Slurry Processing Research Articles

Effect of silver morphology on rheology and photopolymerization characteristics of Silver-Hydroxyapatite slurry for Vat Photopolymerization-based 3D printing process

The present work deals with the processing of HA-silver photocurable slurry to make composites using the Vat-photopolymerization process. Slurries with increasing amount of silver addition in the HA-Ag (0, 5, 10, 15%) slurry have been prepared using monomers with photo-initiators and printed successfully. Silver powder used in this study is in the form of flakes and spheres. A shear thinning behaviour of all the compositions of the slurries has been observed which is essential to fabricate defect-free parts. With increase in silver addition to 15 wt%, the viscosity decreased by around 60 % however curing depth was compromised. From SEM micrographs it was observed that HA with silver flakes showed better sintering with sintering density of 95% compared to only HA and HA with spherical silver samples.

On the use of slurry as an alternative to dry powder for laser powder bed fusion of 316L stainless steel

Laser powder bed fusion (LPBF) is a well-established additive manufacturing process for producing high-quality metal components with unparallelled design freedom. However, LPBF also has its limitations, including a limited materials palette, low productivity and high costs, mainly due to the expensive feedstock powders. These powders must meet highly stringent requirements regarding particle size (15–45μm), particle size distribution (mono-modal) and morphology (spherical), which is achievable only through expensive gas- and plasma-atomised powders. This paper investigates slurry-LPBF as an alternative to conventional dry powder LPBF. The use of slurry removes some of the stringent powder requirements by allowing deposition of smaller particles with a variety of particle morphologies. Slurry-LPBF can therefore increase the useful yield of the atomisation process and expand the materials palette for LPBF, by enabling the use of powders for which atomised variants are not commercially available. This study used 316L stainless steel powder with an average particle size <18μm. An existing slurry-LPBF machine was re-designed and re-built, allowing successful slurry processing. Two optimal parameter sets were obtained, resulting in component density of 99.4%. Tensile testing revealed an ultimate tensile strength (UTS) of 622 ± 2 MPa and an elongation at break of 66 ± 2%. These results are consistent, and fall within the range of reported values in literature for dry-powder LPBF, with the UTS being on the lower side of the range, whilst elongation at break being on the higher side.

Integrated Dual‐Phase Ion Transport Design Within Electrode for Fast‐Charging Lithium‐Ion Batteries

AbstractThe development of fast‐charging lithium‐ion batteries with high energy density is hindered by the sluggish Li+ transport and substantial polarization within graphite electrodes. Herein, this study proposes that the integrated design of liquid electrolyte and solid electrolyte, a dual‐phase electrolyte (DP‐electrolyte), can facilitate Li+ transport within a thick electrode. A 3D Li3PS4 (LPS) network is constructed within the graphite electrode to form the LPS/graphite electrode. This is achieved through the in situ conversion of the P4S16 into the LPS, a process introduced during the slurry processing. Both experimental findings and simulation outcomes indicate that this design mitigates the concentration polarization due to the improved Li+ transport capability with an overall high Li+ transference number within the electrode. With a high capacity of ≈3.1 mAh cm−2 attributed to the graphite electrode, the LiNi0.6Co0.2Mn0.2O2 (NCM622)||LPS/graphite cells demonstrate superior fast‐charging capability (4 C, 15 min, charging to ≈87.7%) and stable cycling performance (4 C, 700 cycles, ≈80% capacity retention). Furthermore, they exhibit commendable low‐temperature performance. The Ah‐level pouch cell achieves 87.5% recharge in 15 min with an energy density of ≈221.5 Wh kg−1. This work offers an alternative avenue for the advancement of fast‐charging lithium‐ion batteries with practical high energy density.

A Stable High-Potential Na7V4(P2O7)4(PO4) Cathode for Sodium-Ion Batteries Developed from a Water-Based Slurry

The sodium mixed-phosphate polyanionic compound Na7V4(P2O7)4PO4 (NVPP) is an attractive high-potential cathode material for sodium-ion batteries. In this study, a water-soluble binder, namely polyacrylic acid (PAA), was used to successfully process NVPP-based electrodes. In the absence of toxic and expensive organic solvents, the fabrication scenario of our NVPP-PAA electrode appears as a more sustainable and cost-effective approach for slurry processing and electrode production. Supported by detailed electrochemical investigations, we highlight the excellent electrochemical performance of the NVPP-PAA electrodes, which show capacity retention of ∼97% after 200 cycles at a high current density (3 C) in addition to its attractive rate capability with minimal electrode polarization up to 5 C rate.

Attaining translucency in binder/additive-free, nanograined, tetragonal 1.5 mol.% yttria-stabilized zirconia ceramics

In the quest of minimum yttria content to stabilize tetragonal zirconia system, we report the synthesis of ultrafine (∼9 nm), near-spherical, phase-pure tetragonal 1.5 mol.% yttria-stabilized zirconia (1.5YSZ) nanoparticles. The pressureless sintering process (at 1100 °C) involved of 1.5YSZ nanopowders (without any slurry processing) and did not need any binders, additives, or sintering aid to attain high-density (>98.5%) and refined grain size (∼50 nm) for the consolidated fully tetragonal 1.5YSZ nanoceramics. A promising transmittance value of 46% (at 630 nm) was obtained, making it comparable/higher in optical properties with respect to the transmittance values of existing 3 mol.% yttria-doped ZrO2 compositions. This result is credited to our synthesized phase-pure (validated via X-ray Diffraction and Raman analysis) near-spherical nanoparticles with improved tetragonality (c/a ratio = 1.439, obtained via Rietveld analysis) that paved the way for low-temperature conventional sintering for possible large-scale industrial applications.

High-frequency eddy current measurement for the characterization of graphite anode slurries in battery cell production

The global demand for lithium-ion batteries and their production in large quantities while maintaining high product quality and minimal reject rates poses new challenges for cell manufacturers. Quality control in slurry processing and electrode coating is becoming increasingly important due to high material costs. High-frequency eddy current measurement could enable characterization of the active material and reduce the reject rate by applying an inline quality measurement system. In this paper, the applicability of high-frequency eddy current measurement for characterization of graphite suspensions is investigated and its feasibility confirmed. Process parameters such as solids contents and type of graphite have been analyzed.

Understanding of Polyacrylic Acid as Binder for High Silicon Containing Anodes and Ni-Rich Cathodes

With the increased demand on electric vehicles, portable devices and energy storage systems, a great attention is being drawn to improve the energy density of lithium-ion batteries (LiBs) [1]. The commercial LiBs anodes are usually consisted of graphite-based material, which limits the energy density due to its relatively low theoretical capacities. Silicon (Si) has been recognized as an alternative anode material with its high theoretical capacity, natural abundance, and low discharge potential. Despite the above-mentioned advantages, Si undergoes a substantial volume expansion (300% approximately) during the battery operation [2]. There are some approaches to mitigate the adverse of expansion, whereas the cost and scalability of these techniques are the bottlenecks to solve this issue [3]. In this work, we focus on maintaining the structural integrity, along with the coordination of Li as functional binder which could be an effective solution to the abovementioned challenges.In addition to the energy density and capacity targets, considering more environmentally friendly approaches is also one of the key topics for battery manufacturing. Aqueous processing of the anodes is already state-of-the-art whilst, the cathode has its own challenges to be overcome. Ni-rich transition oxide active materials, such as LiNi0.8MN0.1Co0.1 (NMC811), are attractive for high-capacity target applications. Due to the high reactive surface of the active material, during the slurry processing, NMC811 reacts with water, which leads to Li+/H+ exchange [4]. Thus, the slurry results in high pH which can corrode the aluminum foil current collector and cause poor capacity due to Li loss. The advantage of using polyacrylic acid (PAA) is to employ COOH, in which the leached Li+ can bond to the backbone. Hence, the pH of slurry is maintained on desirable coating range and the capacity loss can be reduced due to the proposed aqueous processing.In this study, we explore the utilization of a well-known polymer, polyacrylic acid, as binder for both negative and positive electrodes. On the anode, PAA is functionalized with Li+ and used LiPAA prior to electrode production. It is highly crucial to observe how the dynamics of Si and LiPAA impacts the anode performance during the cycling. To comprehend this, post mortem, scanning electron microscopy (SEM) was performed to detect the positioning and concentration of Si on pristine and cycled anodes. On the cathode side, the focus is to utilize the leached Li+ during the slurry processing by having PAA as binder. This technique has been already successfully implemented by our group on the research pilot scale [5]. The idea is to make pH stable slurry without using any additional acid, in conjunction with creating in situ functional binder (LiPAA). Deep understanding of functional binders is to serve as a guide for the rational design of Si-electrode and aqueous NMC811 cathodes for LiBs.

Understanding and Comparing the Stability of Water- Versus NMP-Based Tin(IV)Sulfide Electrodes Using Post-Mortem Analysis

The market for lithium-ion batteries (LIBs) has experienced a tremendous growth since 1991, when the first LIB was commercialised by Sony, and it is expected to grow even further. The reason for this upward trend is on the one hand the improvement in performance, specifically in energy density and cyclability, and on the other hand the world’s increase in energy demand. LIBs are now able to power not only small electronic devices but also electric vehicles and stationary energy storage systems.In addition to the increased need for batteries with high energy densities, environmental aspects must also be considered. Firstly, commercial LIBs contain critical raw materials (CRM) such as Li, Co, and graphite which are often concentrated in a few areas of the world and are sometimes mined using techniques which exploit both humans and the planet. Secondly, the use of toxic chemicals such as N-methyl-2-pyrollidone (NMP) in electrode manufacturing raises concerns on the degree of sustainability of the product. Furthermore, in order to reduce the CO2 emissions and achieve climate-neutrality by 2050, the EU (BATT4EU) has set goals regarding energy densities, battery life time and safety. Desired values for gravimetric and volumetric energy densities for Generation 3 LIBs are considered 350-400 Wh/kg and 750-1000 Wh/l respectively for 2000+ cycles. These energy values can be achieved by either developing cathodes with higher voltage and/or by developing cathodes and anodes with higher specific capacity. The latter approach together with sustainability aspects are addressed in this work. Tin(IV)sulfide (SnS2) has been investigated in the last few years as one of the most promising anode materials for Li-ion batteries due to its high theoretical specific capacity of 1209 mAhg-1 compared to commonly used graphite (372 mAhg-1). However, its theoretical reversible capacity is 644 mAhg-1 due to the conversion of SnS2 to Li2S and Sn in the first discharge. Furthermore, SnS2 can be processed using water as a solvent in place of previously mentioned NMP. This way, not only the electrochemical performance, but also the environmental friendliness, as well as costs during fabrication can be improved.This study focusses on the optimization of water-based slurry processing using SnS2 as active material, and water-soluble binders such as sodium carboxymethylcellulose (Na-CMC) and styrene butadiene rubber (SBR) in comparison to NMP-based electrodes using Polyvinyl difluoride (PVDF) as a binding agent.In this work, four different electrode compositions were investigated, namely SnS2/C45/CMC:SBR(1:1) in a 90/5/5 ratio and a 80/10/10 ratio, as well as a comparative system consisting of SnS2/C45/PVDF in the same ratios as the previous electrode. All electrode compositions showed an initial specific capacity of ~550 mAh/g, however the cycling stability was in the order of H2O-80:10:10 > H2O-90:5:5 > NMP-80:10:10 > NMP-90:5:5 (Figure 1), with the best water-based electrodes reaching 80% state-of-health (SoH) after 200 cycles.In order to understand the degradation mechanisms occurring during cycling and to elucidate the impact of H2O- and NMP-based processing on electrochemical performance, techniques such as Raman, SEM, XRD, XPS, and EIS were performed on pristine electrodes, on electrodes after first discharge (formation cycle), as well as on samples at 80% SoH. Furthermore, in-situ dilatometry was conducted to measure the linear change in length of the electrodes in the direction perpendicular to the electrode surface during cycling. Changes in crystal structure, morphology, surface chemistry (i.e. SEI formation), interface and charge transfer resistance, and volume expansion were correlated with the electrochemical performance.(Attached: Figure 1: Comparative graph of galvanostatic cycling with potential limitation (GCPL) of water- and NMP-based electrodes with varying ratios of active material/conductive agent/binder showing the development of capacity and coulombic efficiency as a function of cycle number) Figure 1

Tuning the cathodic-anodic electrochemical transition in lithium iron borate by optimizing synthesis parameters, anionic doping and potential window

This report presents a comprehensive investigation into the transformation of a high-capacity LiFeBO3 cathode material to an anode material by fluorine doping. The structural and electrochemical studies of LiFeBO3 are investigated in detail with respect to synthesis temperature, anion doping, and specific potential windows. Lowering the synthesis temperature preserves the monoclinic structure of the material, allowing a higher specific capacity close to 200 mAh g−1 within the potential window of 1.5–4.0 V. However, higher synthesis temperatures leads to the degradation of the monoclinic structure, subsequently reducing the specific capacity to 114 mAh g−1, even though the slurry processing is carried out in an inert atmosphere. The introduction of 10 % fluorine doping induces a complete transformation of the monoclinic structure into a vonsenite-type phase. Surprisingly, the vonsenite-type material exhibits a drastically reduced cathodic capacity of 11 mAh g−1 within the aforementioned potential window. Nevertheless, it displays promising anodic behavior when operated below 2.5 V, demonstrating its potential for application as a conversion-type anode in Li-ion batteries. The crystal structure of the composite material is found to contain LiF and Li–B–O phases, contributing to an extended cycle life compared to undoped carbon-coated Fe3BO5. The cyclability of the anode material is further enhanced by the use of sodium carboxymethyl cellulose (Na-CMC) as a binder and fluoroethylene carbonate (FEC) as an electrolyte additive. Overall, this study furnishes valuable insights into the structural modifications and electrochemical performance of a LiFeBO3 cathode transformed into a fluorine-doped anode material. These findings contribute to the synthesis strategies for novel electrode materials, opening up new avenues for the design and development of advanced Li-ion battery systems with improved performance and longevity.

Investigating Mechanisms Leading to Enhanced Performance of Carbon-Coated Si Anodes By Chemical Vapor Deposition Method

Prior research on carbon-coated silicon (Si@C) for Si-based lithium-ion batteries have shown improved electrochemical performance upon coating. However, the underlying mechanisms responsible for the enhancement in performance have not been fully explored and are typically attributed to the protective influence of the carbon coating around the Si particles as well as the improved electronic conductivity of the electrode. In this work, we investigate the contribution of coating on the processing of the electrodes as well as on the formed solid electrolyte interphase (SEI). Si@C particles were prepared by chemical vapor deposition (CVD) technique to achieve a homogeneous carbon layer on the Si surface. The influence of coating time as well as processing temperature was investigated. X-ray photoelectron spectroscopy (XPS), neutron reflectivity (NR) measurements, and transmission electron microscopy (TEM) reveal the coating characteristics such as its extremely thin nature, ~2.5 nm, allowing us to rule out the protective function of carbon coating to prevent Si volume expansion as the governing mechanism for the improved electrochemical behavior. Instead, Raman mapping of the electrodes reveal a uniform distribution of Si and carbon conductive additive, indicating that the coating on the Si particles can facilitate slurry processing which yields to more homogeneous electrodes. Consequently, this leads to the commonly reported improved electronic connections within the electrodes as supported by electrochemical impedance spectroscopy (EIS) data. Furthermore, SEI studies using XPS reveal similar SEI characteristics of the Si electrodes after cycling in half and full cell format. In summary, we assign the improved performance of Si@C on the beneficial effect of carbon coating on the processing of Si electrodes, but not on the electrochemical passivation.

Connecting structure and rheology of silicon/carbon supraparticle-based lithium-ion battery anode slurries

Due to the globally increasing demand for lithium-ion-batteries of high energy density, novel silicon-based materials of hierarchical structure are investigated as a potential replacement for conventional anode materials such as graphite. Since industrial process technologies cannot keep up with the development of new formulations, such approaches should be suited as ”drop-in” methods to the existing manufacturing processes. In this study, spray-dried silicon-based supraparticles of hierarchical structure are investigated regarding their suitability for industrial slurry processing under harsh mechanical conditions. The chosen strategy is to connect the structural integrity of the supraparticles with their time-dependent rheological behavior in anode slurries to provide methods for a mechanical characterization tailored to supraparticles. Apart from questions of battery processing, this study also provides general guidance on the rheology of supraparticle dispersions, which has been little studied so far. Structural kinetic models, experimentally determined thixotropic relaxation times, and a differential effective medium approach tailored for supraparticles are used herein. With this developed rheological toolset, a strong indicator of the mixing fraction of supraparticles and their primary particles inside full anode slurries is presented and the deagglomeration dynamics of the supraparticle structure in shear flow are resolved.

Additive manufacturing of Al2O3 ceramic core with applicable microstructure and mechanical properties via digital light processing of high solid loading slurry

Ceramic cores are essential intermediate mediums in casting superalloy hollow turbine blades. The developing of additive manufacturing (AM) technology provides a new approach for the preparation of ceramic cores with complex structure. In this study, alumina oxide (Al2O3) ceramic cores with fine complex geometric shapes were fabricated by digital light processing (DLP) in high resolution. The maximum solid content of 70 vol% of ceramic slurry was adopted in the printing process, which is important for the regulation of deformations and mechanical properties. The effects of the printing parameters, including exposure intensity, printing layer thickness and sintering temperature on the microstructures and mechanical properties of printed samples were investigated. The decrease of residual stress and similar shrinkage in X, Y, and Z directions could be obtained by adjusting the printing parameters, which are crucial to prepare complex ceramic cores with high quality. Besides, the flexure strength and open porosity of ceramic cores reached 34.84 MPa and 26.94%, respectively, which were supposed to meet the requirement of ceramic cores for the fabrication of superalloy blades.

Phase field model of microstructure formation during cooling slope slurry generation of novel Al-15Mg2Si-4.5Si composite

The present study discusses the development of a two-dimensional phase field model of semi solid microstructure evolution of the novel Al-15Mg2Si-4.5Si composite during cooling slope rheoprocessing. The superheated melt of the said composite undergoes partial solidification during its shear flow over the slope free surface, prior to get collected within the isothermal slurry holding furnace. Seed undercooling based nucleation model is adopted in the present PF model to simulate slurry microstructure of the composite. Experimentally determined cooling rate values are considered to simulate slurry microstructure for different process conditions. Micrographs of melt samples collected during experimentation establishes the developed PF model as an accurate microstructure prediction tool for the composite slurry. Apart from morphological features such as size and degree of sphericity values of the evolving primary Mg2Si and α-Al grains, the model predictions includes melt temperature as well as solid content at any given instant of slurry processing.

Numerical Investigation of the Local Shear Rate in a Twin‐Screw Extruder for the Continuous Processing of Li‐Ion Battery Electrode Slurries

The mixing step for electrode slurry preparation in the manufacture of batteries is highly relevant because it directly affects the downstream production processes and the performance of the battery cells. In this work, a study of the flow behavior and material strain in a twin‐screw extruder is carried out to analyze its efficiency for continuous battery slurry processing. Here, individual elements of the extruder screw are simulated using the smoothed particle hydrodynamics method. Based on the resulting flow profiles, a dimensionless analysis is used to validate the calculations. Hence, the local shear rate and pressure profiles are evaluated for different screw geometries. The effects of the screw design and process setup are discussed, to accordingly improve the mixing process.

Rational Design of a Bifunctional Peptide Exhibiting Lithium Titanate Oxide and Carbon Nanotube Affinities for Lithium-Ion Battery Applications

Phage display is employed as a method for identifying polypeptides that bind to lithium-ion battery materials, specifically lithium titanate oxide (LTO) and multiwalled carbon nanotubes (MWCNTs). Output/input assays are used as a quantitative measure to narrow down the strongest binding polypeptides from several peptides selected through biopanning. Negatively stained transmission electron microscopy is used to verify that a phage presenting a particular LTO or MWCNT binding peptide sequence colocalizes with the respective material. Heterologous expression allows for ample polypeptides to be grown and purified using a peptide expression vector. Isothermal titration calorimetry in conjunction with alanine scanning enables determination of the pertinent residues involved in LTO binding and yields a dissociation constant of 3.41 μM. A rationally designed bifunctional peptide exhibiting LTO and MWCNT binding domains is subsequently validated to exhibit both LTO and MWCNT affinities and is incorporated as a binding agent in LTO coin-type electrochemical cells where the bifunctional peptide demonstrates stability at high cycle rates and potential as an alternative to non-specific binding agents for aqueous slurry processing of lithium-ion battery electrodes.

Precisely controlling the surface roughness of silica nanoparticles for enhanced functionalities and applications

HypothesisColloids with rough topography demonstrate more complex interactions and tremendous potential in industrial applications. However, relevant studies suffer from a range of challenges, including cumbersome synthesis, complex characterization, and very limited functionalities. A comprehensive study of rough nanoparticles can not only broaden our understanding of rough colloids, but also help to avoid some of their detrimental impacts in real life (e.g., clogging and pumping failures in slurry processing). ExperimentsA facile route to precisely control the surface roughness of silica nanoparticles and a highly efficient method to characterize the surface roughness were developed respectively. The fabricated particles can be applied for the immobilization of metal nanostructures; their cytotoxic effects and the capability to be used as a drug-delivery vehicle were also evaluated. FindingsModifying the addition time of precursors (i.e., TEOS and MPTMS) can precisely control the surface roughness of silica nanoparticles. The developed characterization method based on TEM observations allows statistical analyses on a large number of particles, and therefore features very reasonable accuracy. These rough particles behave like microporous materials, where the loading strategy is closely related to their surface roughness. Medium rough particles are promising carriers of metal nanostructures, while the roughest ones are excellent candidate for doxorubicin delivery to cancer cells.

Green biomass processing to lower slurry viscosity and reduce biofuel cost

Sustainable fuels for industries that cannot be easily electrified, like aviation and marine, will be crucial to achieving a carbon neutral economy. Processing wet solids through a process like hydrothermal liquifaction to produce upgradeable bio-oil is one pathway that could transform high moisture waste into a fuel. This work pioneers two green processing pathways to produce a biomass feedstock for liquefaction that is far less viscous at higher solids loadings than traditional slurries. This decrease in viscosity could significantly improve the profitability of producing fuels through slurry-based conversion processes. Natural biological degradation of corn stover before grinding has been shown to lower slurry viscosity by a factor of three and torrefaction has been shown to produce slurries that are 150x less viscous than the original material. Additionally, new insight has been gained into the critical physical and chemical parameters that impact slurry viscosity. Common parameters in slurry processing, like the average particle size, shear rate, and solids loadings clearly control viscosity, and these results are confirmed for biomass. Additionally, new physical parameters like aspect ratio and sphericity, as well as chemical parameters like extractives content, non-structural sugars, and zeta potential have been shown to impact and be good predictors of slurry viscosity and processability.

High-Energy-Density and Long-Lifetime Lithium-Ion Battery Enabled by a Stabilized Li2O2 Cathode Prelithiation Additive.

Lithium-ion batteries (LIBs) typically suffer from large irreversible capacities caused by active lithium loss during formation of a solid electrolyte interface (SEI) at the anode side. Cathode prelithiation with preloaded additives has emerged as an effective strategy to solve the above issue. With ultrahigh theoretical capacity, Li2O2 serves as an excellent cathode prelithiation additive, whereas poor ambient stability limits its further development. In this study, we report a surface protection strategy to enable ambient processing of the Li2O2 additive. Li2O2 is well confined in poly(methyl methacrylate) (PMMA) nanofibers (P-Li2O2) via electrospinning, which exhibits greatly enhanced ambient stability compared with the unprotected one. Notably, when P-Li2O2 is preloaded in LiNi0.5Co0.2Mn0.3O2 cathodes (NCM-P-Li2O2), PMMA nanofibers remain stable during cathode slurry processing but readily dissolve in electrolytes and expose Li2O2 for effective electrochemical oxidation. Fabrication of P-Li2O2 allows systematic investigation of prelithiation behavior in full cells (NCM-P-Li2O2 cathodes paired with Si/Graphite anodes) and its impact on the electrochemical performance. Rational tuning of the prelithiation degree provides guidance for optimizing the amount of the cathode additive, which brings appealing cell lifetime and energy density.

Advanced Balancing of Next-Generation Lithium-Ion Batteries: Prelithiation of a-Silicon Nanowires Using Excess Lithium Positive Electrodes

Sustainability and high energy are key requirements for the next-generation lithium-ion batteries (LIBs) to match the rapidly growing electric vehicle (EV) market. On the positive electrode, lithium-rich layered oxides (LRLOs) are ideal candidates for next-generation LIBs since they are possibly free of the critical element cobalt and relatively rich in manganese. Additionally, LRLOs promise outstanding specific capacity (>250 mAh g-1), which is superior to any other cathode material reported so far.On the negative electrode side, silicon-based materials are highly interesting.1 With their very high specific capacity and slightly higher de-/lithiation potential they can overcome intrinsic challenges of graphite limiting the energy density and high-rate capability of current Li-ion cells.2 Additionally, silicon is also more abundant and – in contrast to graphite and cobalt – not listed as a critical raw material by the EU and US.3,4 Certainly, both materials still face challenges, e.g., voltage and capacity fading due to structural transformation in LRLOs, or particle cracking and excessive SEI formation in Si-based anodes, which can be possibly overcome through modifications of the materials and, especially, design of the electrolyte.5,6 Herein, we present the achievement of excellent electrochemical performance of Li-ion cells with Co-free LRLO cathodes (Li1.2Ni0.2Mn0.6O2, LRNM) offering a capacity retention of >75% after 200 cycles when paired with an a-Si-NW anode, and even 81% after 1,000 cycles in LRNM||graphite cells. In both cases a cathode pre-lithiation additive, introduced during electrode slurry processing, was successfully used as a cycle life enhancer.7 References Armand, M. et al. Lithium-ion batteries – Current state of the art and anticipated developments. J. Power Sources 479, (2020).Asenbauer, J. et al. The success story of graphite as a lithium-ion anode material – fundamentals, remaining challenges, and recent developments including silicon (oxide) composites. Sustain. Energy Fuels (2020).Bobba, S., Carrara, S., Huisman, J., Mathieux, F. & Pavel, C. Critical Raw Materials for Strategic Technologies and Sectors in the EU - a Foresight Study. European Commission (2020).Olivetti, E. A., Ceder, G., Gaustad, G. G. & Fu, X. Lithium-Ion Battery Supply Chain Considerations: Analysis of Potential Bottlenecks in Critical Metals. Joule 1, 229–243 (2017).Wu, F. et al. Reducing Capacity and Voltage Decay of Co-Free Li1.2Ni0.2Mn0.6O2 as Positive Electrode Material for Lithium Batteries Employing an Ionic Liquid-Based Electrolyte. Adv. Energy Mater. 10, (2020).Stokes, K. et al. Influence of Carbonate-Based Additives on the Electrochemical Performance of Si NW Anodes Cycled in an Ionic Liquid Electrolyte. Nano Lett. 20, 7011–7019 (2020).Solchenbach, S. et al. Lithium oxalate as capacity and cycle-life enhancer in LNMO/Graphite and LNMO/SiG full cells. J. Electrochem. Soc. 165, A512–A524 (2018).

Pilot-scale annual production of Scenedesmus almeriensis using diluted pig slurry as the nutrient source: Reduction of water losses in thin-layer cascade reactors

The microalga Scenedesmus almeriensis was produced using diluted pig slurry as the sole nutrient source during one year using a 30 m2 thin-layer cascade photobioreactor located outdoors. Evaporation contributes significantly to the water requirements of microalgae production; approximately 1000 L of water are required to produce 1 kg of microalgal biomass. The aim of this study was to assess the potential of plastic covers to avoid or minimise water evaporation in open photobioreactors. The N–NH4+ concentrations at the inlets ranged from 40 to 100 mg L−1, depending on the experimental run. These values could not be increased because of the dark colour and turbidity of the pig slurry. The biomass productivity of the system was 17.6, 18.8, 23.4, and 17.3 g m−2·day−1 in winter, spring, summer, and autumn, respectively. Covering the reactors led to a decrease in biomass productivity that ranged from 8.5 to 16.9% depending on the season. However, water evaporation was reduced by 24.9–42.0% depending on the season. In summer, covering the reactors reduced the amount of water evaporated from 6.3 to 3.6 L m−2·day−1. In a theoretical 1 ha production facility, this would represent 2700 L of water saved per day. Overall, the processing of pig slurry using microalgae is challenging because of their variable nutrient concentration, colour and turbidity. Covering the reactors with inexpensive commercial plastics could significantly reduce the water requirements of the system.