Wet Ball Milling Research Articles

Enhancing Stability of High-Concentration β-Tricalcium Phosphate Suspension for Biomedical Application.

We propose a novel process to efficiently prepare highly dispersed and stable Tricalcium Phosphate (β-TCP) suspensions. TCP is coupled with a polymer to enhance its brittleness to be used as an artificial hard tissue. A high solid fraction of β-TCP is mixed with the polymer in order to improve the mechanical strength of the prepared material. The high solid fractions led to fast particle aggregation due to Van der Waals forces, and sediments appeared quickly in the suspension. As a result, we used a dispersant, dispex AA4040 (A40), to boost the surface potential and steric hindrance of particles to make a stable suspension. However, the particle size of β-TCP is too large to form a suspension, as the gravity effect is much more dominant than Brownian motion. Hence, β-TCP was subjected to wet ball milling to break the aggregated particles, and particle size was reduced to ~300 nm. Further, to decrease sedimentation velocity, cellulose nanocrystals (CNCs) are added as a thickening agent to increase the overall viscosity of suspension. Besides the viscosity enhancement, CNCs were also wrapped with A40 micelles and increase the stability of the suspension. These CNC/A40 micelles further facilitated stable suspension of β-TCP particles with an average hydration radius of 244.5 nm. Finally, β-TCP bone cement was formulated with the suspension, and the related cytotoxicity was estimated to demonstrate its applicability for hard tissue applications.

Clay-Based Hydrogels as Drug Delivery Vehicles of Curcumin Nanocrystals for Topical Application.

The poor water solubility of a significant number of active pharmaceutical ingredients (API) remains one of the main challenges in the drug development process, causing low bioavailability and therapeutic failure of drug candidates. Curcumin is a well-known Biopharmaceutics Classification System (BCS) class IV drug, characterized by lipophilicity and low permeability, which hampers topical bioavailability. Given these premises, the aim of this work was the design and the development of curcumin nanocrystals and their incorporation into natural inorganic hydrogels for topical application. Curcumin nanocrystals were manufactured by the wet ball milling technique and then loaded in clay-based hydrogels. Bentonite and/or palygorskite were selected as the inorganic gelling agents. Curcumin nanocrystal-loaded hydrogels were manufactured by means of a homogenization process and characterized with respect to their chemico-physical properties, in vitro release, antioxidant activity and skin permeation. The results highlighted that the presence of bentonite provided an increase of curcumin skin penetration and simultaneously allowed its radical scavenging properties, due to the desirable rheological characteristics, which should guarantee the necessary contact time of the gel with the skin.

Facile Preparation of Nitrogen-Doped Carbon Spheres with Wrinkled Cage-Supported Single-Atom Copper Catalysts for Selective Oxidation of Glycerol to Formic Acid

Selective conversion of the surplus glycerol (GLY) to a hydrogen storage material, formic acid (FA), in heterogeneous catalytic systems is still challenging in the catalysis community. Herein, nitrogen-doped carbon spheres with wrinkled cage-supported single-atom Cu catalysts (Cu/NCSWCs) were prepared by wet ball milling of 5,5′-diamino-3,3′-bis(1H-1,2,4-triazole) (DABT) and copper nitrate with hydrothermal carbon-encapsulated dendritic fibrous nanosilica (DFNS) as the hard template in methanol. After the removal of DFNS, structural characterization revealed that single copper atoms with four nitrogen coordination were successfully immobilized on NCSWCs (CuN4/NCSWCs), which is attributed to the fact that DABT could act as the chelating agent and nitrogen source. Furthermore, due to their unique CuN4 structures and large meso/macropore volumes derived from their wrinkled cages, CuN4/NCSWCs exhibited the highest catalytic activity and selectivity in oxidation of GLY to FA using H2O2 as the oxidant. In contrast, only C3 and C2 products were produced when O2 was used as the oxidant. Electron paramagnetic resonance measurements indicated that H2O2 and O2 can be activated to generate ·OH and ·O2– over CuN4/NCSWCs, respectively. Experimental studies and density functional theory calculations revealed that ·OH adsorbed on CuN4 structures reacted with GLY to produce FA through consecutive steps involving dehydrogenation, oxidation, and oxidative cleavage. Moreover, CuN4/NCSWCs also exhibited high catalytic stability during eight consecutive catalytic runs.

Effects of Typical Solvents on the Structural Integrity and Properties of Activated Kaolinite by Wet Ball Milling.

The influence of organic solvents on the structural integrity and properties of activated kaolinite were compared and analyzed via characterization techniques and molecular dynamics (MD) simulation. The results revealed that the organic intercalators can be easily inserted into the interlayer spaces of activated kaolinite within a short time of the wet ball milling. The DMSO intercalated kaolinites maintained structural integrity due to the high intercalation rate and the excellent buffering effect against the crushing force of milling during the delamination/exfoliation process. The delaminated layers of the DMSO-kaolinite complex exhibited a high specific surface area of 99.12 m2/g and a low average thickness of 35.21 nm. The calculated elastic properties of the organo-kaolinite complex manifested the intercalation of DMSO into a kaolinite interlayer, which could improve the compressibility and structural integrity of kaolinite nanosheets. The DMSO-kaolinite complex was easier to peel off when compared to the other organic intercalators due to its more intercalated molecules.

Effects of Wet and Dry Micronization on the GC-MS Identification of the Phenolic Compounds and Antioxidant Properties of Freeze-Dried Spinach Leaves and Stems

Micronization is an emerging technology used in food production, in which the size of particles is reduced to microns in the processing of plant raw materials and by-products, thus making it an interesting research topic. Spinach stems are by-products of spinach leaf processing, but there is little information regarding their processing and possible reuse. In this study, wet and dry ball mill micronization, in combination with freeze drying, was used to process spinach stems and leaves to obtain functional powders. The color and particle size of the micronized spinach leaf and stem powders were evaluated. The antioxidant activity (AA) of the powders and phenolic compounds present in them were determined using GC-MS analysis. The results obtained showed that the dry micronization of leaves and stems resulted in smoother and brighter powders than wet micronization. Significantly smaller particle sizes were achieved using the dry micronization of the leaves and stems (Dv50 = 19.5 and 10.1 µm, respectively) rather than wet micronization (Dv50 = 84.6 and 112.5 µm, respectively). More phenolic compounds, such as o-coumaric acid and gallic acid, were extracted from the dry-micronized powders. The dry micronization of the stems significantly increased the total phenolic content, and the AA of these powders was also increased. These findings demonstrate that spinach leaves and stems subjected to dry micronization can be valuable functional components of food.

Preparation and Electrochemical Properties of Carbon-Coated LiMn0.6Fe0.4PO4 Cathode Material for Lithium-Ion Batteries

The LiMn x Fe1−x PO4/C (x = 0.5, 0.6, and 0.7) cathode materials for lithium-ion batteries were synthesized by polyethylene glycol (PEG) 400 as the carbon source via a combination of wet ball-milling and high-temperature solid-state reaction. The analysis results of X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) indicate that the as-prepared LiMn0.6Fe0.4PO4/C sample has a single-phase orthorhombic olivine structure, and the majority of particle sizes range from 100 to 200 nm with a ∼2–3 nm carbon coating layer. The electrochemical measurements demonstrate that the obtained LiMn0.6Fe0.4PO4/C composite possesses preferable Li-ion storage properties, and the discharge capacity of 137.7 mAh g−1 at 1 C rate, which is 83.6% of that at 0.1 C rate. The composite also exhibits outstanding cycling stability, with a capacity retention of 98.2% after 100 cycles at 0.2 C rate. And the differential capacity analysis (dQ/dV) reveals that the dominating degradation of LiMn0.6Fe0.4PO4/C is caused by the Mn2+ /Mn3+ redox capacity loss which is located at ∼4.12/3.96 V, whether during the charge or discharge process. Moreover, the LiMn0.6Fe0.4PO4/C sample delivers excellent high-temperature performance (45 °C), with improved reversible capacity and capacity retention of 148.7 mAh g−1 and 99.3% after 80 cycles at 0.5 C rate, respectively.

Alpha-Germanium Nanolayers for High-Performance Li-ion Batteries.

The exfoliation of tridimensional crystal structures has recently been considered a new source of bidimensional materials. The new approach offers the possibility of dramatically enlarging the library of bidimensional materials, but the number of nanolayers produced so far is still limited. Here, we report for the first time the use of a new type of material, α-germanium nanolayers (2D α-Ge). The 2D α-Ge is obtained by exfoliating crystals of α-germanium in a simple one-step procedure assisted by wet ball-milling (gram-scale fabrication). The α-germanium nanolayers have been tested as anode material for high-performance LIBs. The results show excellent performance in semi-cell configuration with a high specific capacity of 1630 mAh g-1 for mass loading of 1 mg cm-2 at 0.1 C. The semi-cell was characterized by a constant current rate of 0.5 C during 400 cycles and different scan rates (0.1 C, 0.5 C, and 1 C). Interestingly, the structural characterization, including Raman spectroscopy, XRPD, and XPS, concludes that 2D α-Ge largely retains its crystallinity after continuous cycling. These results can be used to potentially apply these novel 2D germanium nanolayers to high-performance Li-ion batteries.

A comparative study on the photocatalytic activity and formation mechanism of nanostructured Cu2ZnSnS4 prepared by thermal and mechano-thermal methods

In this paper, a nanostructured Cu2ZnSnS4 (CZTS) was synthesized from elemental constituents through two simple methods: thermal and mechano-thermal. The thermal analysis was applied to determine the appropriate heat treatment conditions. Wet ball milling was employed in mechano-thermal synthesis to obtain a uniform activated powder, and the optimum conditions were investigated. The X-ray diffraction (XRD) and Raman results confirmed the formation of kesterite structure CZTS after annealing the mixture at 550 °C for 1 h in thermal synthesis, while the annealing temperature for CZTS formation is reduced to 410 °C in mechano-thermal synthesis. For mechano-thermally synthesized sample, the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM) results showed the agglomerated powders with average particle sizes of 123 and 139 nm, respectively. The surface and optical properties of samples were compared through Brunauer-Emmett-Teller (BET), diffusion reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. DRS results demonstrated considerable absorbance over the entire range of visible light wavelengths with bandgap energies of about 1.48–1.51 eV. The photocatalytic activities of synthesized samples, degradation kinetics and mechanisms, and the effect of SnO2 phase formation have been investigated through photodegradation of methylene blue (MB) dye under visible light irradiation. The optimum mechano-thermally synthesized sample as the photocatalyst led to 94% degradation after 120 min. Mechanism explained by scavenger studies revealed that holes were the main reactive radicals responsible for the degradation process.

A Comparison of the Fine-Grinding Performance between Cylpebs and Ceramic Balls in the Wet Tumbling Mill

This study investigated the effect of grinding media on the fine-grinding performance in the wet tumbling mill. Comparative experiments between cylpebs and ceramic balls were conducted in a laboratory wet ball mill under various conditions, such as different total masses, total surface areas, and total numbers. The results indicated that ceramic balls produce a slightly smaller instantaneous breakage rate than cylpebs due to their small bulk density at the same charge volume. However, a larger instantaneous breakage rate can be obtained by ceramic balls with the same total mass due to the larger surface area. According to experiments related to the total surface area and total number of ceramic balls, it was found that the fine grinding of ceramic balls also needs to meet a certain break force, which is mainly determined by the diameter of the ceramic balls. Moreover, two models were developed to use ceramic balls instead of cylpebs as fine-grinding media in the wet tumbling mill based on the ball size and the ratio of the total mass of cylpebs. Cylpebs can be replaced by ceramic balls with 1.16–1.75 times the diameter of cylpebs, taking up only 76%–83% of the total weight of cylpebs. When the charge volume of cylpebs is between 20% and 35% in the wet ball mill, cylpebs can be replaced by ceramic balls of the same single mass, with the total weight of the ceramic balls being only 74%–77% of that of the cylpebs.

Interface structure and corrosion protection of hybrid particles prepared via surfactant- and silica-assisted wet ball milling

The paper proposes a simple way to simultaneously modify iron particles with both silica and surfactant molecules, which involves wet ball milling of iron with silica glass and surfactants (stearic and n-perfluorononanoic acid). The structure of interfaces in the as-modified particles was analyzed by XPS and NEXAFS spectroscopies. Silica glass is finely powdered and its mechanical rubbing into ductile iron particles induces chemical transformations at interfaces between iron and silica with the formation of various products. Surfactants are then adsorbed on silica-enriched particle surfaces. In the case of stearic acid, the surfactant is attached through the hydrogen bonds between the carboxyl and silanol groups of the outermost hydrated layer, whereas n-perfluorononanoic acid is adsorbed through carboxylates formed with iron atoms in the outer silicate layer. The angle-dependent NEXAFS analysis has shown predominantly up-right arrangement of the surfactant molecules with respect to the particle planes. Hybrid layers of silica and n-perfluorononanoic acid exhibit better corrosion resistance than those comprised of only SiO2 or only n-perfluorononanoic acid, which contrasts to stearic acid molecules providing proper anticorrosive efficiency alone.

Influence of multi‐walled carbon nanotube content on electromagnetic wave absorption and mechanical properties of carbon nanotube/polyamide 12 composite

AbstractThree‐dimensional printing has proven to be a convenient and effective method for manufacturing structured electromagnetic wave (EMW) absorbers with adjustable EMW absorption characteristics. In this study, composites of multi‐walled carbon nanotube (MWCNT) and polyamide 12 (PA12) were prepared via wet dispersion and mechanical ball milling followed by melt extrusion. The effects of different levels of MWCNT content on the EMW absorption and mechanical properties of the MWCNT/PA12 composite were examined. Within the MWCNT content from 7 to 12 wt%, the flexural strength of the composite increases with the addition of MWCNT, and the impact strength, tensile strength, and volume resistivity of the composite decrease with the addition MWCNT. With regard to the best impedance matching, when sodium dodecylbenzene sulfonate was used as the dispersant, the lowest reflection loss observed herein for the MWCNT/PA12 composite was −20 dB, which was achieved with an MWCNT content of 10 wt%. Furthermore, the composite exhibited superior mechanical properties. The tensile and flexural moduli of the composite were 18.85% and 33.97% higher than those of pure PA12, respectively. Moreover, the MWCNT/PA12 composite was proven to be a high performance modeling material suitable for fused deposition modeling. And the tensile strength, flexural modulus, and impact strength of the printed samples can reach 94.45%, 92.94%, and 85.51% of those of the injection‐molded samples, respectively.

Effect of Catalyst Aggregate Size on the Mass Transport Properties of Non-Noble Metal Catalyst Layers in PEMFC Cathodes

Non-noble metal catalysts (NNMCs) are regarded as ultimate promising alternative to the high-cost Pt-based catalysts required to catalyze the oxygen reduction reaction (ORR) in the cathode of proton exchange membrane fuel cells (PEMFCs). Indeed, novel syntheses established in recent years have led to NNMCs with initial fuel cell performances comparable to those of Pt-based materials [1]. However, due to their intrinsically lower ORR-activity compared to Pt, NNMC cathodes catalyst layers (CLs) require much higher loadings than those of Pt-based (≈ 4 mgNNMC·cm−2 vs. ≤ 0.3 mgPt·cm−2, respectively) to achieve similar performances. This makes NNMC CLs much thicker (up to ≈ 100 μm) than conventional Pt-based ones, which results in additional mass transport issues [2] that prevent them from reaching the high current densities at high potentials required for automotive applications.In this context, our group recently proposed a novel synthesis [3] that yields NNMCs with a high initial ORR-activity in PEMFC tests (≈ 10 A·g−1 at 0.8 V in H2:O2 at 80 °C, 1.5 barabs, and 100% relative humidity) but poor mass transport properties due to the NNMC’s large particle size. In this study, we have efficiently reduced the aggregate size of this NNMC type from the > 2 μm in Ref. [3] to ≈ 100 nm by substituting the dry ball-milling (BM) originally used to mix the catalyst precursors with wet BM (i.e., in the presence of a solvent). The electrochemical behavior of both kinds of NNMCs was studied through rotating ring disk electrode (RRDE) voltammetry measurements, which revealed significant enhancement in the ORR limiting current of the NNMC with a smaller particle size. Moreover, 3 times higher H2O2 yield (≈ 5% to ≈ 15%) was observed for both catalyst types when lowering their RRDE-loading from 0.5 to 0.1 mgNNMC·cm-2 while keeping the homogenous film quality for both catalyst at low loadings. Subsequently, PEMFC tests were conducted for both kinds of NNMCs with different loadings (1 or 4 mgNNMC·cm-2) using both O2 and air as the cathode reactant feeds. The mass transport overpotential (ηtx) was then assessed by subtracting the polarization curves recorded in O2 vs. air (and correcting for the shift in reversible potential caused by the concomitant change in the O2 partial pressure) [4]. As displayed in Figure 1, increasing the loading of the dry-BM sample resulted in a larger mass transport over-potential, while in the case of wet-BM sample ηtx barely changed as a consequence of the larger loading. Overall, this reduction of the catalyst’s aggregate size led to a ≈ 75 mV improvement in ηtx at low loading, which became more than 2 times larger (≈ 175 mV) in the case of the CLs with a high loading, thus confirming the enhanced mass transport properties of wet-BM NNM-catalyst layer. Acknowledgments: The authors acknowledge the financial assistance of the Swiss National Science Foundation through Sinergia grant CRSII5_18033.

Energy-Size Reduction of Magnetite-Calcite Binary Mixture in a Laboratory Wet Conical Ball Mill

Energy-Size Reduction of Magnetite-Calcite Binary Mixture in a Laboratory Wet Conical Ball Mill

Optimization for preparing Bi1.68Pb0.32Sr1.75Ca1.85Cu2.85O10+y powders by wet ball milling

Superconducting Bi1.68Pb0.32Sr1.75Ca1.85Cu2.85O10+y (Bi-2223) powders were prepared by a conventional solid-state reaction using hand grinding and wet ball milling. The effects of the ball milling and sintering times on the phase evolution were examined by x-ray diffraction and magnetic susceptibility measurements. Single-phase Bi-2223 powders with a superconducting transition temperature of about 108 K were optimally prepared by wet ball milling for 20 h and sintering at 867 °C for 80 h. Finding these optimal preparation conditions were crucial for mass producing high-quality single-phase Bi-2223 precursor powders with a much lower cost of energy. Furthermore, we found that ball milling led to thinner grains than hand grinding.

Transformation of Ritonavir Nanocrystal Suspensions into a Redispersible Drug Product via Vacuum Drum Drying

The present study explored vacuum drum drying (VDD) as potential drying technique for the solidification of crystalline ritonavir nanosuspensions prepared by wet-ball milling. In detail, the impact of drying protectants (mannitol, lactose, trehalose) added to the ritonavir nanosuspension was assessed in dependence of the drum temperature with respect to processibility via VDD, resulting intermediate powder properties, remaining nanoparticulate redispersibility and crystallinity. A clear impact of the glass transition temperature (Tg) of the drying protectant on the redispersibility/crystallinity of the VDD intermediate was observed. Increased Tg of the drying protectant was associated with improved redispersibility/crystallinity at a defined drum temperature. Consequently, the high Tg-substance trehalose and lactose showed a better performance than mannitol at higher drum temperatures. However, the processability and related powder properties were not in accordance with this observation. Mannitol containing formulations showed superior processibility to those containing trehalose/lactose. Moreover, the impact of the tableting and encapsulation process on the redispersibility of the VDD intermediate was studied for a selected formulation. Neither process demonstrated a negative impact on redispersibility. In conclusion, vacuum drum drying is a promising drying technique for the solidification of nanosuspensions to result in dried powder still containing ritonavir nanoparticles while demonstrating acceptable to good downstream processibility to tablets/capsules.Graphical

Study of the Load Forecasting of a Wet Mill Based on the CEEMDAN-Refined Composite Multiscale Dispersion Entropy and LSTM Nerve Net

To address the problem of wet ball milling in a strong noise environment, it is difficult to accurately detect the internal load parameters of the cylinder during grinding. In this paper, a mill load parameter prediction method is proposed based on complementary ensemble empirical mode decomposition (CEEMDAN)-refined composite multiscale dispersion entropy (RCMDE) and-long and short-term memory (LSTM) neural networks. Using this method, the vibration signals of the mill barrel under strong noise were decomposed using the CEEMDAN algorithm, sensitive modal components with strong correlation with the original signal were selected for reconstruction using the correlation coefficient method, and features of the reconstructed signals under different load parameters were extracted through RCMDE. The load characteristic vector of an RCMDE mill was used as the input of LSTM neural networks, and the filling rate, material and ball ratio, and grinding concentration were used as the output to establish the internal load prediction model of wet mill. Experiment results show that the prediction method has a high accuracy, with average absolute percentage errors of the filling rate, feed-to-ball ratio, and grinding concentration of 6.08%, 3.50%, and 3.47%, and average absolute errors were of 0.0167, 0.0146, and 0.0146, respectively.

Synthesis and Characterization of Cu2ZnSnSe4 by Non-Vacuum Method for Photovoltaic Applications.

Wet ball milling was used for the synthesis of Cu2ZnSnSe4 (CZTSe) nanoparticles with a kesterite structure. The prepared nanoparticles were used for ink formulation. Surfactants and binders were added to improve the ink stability, prevent agglomeration, and enhance ink adhesion. The films deposited via spin coating were annealed at different temperatures using a rapid thermal processing system in the presence of selenium powder in an inert environment. Analytical techniques, such as X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy, were used to confirm the formation of CZTSe nanoparticles with a single-phase, crystalline kesterite structure. Field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to study the surface morphology and chemical composition of the thin films before and after annealing, with and without the sodium solution. The optoelectrical properties were investigated using ultraviolet-visible spectroscopy and Hall measurements. All the prepared CZTSe thin films exhibited a p-type nature with an optical bandgap in the range of 0.82–1.02 eV. The open-circuit voltage and fill factor of the CZTSe-based devices increased from 266 to 335 mV and from 37.79% to 44.19%, respectively, indicating a decrease in the number of recombination centers after Na incorporation.

Influence of Homogenizing Methodology on Mechanical and Tribological Performance of Powder Metallurgy Processed Titanium Composites Reinforced by Graphene Nanoplatelets.

In the present work, 0.25 wt%GNP-Ti composites were prepared through powder metallurgy route by adopting three types of mixing modes to investigate the extent of mixing on the mechanical and tribological properties. Dry ball milling, wet ball milling, and rotator mixing were independently employed to homogenize the composite constituents. Three types of composite powders obtained were subsequently sintered into composite pellets by cold compaction followed by vacuum sintering. Morphological investigation of composite powders performed by SEM revealed better homogenization of GNPs in Ti matrix for dry ball milled composite powder, whereas wet ball milled and rotator mixed composite powders showed aggregation and bundling of GNPs. Micro Vickers hardness of composites produced via dry ball milling is 4.56% and 15.7% higher than wet ball milled and rotator mixed samples, respectively. Wear test performed by pin-on-disk tribometer showed higher wear loss for wet ball milled and rotator mixed composites in comparison to dry ball milled.

Accelerated degradation of sulfadiazine by wet mechanochemical synthesized nano-pyrite FeS2 based Fenton system: Performance, mechanism and applicability

Pyrite have been recognized as a promising Fenton reagent to degrade multitudinous organic contaminants. However, the dominating contribution of heterogeneous and homogeneous Fenton reaction to degradation in pyrite Fenton system is ambiguous. In this work, pyrite FeS2 nanoparticles were newly prepared by a wet ball milling method with iron, sulfur and ethanol without protective gas. A subsequent heat-treatment was used to optimize the pyrite crystallinity. The degradation performance of synthesized FeS2 Fenton system for sulfadiazine were systematically investigated for the first time. The synthesized FeS2 Fenton system exhibited ultra-fast and superior degradation ability at wide pH range (3–9) compared with current pyrite Fenton system and 100% sulfadiazine was removed in 4 min with 0.4 g/L FeS2, 2.5 mmol/L H2O2 and initial pH of 7. It’s found that ball milling process and heat-treatment affect the performance of synthesized FeS2 Fenton system. The pH self-adjustment induced by accelerated dissolution of amorphous FeS2 and the Fe2+/Fe3+ cyclic regeneration ability resulted in the dominating homogeneous Fenton reaction to degrade sulfadiazine. The maintained excellent degradation ability of synthesized FeS2 after reused three times, in scale-up system, exposed in air for 5 weeks or in real water system (tap water and river water) indicated its promising application possibility and the possible degradation pathways of sulfadiazine by synthesized FeS2 Fenton system were also proposed.

Ionic Conductivity versus Particle Size of Ball‐Milled Sulfide‐Based Solid Electrolytes: Strategy Towards Optimized Composite Cathode Performance in All‐Solid‐State Batteries

AbstractFor the fabrication of high‐energy and high‐power all‐solid‐state batteries (ASSBs), easily synthesizable solid electrolytes are needed, which enable fast ion transport inside the composite cathode as well as good contacts between cathode active material and solid electrolyte particles. Regarding the latter, the size ratio of the particles inside the composite cathode has to be optimized. Here, we use a wet ball milling process for the synthesis of agyrodite‐type Li5.5PS4.5Cl1.5 solid electrolyte particles and study the influence of milling time on particle size and ionic conductivity. With longer milling time, both the solid electrolyte particle size and the ionic conductivity decrease, which exert an opposing influence on the cathode performance. We show that a milling time of approximately 2 h leads to an optimum cathode performance, as this time is sufficient for a favorable particle size ratio, while a strong drop of the ionic conductivity of Li5.5PS4.5Cl1.5 is avoided.