Silicon/Graphite Negative Electrodes in “Dry State” and After Electrolyte Addition Using Passivated Lithium Metal Powder. Advanced Energy Materials 2021, 11 (25), 2100925.

Investigating the Rheological Properties of Silicon/Carbon (Si/C) Composite Supraparticles Used in Lithium-Ion Battery Anodes

Silicon-based active materials emerged as a very promising replacement for graphite in lithium-ion battery (LIB) anodes [1]. The unfavorable issue of particle pulverization due to inherent volume changes during lithiation / delithiation, which is still a problem hindering the full-scale implementation of silicon anodes in LIB, can be avoided by utilizing nanosized active materials. Our new approach of spray drying the nanometer-sized building blocks to micrometer-sized supraparticles enables additional improvement for Si-based anodes [2]. This approach, however, creates new hurdles for processing and quality control since a stable processing of the supraparticles to final electrodes is a key criterion for enhanced LIB performance.Figure 1: Schematic representation of the deagglomeration/breakage behavior of Si/C supraparticles in a slurry as a factor of particle motion/shear [3].In order to find indicators for supraparticle breakage early in the process chain of Si/C anode manufacturing, we conducted detailed rheological investigations on the slurry level. We parameterized structural kinetic models for slurries prepared with mixtures of supraparticles and nanosized building blocks particles to simulate supraparticle breakage (Fig. 1). With this approach, two indicators were found. First, the thixotropic response showed a strong dependence on the ratio between the spherical supraparticles and the nanosized building blocks. Second, the viscosity decreased with increasing percentage of the fractal-shaped nanosized particles. While further investigating this unexpected effect on viscosity, additional rheological characterizations of the components gave interesting insights into the overall rheological properties of hierarchically structured particle dispersions. The component carbon black and the nanosized/agglomerated active material were individually characterized in aqueous binder solutions to determine their individual contributions to the rheological properties of the full slurry. Here, the focus was laid on shear thinning and thixotropy and how the observed properties relate to the well-known rheology of hard spheres [4].In conclusion, a deeper understanding of anode slurry rheology enables tailored formulations and process conditions. Moreover, our methodology is applicable to other energy-related materials that are a key part of formulation science and particle technology. References Xiao, L.; Sehlleier, Y. H.; Dobrowolny, S.; Orthner, H.; Mahlendorf, F.; Heinzel, A.; Schulz, C.; Wiggers, H., Si-CNT/rGO Nanoheterostructures as High-Performance Lithium-Ion-Battery Anodes, ChemElectroChem 2, 1983-1990 (2015).Amin, A.; Loewenich, M.; Kilian, S. O.; Wassmer, T.; Bade, S.; Lyubina, J. et al, One-Step Non-Reactive Spray Drying Approach to Produce Silicon/Carbon Composite-Based Hierarchically Strucutured Supraparticles for Lithium-Ion Battery Anodes, J. Electrochem. Soc. 170,020523 (2023).Watermann, J.; Amin, A.; Wiggers, H.; Segets, D.; Özcan, F., Connecting structure and rheology of silicon/carbon supraparticle-based lithium-ion battery anode slurries, In Powder Technology, manuscript submitted.De Kruif, C.G.; van Lersel, E. M. F.;Vrij, A., Hard sphere colloidal dispersions: Viscosity as a function of shear rate and volume fraction, J. Chem. Phys. 83, 4717-4725 (1985). Figure 1

Molecular Layer Deposition of Metal Phosphonates: A New Class of Hybrid Coating Layers

Atomic layer deposition (ALD) is a vapor phase thin film deposition technique where materials can be grown atom-by-atom in a layer-by-layer manner. Over the course of just few years, it has become to be one of the most sophisticated methods of producing high quality thin films with control at the sub-nanometer scale. Molecular layer deposition (MLD) is a variant of ALD where molecular fragments are intentionally built into the growing films.MLD is one of the techniques which allows to grow organic-inorganic hybrid materials with thickness control at sub-nanometer level.1 Nowadays, organic-inorganic hybrid materials have been found to attract a lot of attention because of their distinctive properties obtained by combining chemical and physical properties of organic and inorganic segments. Numerous hybrid materials have been synthesized by MLD over the time; however, commercial application of those materials are still a challenge due to their hydrolytic instability in most cases. Perhaps, the most widely used hybrid materials in our daily life is polysiloxanes, or commonly called as silicones, a silicon-based hybrid material . The hydrolytic stability of Si-C and Si-O-Si bonds is the main reason of their practical usage as hybrid materials. Similarly, organophosphorus compounds are an important class of materials because they offer several alternatives to silicon-based linking in the field of hybrid materials. Most of the hybrid films produced by MLD technique contain C, O, N, and S elements in the organic part. Hybrid materials containing P-atoms are yet to be explored by MLD.Among others, metal phosphonates, in particular, an important class of organophosphorus compound, show promising application covering from ion-exchange, proton conductors, catalysts, sensors, membranes, fire retardants etc.2,3 Examples of metal-organic compounds based on phosphonic acid derivatives can be found in literature stemming several decades back. Phosphonates are widely considered as an effective metal chelating ligand. Their dianionic tetrahedral form (RPO3 -2) enables different modes of coordination with metal which is not possible with the extensively used contemporary carboxylate (RCO2 -2) ligands. P-O-M and P-C linkages are quite stable, and therefore organophosphorous compounds with phosphonate ligands have been used to produce thermally and chemically stable hybrid materials by several other techniques.4 Here, we report the synthesis of novel aluminum phosphonate hybrid layers obtained with MLD method. Trimethyl aluminum (TMA) has been used as the metal source and two different novel phosphonate ester precursors with two different organic groups have been used to grow the aluminum phosphonate layers. The growth characteristics of the layers have been studied by in situ ellipsometry, whereas the as-grown films have been characterized with different ex situ techniques like FTIR, XPS, XRD, SEM and AFM. As-deposited metal phosphonate layers show superior thermal (>500 0C in air) and complete water stability. We believe, this kind of metal phosphonate layers may open up new opportunities in the field of organic-inorganic hybrid coatings for various applications. Meng, X. J. Mater. Chem. A 5, 18326–18378 (2017).Goura, J. & Chandrasekhar, V. Chem. Rev. 115, 6854–6965 (2015).Zhu, Y.-P., Yuan, Z.-Y. & Alshareef, H. N. ACS Materials Lett. 2, 582–594 (2020).Vioux, A., Le Bideau, J., Mutin, P. H. & Leclercq, D. New Aspects in Phosphorus Chemistry IV 145–174 (Springer Berlin Heidelberg, 2004).

Investigating the Impact of Si/C Supraparticles Size Distribution on the Lifetime of Li-Ion Battery Half-Cells

The development of high-performance anodes for lithium-ion batteries (LiBs) with robust cycling stability has become a prominent area of research. In our recent study (Amin et al. 2023), we demonstrated that adopting a hierarchical structuring strategy via spray drying can significantly improve the cycle life of silicon-based anode materials in contrast to their nanoparticle building blocks (4 wt.% of compounding carbon). This method enhances the structural stability of the anode, thereby improving cyclic performance and paving the way for the development of high-capacity LIBs.However, beyond phenomenological proof of principles, understanding the effect of supraparticles size distribution on electrochemical performance is of great significance for making Si-based active materials ready for the LiBs industry. Therefore, we systematically investigated the correlations between supraparticle median sizes/size distributions and other supraparticle properties such as their BET surface area, slurry rheology, coated layer quality, and the electrochemical Coulombic efficiency of half-cells. These findings revealed that supraparticles with large median sizes are stable against processing as compared to small size supraparticles as can be seen from atomic force microscopic (AFM) images of coated layers in Fig 1a. It is also discovered that large supraparticles enhance the 3rd cycle Coulombic efficiency (2 formation cycles) of Li-ion half cells at 0.5 C as shown in Fig.1b. However, there exists an optimal median size/size distribution above which the Coulombic efficiency and cycling stability of the supraparticles in half-cells starts to decrease.In short, supraparticles exhibit properties (e.g., high layer stability, low surface reactions) that outperform those of individual nanoparticles. Understanding the role of supraparticle sizes in generating anodes with a hierarchical structure demonstrates great promises towards tailored materials for enhanced LiB performance. This enables us to further unravel process-structure-property relationships and understand the physics behind the improved electrochemical performance of supraparticles. Publication bibliography Amin, Adil; Loewenich, Moritz; Kilian, Stefan O.; Wassmer, Theresa; Bade, Stefan; Lyubina, Julia et al. (2023): One-Step Non-Reactive Spray Drying Approach to Produce Silicon/Carbon Composite-Based Hierarchically Structured Supraparticles for Lithium-Ion Battery Anodes. In J. Electrochem. Soc. DOI: 10.1149/1945-7111/acb66b. Figure 1

High Precision Coulometry and Calorimetry Measurements of Side Reactions for Si/NCA and G/NMC811 Cells

Side reactions taking place at both anode and cathode can be investigated via different methods. Common methods include the high precision coulometry [1-3] and the isothermal calorimetry [4, 5]. In this study, pure silicon anode (70 wt%) Si/NCA cells and pure graphite G/NMC811 cells are investigated via the methods mentioned above. These measurements include voltage holds and charge and discharge endpoint slippage analysis, which is described in [6]. Glazier et al. [4] already showed that after sufficient time, the heat flow during a voltage hold is equivalent to the side reactions taking place. The aim of this study is to investigate the dependency of side reaction currents and parasitic heat on different voltages and temperatures. In addition, their behaviour during the transient phase caused via relaxation processes and edge effects [7] comparing silicon and graphite materials.The cells voltage was held at different state-of-charge (SOC) conditions, low, medium, and high as well as at different temperatures. At the beginning and at the end of the experiment, check-ups were performed to compare the capacity loss and to analyse the endpoint slippage. During the measurements, the heat flow and the leakage current of the cells were measured simultaneously.The preliminary results show that for the low and for the high SOCs, a strong opposing transient phase is present at the beginning of the voltage hold. The strong transient phase is expected for silicon-based materials due to their high relaxation characteristics, meaning also higher leakage currents for this material. Additionally, it was found that the different pre-histories of the cells influence the amount of leakage current measured. Meaning that the actual side reaction current is only achieved after edge effects and relaxation processes cease, which can take a long time for pure Si anodes, up to 1000 hours at 25°C. Moreover, the transient phase of the thermal and the electrical signals was correlated for the different materials.The study of side reactions for lithium ion cells is investigated in the project “ExZellTUM III”, funded by the German Federal Ministry of Education and Research (BMBF) under grant number 03XP0255. [1] Smith, A.; Burns, J.; Dahn, J.: A high precision study of the coulombic efficiency of Li-ion batteries, In: Electrochemical and Solid-State Letters 13, pp. A177, 2010 [2] Smith, A.; Burns, J.; Xiong, D.; Dahn, J.: Interpreting High Precision Coulometry Results on Li-ion Cells, In: Journal of The Electrochemical Society 158, S. A1136– A1142, 2011 [3] Burns, J. C.; Jain, G.; Smith, A. J.; Eberman, K. W.; Scott, E.; Gardner, J. P.; Dahn, J. R.: Evaluation of effects of additives in wound Li-ion cells through high precision coulometry, In: Journal of The Electrochemical Society, 158 (3), A255-A261, 2011 [4] Glazier, S. L.; Downie, L. E.; Xia, J.; Louli, A. J.; Dahn, J. R.: Effects of fluorinated carbonate solvent blends on high voltage parasitic reactions in lithium ion cells using OCV isothermal microcalorimetry, In: Journal of The Electrochemical Society, 163 (10), A2131-A2138, 2016 [5] Glazier, S. L.; Odom, S. A.; Kaur, A. P.; Dahn, J. R.: Determining parasitic reaction enthalpies in lithium-ion cells using isothermal microcalorimetry, In: Journal of The Electrochemical Society, 165 (14), A3449-A3458, 2018 [6] Streck, L.; Roth, T.; Keil, P.; Strehle, B.; Ludmann, S.; Jossen, A.: A comparison of voltage hold and voltage decay methods for side reactions characterization, In: Journal of The Electrochemical Society, 170, 040520, 2023 [7] Roth, T.; Streck, L.; Graule, A.; Niehoff, P.; Jossen, A.: Relaxation effects in self-discharge measurements of lithium-ion batteries, In: Journal of The Electrochemical Society, 170, 020502, 2023