High-energy Mechanical Ball Milling Research Articles

A Universal Self-Propagating Synthesis of Aluminum-Based Oxyhalide Solid-State Electrolytes.

Inorganic solid-state electrolytes (SSEs) play a vital role in high-energy all-solid-state batteries (ASSBs). However, the current method of SSE preparation usually involves high-energy mechanical ball milling and/or a high-temperature annealing process, which is not suitable for practical application. Here, a facile strategy is developed to realize the scalable synthesis of cost-effective aluminum-based oxyhalide SSEs, which involves a self-propagating method by the exothermic reaction of the raw materials. This strategy enables the synthesis of various aluminum-based oxyhalide SSEs with tunable components and high ionic conductivities (over 10-3 S cm-1 at 25 °C) for different cations (Li+, Na+, Ag+). It is elucidated that the amorphous matrix, which mainly consists of various oxidized chloroaluminate species that provide numerous sites for smooth ion migration, is actually the key factor for the achieved high conductivities. Benefit from their easy synthesis, low cost, and low weight, the aluminum-based oxyhalide SSEs synthesized by our approach could further promote practical application of high-energy-density ASSBs.

Construction of La2O3/AgCl S-scheme heterojunction with interfacial chemical bond for efficient photocatalytic degradation of bisphenol A

The formation of interfacial chemical bonds in S-scheme heterostructure is a crucial factor to realize efficient interfacial charge transfer. High-energy mechanical ball-milling is an effective method to form interfacial chemical bonds. In this work, an S-scheme La2O3/AgCl heterojunction catalyst was designed and prepared by ball-milling method. XPS, FTIR and Raman measurements showed that La-Cl chemical bond was formed at the interface of La2O3 and AgCl and an S-scheme charge transfer path mechanism existed in the La2O3/AgCl composite. The results of electrochemistry, photo-electrochemistry, capture experiments, free radical measurement and EPR verified that the S-scheme heterojunction and the interfacial La-Cl bond significantly accelerated the charge transfer rate between La2O3 and AgCl, and enhanced the photocatalytic capability of the composite catalysts. The degradation rate of bisphenol A by La2O3/AgCl heterojunction composite (LA50) reached 99 % in 20 min, and it also had excellent anti-interference ability and cycling stability. The toxicity of the degradation intermediates of bisphenol A was much less than itself, as calculated by TEST simulation. This work provided a promising strategy for improving the performance of S-scheme heterojunction catalysts by introducing interfacial chemical bonds as charge transfer channels.

Novel CuSi2P3-Based Semi-Solid Anolyte for Redox Flow Batteries

Introduction Redox flow batteries (RFBs), as a kind of low-cost, high-efficiency energy storage system, have received increasing attention in recent years. However, the energy density of RFBs is much lower than that of most commercialized lithium-ion batteries, which not only makes RFBs inconvenient in stationary energy storage but also greatly limits their application in many fieldsIn this work, a low-potential CuSi2P3-based composite is synthesized through a simple high-energy mechanical ball milling and impregnation method; then, it is used to prepare a semisolid anolyte, which is able to achieve a high volumetric capacity (320- 400 Ah L-1). The effect of adding binder to a composite is also discussed for the first time. The synthesis method of adding a binder to the composite provides a direction for optimizing the suspension for other active materials to be applied to semi-solid flow battery.Results and DiscussionFigure 1 compares the 1st and 10th galvanostatic discharge-charge cycling tests of two semisolid anolytes, 8 vol% CSP@C-10 vol% Super P (8CSP@C-10SP) and 8 vol% CSP@C-LiPAA-10 vol% Super P (8CSP@C-LiPAA-10SP). The specific capacity of 8CSP@CLiPAA-10SP anolyte at the first cycle can reach up to >2000 mAh g-1, which approaches the theoretical capacity (2079 mAh g-1) based on the corresponding binary Li-alloy products (Li3.75Si and Li3P), with the capacity retention greater than 98% from the 2nd to the 10th cycle. However, the specific capacity of 8CSP@C-10SP anolyte without LiPAA at the first cycle is only about 1000 mAh g-1, and severe capacity fading is encountered. Only a specific capacity of 420 mAh g-1 is left at the 10th cycle, leading to capacity retention of only 40%. The presence of LiPAA makes a more stable CSP composite, which can obtain a better cycling performance. We concluded that the cycling stability of LiPAA binder-based CSP composite is much better for RFBs compared with the one without binder.Figure 1b-e reveals the comparison of SEM images between 8CSP@C-10SP and 8CSP@C-LiPAA-10SP at pristine stage and after cycles respectively. It can be seen from the images that these two semisolid anolytes present very porous structure at the pristine stage (Figure 1b, d). However, after cycles, the surface of 8CSP@C-10SP produces very large film-like precipitates (Figure 1c), which greatly hinders the reaction of active materials in the subsequent cycles and further results in serious capacity fading. On the other hand, the porous structure of the 8CSP@C-LiPAA-10SP after cycles enables sound performance of the anolyte during the continuous cycles. The addition of LiPAA in the CSP composite can improve the contact between CSP and carbon, which confirms the electrical conductivity uniformity of CSP-based suspension.The addition of LiPAA binder to the composite enables the CSP semisolid anolytes to maintain better uniformity and rheological performance. Figure 2 shows the viscosity test results of electrolyte (1 M LiPF6 EC/DEC) and various CSP-based semisolid anolytes. It is indicated in the results that the non-Newtonian fluid semisolid anolytes present greater viscosity than the Newtonian fluid electrolytes, which results in larger flow resistance and more pump loss; therefore, viscosity is an important issue to be considered in the application of SSFBs. We find the viscosity of CSP@C-LiPAA anolyte significantly smaller than that of CSP@C anolyte at the same concentration, which is favorable to reduce the flow loss of the anolyte. The addition of LiPAA binder improves the rheological performance of the semisolid anolyte in an effective way and enormously enhances its cycling stability. Further investigations on the electrochemical reversibility, energy efficiency, cycle life, full cell design, and flow cell performance will be discussed. Acknowledgments The work described was substantially supported by a grant from the the Natural Science Foundation of Guangdong Province (2023A1515010954) and the Shenzhen Science and Technology Fund (JCYJ20220531101801002). Figure 1

The Analysis of the Application of Using Nanoceramic Oxides in Fire-resistant Coatings

The increased demand for enhanced fire safety in various industries has spurred interest in the properties and applications of nanoceramic oxide materials. This paper provides a thorough examination of the fundamental attributes of nanoceramic oxides, showcasing their exceptional temperature, corrosion, and wear resistance. The paper discusses synthesis methods like evaporation condensation, high-energy mechanical ball milling, and both vapor and liquid phase chemical techniques. The paper further explicates the underlying mechanisms that enable fire-resistant coatings to retard flames, highlighting thermal insulation, intumescence, and more. Of significance is the potential of nanoceramic oxides to augment the performance of these coatings, evidenced by applications like tunnel fire retardant coatings and steel structure coatings that integrate materials such as Mg (OH)2, nano-SiO2, and TiO2. While challenges in raw material sourcing, eco-friendliness, production, and expertise arise, solutions are proposed. Conclusively, the study underscores the transformative potential of nanoceramic oxides in the realm of fire-resistant coatings, pushing boundaries in fire safety across sectors.

Hydrolytic hydrogen production behavior in NaCl solution of Mg and Mg-GO composite synthesized by mechanochemical reaction

With the help of the mechanochemical reaction (MCR) strategy, the composition optimization, structure regulation and surface modification of metallic Mg are realized by introducing GO in the high energy mechanical ball milling process to enhance the hydrogen production performance in NaCl solution. The synthetic process of Mg and Mg-GO composite by MCR is systematically optimized and the microstructure evolution as well as the hydrolytic hydrogen production behavior are investigated. Phase composition optimization and microstructure regulation can be effectively implemented during the MCR process. The response rate of the repeated hydrogen-filling MCR sample is faster than that of the single hydrogen-filling MCR sample. The hydrogen production rates at 298 K of 4, 8, 12, 16 and 20 h MCR Mg with repeated H2-filling can reach to 922, 934, 890, 917 and 1131 mL/g/min, respectively. The internal microstructure refinement, surface modification, moderate activity, appropriate particle size, surface defects and reasonable mass transfer channels of MCR 8 h Mg-GO composite are the reasons for the fast rates and high yields of hydrolytic hydrogen production. 365.3, 864.4 and 933.8 mL/g H2 can be produced by 8 h MCR Mg-GO composite within 1, 3 and 10 min, respectively. The hydrogen production rate of 8 h MCR Mg-GO composite is as high as ∼600 mL/g/min. Mechanochemical reaction strategy with catalyst is a useful method to improve the hydrolysis hydrogen production performance of metallic Mg when well matched with the added catalyst.

Silicon infused Molybedenum di-selinide (MoSe2) nanosheets for enhanced hydrogen evolution reaction (HER) and lithium-ion battery (LIB) applications

The systematized design of two-dimensional (2D) nanocatalysts for sensible energy-efficient reactions is quite a puzzling prospective aspect in energy-related applications. In this current work, we used a top-down strategy to synthesize silicon (Si) nanoparticles using a high-energy mechanical ball milling technique. In hydrothermal reaction, these Si nanoparticles were introduced into the 2D MoSe2 matrix sequence based on varying the percentages of silicon (0–15%) vs Selinium content. The high crystalline phases of the synthesized 10% Si:MoSe2 exhibited the sheet-like morphology and silicon inserted layered structure. The pristine MoSe2@CC & Si:MoSe2@CC electrodes were prepared by tape casting method. During HER reaction, the miniscule insertion of Si into MoSe2 matrix amplified the current density until 10% addition and moved the reduction curves towards lower onset overpotential (76.23 mV) in addition to the significant Tafel value (112.3 mV/decade). The potential of the better performed electrode in HER was explored as an anode for Lithium-ion battery (LIB) applications. The electrode delivered a discharge capacity of 406.7 mAh g−1 at a current density of 100 mA/g after 100 charge-discharge cycles. Furthermore, the rationally constructed bifunctional electrode (Si:MoSe2@CC) showed strong physicochemical stability, which can be used in future sustainable energy generation and storage devices.

Enhanced photocatalytic performance of ZnO/AgCl composites prepared by high-energy mechanical ball milling

ZnO/AgCl composites prepared by high-energy ball milling showed excellent photocatalytic activity for RhB degradation and 1,4-DHP dehydrogenation under visible-light irradiation.

High-Capacity CuSi2P3-Based Semisolid Anolyte for Redox Flow Batteries.

Redox flow batteries (RFBs) have attracted more attention due to their ability of decoupling energy and power, but their low energy density has greatly restricted their applications. Semisolid flow batteries (SSFBs) are a kind of RFBs, but they have high energy density. However, there is a lack of research on semisolid anolytes, and thus the application of SSFBs is still in its infancy. In this work, a low-potential (0.6 V vs Li/Li+) CuSi2P3@C-LiPAA composite is synthesized through a simple high-energy mechanical ball milling and impregnation method based on the CuSi2P3 (CSP) compound; then, it is used to prepare a semisolid anolyte, which is able to achieve a high volumetric capacity of 400 Ah L-1 in static mode and 320 Ah L-1 in intermittent-flow mode. This is the highest volumetric capacity of anolyte so far. The effect of adding binder to a composite is also discussed for the first time, which makes the connection between the composite particles closer and the semisolid suspension more uniform so as to obtain stable electrochemical performance. At the same time, through pairing respectively with two types of catholytes, liquid 10-methylphenothiazine (MPT) and semisolid LiFePO4 (LFP), a single-cell voltage of 3 V and more than 100 stable cycles with the Coulombic efficiency of 99% have been achieved by CSP-MPT and CSP-LFP full-cell systems. The result fully demonstrates the applicability of the prepared CSP semisolid anolyte. The synthesis method of adding a binder to the composite in this work also provides a direction for optimizing the suspension for other active materials to be applied to SSFBs in the future.

Ni-Mo-Si]:Nb Bulk Metallic Glasses: Microstructure, Mechanical and Corrosion Studies

We examine the effect of substituting Niobium (Nb), on the glass-forming abilities (GFA), mechanical and corrosion properties of bulk metallic glasses (BMGs). BMGs are synthesized using the general formula of (Ni75Mo15Si10)100−xNbx (x = 0, 5, 10 and 15 at.%, labeled as NMSNb0, NMSNb5, NMSNb10 and NMSNb15) that are synthesized using high energy mechanical ball milling technique. Thermal, mechanical, and corrosion properties were enhanced significantly with an increase in Niobium (Nb) content of 10 at.% (NMSNb10). Using XRD analysis, the analysis related to phase attribution and crystallizability is scrutinized. Alloying this BMG with Molybdenum (Mo) and Niobium (Nb) helped avoid embrittlement in the sulphuric acid environment, overcoming strain cracking problems caused during welding, preventing pitting, crevice corrosion, and wet corrosion. Applicability of the present BMG system is examined in light of the correlation between morphology, mechanical, and corrosion studies.

Porous network carbon nanotubes/chitosan 3D printed composites based on ball milling for electromagnetic shielding

Carbon nanotubes (CNTs) are easy to agglomerate, which results in poor structure reproducibility, and seriously restricts the improvement of conductivity and electromagnetic interference (EMI) shielding properties of CNTs composites. In this study, CNTs were evenly dispersed in the chitosan (CS) matrix by a high energy mechanical ball milling method, and three-dimensional (3D) printing ink of CNTs/CS was obtained. The CNTs/CS composites with porous network structures are prepared by the 3D printing technology. The results show that the 3D porous network CNTs/CS composites can effectively absorb electromagnetic waves. The 3D printed CNTs/CS composites with porous networks show an exceptional EMI shielding effectiveness of 25.07 dB at a low density of 72 mg/cm3. According to the square hole grid structure of 3D printed products, the influence of pore size and conductivity of the composites on the EMI shielding performance is simulated and analyzed, which are consistent with the experimental results. For non-magnetic materials, conductivity has a greater influence on the EMI shielding performance than that of pore size. This study provides a new idea and method for the rapid and accurate preparation of polymer matrix composites with excellent EMI shielding properties as surface of electronic components.

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi).

CaCu3Ti4-x((A0.05Nb0.05))xO12 ceramics (A: Al and Bi; x = 0, 0.3) were synthesized by high-energy mechanical ball milling and reactive sintering at 1050 °C in air. Rietveld refinement of XRD data revealed the pure and (Al3+, Nb5+) cosubstituted ceramics contained a minor CuO secondary phase with a mole fraction of about 3.2% and 6.9%, respectively, along with a CaCu3Ti4O12 (CCTO)-like cubic structure. In addition, (Bi3+, Nb5+) cosubstituted ceramics had a pyrochlore (Ca2(Ti, Nb)2O7) secondary phase of about 18%. While the (Al3+, Nb5+) cosubstituted CCTO showed the highest relative permittivity (ε’ = 3.9 × 104), pure CCTO showed the lowest dielectric loss (tanδ = 0.023) at 1 kHz and 300 K. Impedance-spectroscopy (IS) measurements showed an electrically heterogeneous structure for the studied ceramics, where a semiconducting grain was surrounded by highly resistive grain boundary. The giant relative permittivity of the ceramics was attributed to the Maxwell–Wagner polarization effect at the blocking grain boundaries and domain boundaries. The higher tanδ of the cosubstituted samples was correlated with their lower grain boundary’s resistivity, as confirmed by IS analysis. Modulus-spectrum analysis revealed two relaxation processes for the pure and (Bi3+, Nb5+) cosubstituted CCTO samples. Dissimilar behavior was observed for the (Al3+, Nb5+) cosubstituted CCTO, where three relaxation mechanisms were observed and attributed to the grain, domain-boundary, and grain-boundary responses.

Friction and Wear Characterization of Spark Plasma Sintered Hybrid Aluminum Composite Under Different Sliding Conditions

Abstract Friction and wear behaviors of hybrid aluminum matrix self-lubricating nanocomposite, containing varying amount of nano-aluminum oxide (Al2O3) and graphene nanoplatelet (GNP) particles were investigated under dry and boundary lubrication sliding conditions. All the specimens were prepared by ultrasonic probe mixing followed by high-energy mechanical ball milling and spark plasma sintering fabrication route. The objective of this present study is to determine the tribological behavior of GNP as nanoreinforcement under dry and wet lubricating conditions. The wear test was carried out at room temperature on a ball-on-disc reciprocating tribometer with a contact load of 5 N, a frequency of 30 Hz, a stroke of 2 mm, and a sliding distance of 120 m. The chromium-plated chrome steel ball is used as the counter body for tribo-testing. From the results, it has been observed that GNP, as the solid lubricant reinforcement, reduces the friction by 25.33% and 68.14% under dry and wet lubricating conditions, respectively, for the hybrid composite. Reduction in wear volume by 91.15% and 90.50% is observed under dry and wet lubricating conditions, respectively, for the hybrid composite in comparison to the base eutectic Al–Si alloy. The reduction in the coefficient of friction and wear volume for the hybrid composite is attributed to the multilayer two-dimensional GNP nanoparticles that cause easy shearing by forming a conformal protective film layer on the sliding interface. Ultra-mild to severe wear regime was obtained for different composition samples including base composition to hybrid composition.

Structural and magnetic properties of Co/Al2O3 cermet synthesized by mechanical ball milling

Cobalt nanoparticles in the alumina matrix were synthesized using high energy mechanical ball milling of Co3O4 and Al powders mixture. The effect of ball mill time of 1 up to 12 h on the phase formation and crystalline lattice of the samples was investigated by the fitting of the X-ray diffraction patterns with Fullprof software and Rietveld method. The results show that 6 h milling of the primary powders yields a nanocomposite of Co/Al2O3 cermet. The formation of Co/Al2O3 nanocomposite was confirmed by a morphological study using scanning electron microscopy and transmission electron microscopy. The prepared nanocomposite by 12 h ball mill time has ferromagnetic properties with a high saturation magnetization value of 118 emu/g. Also, using Henkel plot analysis, it was shown that there are strong dipole-dipole magnetic interactions between the prepared cobalt nanoparticles in the Al2O3 matrix.

Preparation of exchange coupled CoFe2O4/CoFe2 nanopowders

The CoFe2O4 cobalt ferrite nanoparticles were synthesized by the hydrothermal method. At the reaction temperature of 200 °C, the particle sizes were controlled in the range of 22–41 nm by varying the reaction time tr from 2.0 to 15 h and the spontaneous magnetization Ms of samples was increased from 68.6 to 78.2 Am2/kg. The X-ray diffraction diagrams of obtained samples showed their pure ferrite spinel structure. The highest coercivity Hc value of 184.5 kA/m was achieved by tr = 8 h (denoted by CFO). The sample was synthesized with a time reaction of 2 h which was reduced to form CoFe2 (denoted by CF) nanoparticles by H2 flow 300 mL/min at 380 °C. The CFO/CF powders were milled by the high energy mechanical ball milling in a SPEX 8000. After milling for 2 h, the Ms and Hc values of the CFO/CF nanocomposite powders with 10 wt% CoFe2 nanoparticles fraction were 81.5 Am2/kg and 192.4 kA/m, respectively. The microstructure and magnetic properties of all samples are discussed in detail.

Recycling Chips of Stainless Steel Using a Full Factorial Design

The aim of this study was to provide an experimental investigation on the novel method for recycling chips of duplex stainless steel, with the addition of vanadium carbide, in order to produce metal/carbide composites from a high-energy mechanical milling process. Powders of duplex stainless steel with the addition of vanadium carbide were prepared by high-energy mechanical ball milling utilizing a planetary ball mill. For this proposal, experiments following a full factorial design with two replicates were planned, performed, and then analyzed. The four factors investigated in this study were rotation speed, milling time, powder to ball weight ratio and carbide percentage. For each factor, the experiments were conducted into two levels so that the internal behavior among them could be statistically estimated: 250 to 350 rpm for rotation speed, 10 to 50 h for milling time, 10:1 to 22:1 for powder to ball weight ratio, and 0 to 3% carbide percentage. In order to measure and characterize particle size, we utilized the analysis of particle size and a scanning electron microscopy. The results showed with the addition of carbide in the milling process cause an average of reduction in particle size when compared with the material without carbide added. All the four factors investigated in this study presented significant influence on the milling process of duplex stainless steel chips and the reduction of particle size. The statistical analysis showed that the addition of carbide in the process is the most influential factor, followed by the milling time, rotation speed and powder to ball weight ratio. Significant interaction effects among these factors were also identified.

Mechanical production and sonocatalytic application of Cu2S nanoparticles for degradation of isopropylxanthic acid: Kinetic modeling via white and black box methods

Three kinetic models were used for disclosing the kinetic characteristics of isopropylxanthic acid degradation via sonocatalytic process in the presence of Cu2S nanoparticles (NPs). The high-energy planetary mechanical ball milling (HEBM) was used for the production of Cu2S NPs in different milling times of 0.5, 1.5, 3 and 4.5 h. A thorough characterization analysis was performed to investigate some physical and chemical properties of the samples. The main oxidizing species during the sonocatalytic process were determined using organic and inorganic scavengers in different concentrations. In the first step, to calculate the sodium SIPX RE (%), a mathematical kinetic model, which is a type of deterministic white box model, was established based on the reaction mechanism, the scientific assumptions, and the responsible oxidizing species. Secondly, another category of deterministic white box modeling such as an empirical kinetic modeling was developed using nonlinear regression analysis based on the main key factors. The proposed kinetic models were able to closely describe the evolution of kapp with each of the operating parameters. Thirdly, a three layered feed forward back propagation neural network (ANN), as a type of black box modeling, was built to compare the effectiveness of the two groups of the models. Prediction results by ANN declared the high accuracy of this model (R2 and MSE values were 0.995 and 4.361, respectively). Finally, analysis of variance (ANOVA) used to compare the ability and the accuracy of the three developed models. ANOVA results showed that there was a significant difference between the predicted values of the deterministic white box models and the black box model. Therefore, under certain operating conditions, the models could not be used instead.

Thermal-alteration interphase transformations in natural and synthetic arsenic sulfide polymorphs

Abstract Thermal-alteration interphase transformations in natural (realgar α-As4S4 of two mineral origins) and synthetic (commercial powdered high-temperature β-As4S4 modification synthesized from elemental constituents and subjected to high-energy mechanical ball milling) arsenic monosulfide polymorphs are studied exploring temperature-modulated DSC TOPEM® method. Specific heat capacity and non-reversing heat flow variations in realgar α-As4S4 demonstrate two endothermic events, these being ascribed to interphase α → β transformation at ∼(540–550) K, and melting of this newly-formed high-temperature β-As4S4 phase at 581–582 K. This polymorph originated from thermal alteration of mineral realgar possesses congruent melting in contrast to synthetic β-As4S4 polymorph, which shows non-equilibrium melting due to accompanied generation of compositionally-authentic amorphous phase. Calorimetric studies on synthetic β-As4S4 in powdered coarse-grained and milled states demonstrate complicated non-equilibrium melting in principally different crystalline-amorphous environments along with crystal-to-glass transformation. Structural-chemical heterogeneity of β-As4S4 crystallites results in incongruent double-peak melting through two endothermic events at ∼578 K and ∼588 K. The amorphous phase formed under high-energy milling of synthetic β-As4S4 possesses a dual nature due to stabilization of As-rich glassy substances with low- and high-temperature glass transition mid-points. This process in the powdered synthetic β-As4S4, identified as re-amorphization of initial amorphous phase and direct vitrification from β-As4S4 crystallites, was parameterized as compared to calorimetric thermal-alteration events in orpiment As2S3 mineral.

(Invited) From Lithium-Ion to Sodium-Ion Capacitors Using the Strategy of Sacrificial Cathodic Materials

Nowadays, improving the energy output of electrochemical capacitors (ECs) is still a challenge for researchers. In this context, the lithium-ion capacitors (LICs) which exhibit higher energy density than EDLCs, at comparable power, are considered to be very promising energy storage devices. However, the necessary pre-lithiation of the negative graphite electrode constitutes a drawback of these systems. In the first concept of LIC, metallic lithium was used as auxiliary electrode for graphite pre-lithiation [1]. Since this additional electrode complicates the cell construction and may cause safety issues, it has then been proposed to implement a concentrated electrolyte solution as source of lithium ions, yet it resulted in noticeable decrease of electrolyte concentration and ionic conductivity [2]. Therefore, another strategy was to incorporate lithium metal oxide (from which lithium ions can be irreversibly extracted) in the positive activated carbon (AC) electrode. Once the graphite intercalation compound is formed, the LIC can be cycled, while the de-lithiated oxide in the positive electrode is electrochemically inactive [3,4]. Notwithstanding, the use of oxides such as Li5ReO6 [3] or Li5FeO4 [4] requires a relatively high oxidation potential (up to 4.3 - 4.7 V vs. Li/Li+) which may cause parasitic oxidation of the electrolyte. Recently, we have demonstrated that these drawbacks can be solved by using a renewable salt, namely 3,4-dihydroxybenzonitrile dilithium salt (Li2DHBN), in combination with activated carbon [5]. Lithium is irreversibly extracted from Li2DHBN ca. 3.2 V vs. Li+/Li, and the residual organic material later dissolves in the electrolyte, while the cell continues to operate as a LIC. Despite the aforementioned advantages of pre-lithiation through a sacrificial cathodic material to prepare LICs, the possibility of lithium plating when high currents are employed and the low natural abundance of lithium remain some disadvantages of these systems. Therefore, our scientific attention was lately attracted by Na-ion capacitors (NICs), owing to few potential advantages as low cost of sodium, the possibility of using low-priced current collectors made of aluminum for the negative electrode. Our present work is focused on developing a NIC where Na2S is employed as sacrificial material for sodium insertion into a Sn-P intermetallic negative electrode. The Sn-P intermetallic was formed by facile high-energy mechanical ball milling in Ar atmosphere. Afterwards, Sn-P was mixed with hard carbon (HC) in the mass ratio 3:7 by ball-milling. A negative electrode coated on copper foil was obtained by mixing HC/Sn-P together with carbon black and CMC binder. A Na2S/AC positive electrode was prepared by mixing Na2S with activated carbon (AC), carbon black and PTFE binder. A huge irreversible capacity of 676 mAhg-1 (theoretical capacity of 687 mAhg-1) was observed below 3.8 V vs. Na+/Na during galvanostatic oxidation/reduction of Na2S/AC in a cell where metallic sodium was used as counter and reference electrode. A NIC cell was assembled with Na2S/AC positive electrode, Sn-P/HC negative electrode and a Na metal pin reference electrode. The electrolyte was 1 mol L-1 NaClO4 in a mixture of ethylene carbonate (EC) and propylene carbonate (PC) with 1:1 volume ratio. Once pre-sodiation was completed, AC became the active material for electrical double-layer charging, while reversible sodium insertion/deinsertion occurs at the Sn-P/HC electrode. The NIC system demonstrated excellent capacitance stability in the cell potential range 2.2 V - 3.8 V and a high energy density of 49 Wh kg-1 at 500 mAg-1. The obtained results confirm that the combination of HC/Sn-P intermetallic negative electrode with Na2S sacrificial material is a promising solution for a new generation of NICs. Acknowledgements The authors acknowledge the Foundation for Polish Science for funding the HYCAP project (research grant TEAM TECH/2016-3/17).

Micro-structural, dielectric, ferroelectric and piezoelectric properties of mechanically processed (Pb1−xLax)(Zr0.60Ti0.40)O3 ceramics

In this work, (Pb1−xLax)(Zr0.60Ti0.40)O3 (PLZT x/60/40, x = at.%) ceramics were prepared by using high energy mechanical ball milling followed by cold isostatic pressing (CIP), investigated for their micro-structural, dielectirc, ferroelectric and piezoelectric properties. Mechanical activation results in the highly reactive nature of the nano size milled PLZT powders, which enables the partial perovskite phase formation, confirmed by room temperature XRD patterns. CIP leads to a higher density with a closely packed dense microstructure of sintered PLZT ceramics shown in SEM images. The grain size of PLZT x/60/40 ceramics was found to be decreasing with increasing La3+ content. The highest relative density of ~ 97% was found to be for PLZT 8/60/40 ceramics with grain size of ~ 1.35 µm. The PLZT 8/60/40 system also shows the highest dielectric constant of ~ 1976, remnant polarization of 29.1 µC/cm2, piezoelectric coefficients (d33 $$~ \cong ~$$ 570 pC/N, g33 $$~ \cong ~$$ 28.03 × 10−3 Vm/N) and electromechanical coupling factors (kp = k33 = 64.1% and k31 = 54%). The elastic compliances for the PLZT x/60/40 ceramics were also obtained.

GeP3 with soft and tunable bonding nature enabling highly reversible alloying with Na ions

A GeP3 compound is introduced here for the first time as a promising anode for sodium-ion batteries (SIBs). The compound shows a high capacity and good cyclic stability, which well agree with the first-principle calculation results regarding its soft bonding nature and related innovative mechanical endurance. The binding energies of Ge–P and P–P verify that Ge–P has softer bonding feature with smaller energy variations compared to P–P when the bonding length is changed. In order to confirm the bonding natures and their effect on the mechanical and electrochemical properties, two layered GePn compounds with different Ge–P content (i.e., GeP3 and GeP5) have been synthesized using a high energy mechanical ball-milling (HEMM) method. GeP3 maintains high discharge and charge capacities of 1.274 and 1.269 Ah g−1 even after 150 cycles, respectively, which correspond to capacity retentions of 87.6% and 88.0% from the 5th cycle, respectively. A comparative study on the elastic moduli of GeP3 and GeP5 demonstrates how the superior electrochemical performance of GeP3 is correlated with its more softened bonding feature compared to GeP5 both in the pristine state and during charge/discharge. The elastic modulus of GeP3 shows significantly softer features than that of GeP5, implying that mechanical stress or strain can be more easily alleviated in GeP3 than in GeP5 during charge/discharge. A morphological comparison between GeP3 and GeP5 electrodes reveals that GeP5 electrode undergoes very serious morphology and volume changes, whereas GeP3 electrode does not show any significant change in good accordance with the elastic modulus comparison from the first-principle calculations.