Sodium ion batteries(SIBs)are an exciting alternative for post-lithium energy storage.They can be regarded as a promising and cost-efficient solution for grid applications as they exhibit similar’rocking chair’mecha...Sodium ion batteries(SIBs)are an exciting alternative for post-lithium energy storage.They can be regarded as a promising and cost-efficient solution for grid applications as they exhibit similar’rocking chair’mechanism as lithium ion batteries,in addition to the abundance and low cost of sodium resources.Indeed,electrode materials,electrolytes,separators and smart design strategies are under spot and researchers are competing to come up with the ideal battery.Layered oxides with mixed structures are regarded as new concept that can offer a set of desired structural and energetic properties and are an attractive choice for next generation sodium ion batteries.However,unlocking this system chemistry,kinetics and reliable understanding of the intercalation/deintercalation mechanism upon electrochemical cycling is quite challenging.This review,through the examination of literature,gives a brief summary of the research progress and recent advances in the investigation of electrode materials based on layered oxides with mixed structures for sodium ion batteries.This new strategy leads in fact to positive electrodes with enhanced energetic performance as they consist of a combination of the energetic or/and structural properties of the existing structures.展开更多
The structure evolution and electrochemical performance of Na SICON-type Ca_(0.5)Ti_(2)(PO_(4))_(3) for sodium batteries are presented.This phosphate was synthesized by a solid-state method,and the obtained particles ...The structure evolution and electrochemical performance of Na SICON-type Ca_(0.5)Ti_(2)(PO_(4))_(3) for sodium batteries are presented.This phosphate was synthesized by a solid-state method,and the obtained particles were coated with carbon using sucrose.This compound crystallizes in the rhombohedral system with space group R-3.The presence of carbon in the Ca_(0.5)Ti_(2)(PO_(4))_(3)/C composite was confirmed by Raman and Thermogravimetric analysis.The electrochemical performance of Ca_(0.5)Ti_(2)(PO_(4))_(3)/C was investigated in the potential window 1.5–3.0 V vs.sodium metal at different scan rates.The compound is able to initially intercalate/deintercalate 1.6/1.15 Na per formula unit,respectively.In operando synchrotron diffraction was done in the potential window 0.02–3.0 V vs.Na|Na+and revealed the occurrence of several reaction regions upon first discharge.Up to 4 Na+ion per formula unit can be inserted during the first discharge.An intensive refinement of the synchrotron X-ray diffraction(SXRD)patterns of discharged Ca_(0.5)Ti_(2)(PO_(4))_(3) evidenced the existence of five regions depending on the sodium content while the crystal structures of new phases were elucidated for the first time where sodium insertion occurs in the unusual M3 and M’3 sites of the Na SICON structure.展开更多
Electronic and dielectric properties are essential for understanding many functional materials,predicting their behavior and optimizing their performance across different shapes,geometries and scales.Several approache...Electronic and dielectric properties are essential for understanding many functional materials,predicting their behavior and optimizing their performance across different shapes,geometries and scales.Several approaches were developed and explored to investigate more or less deeply the appropriate properties.One of the most appealing,accurate and efficient approach is first principle simulations based on modern theory of polarization.Especially with the increased availability of powerful computational resources and techniques.Building upon these advancements,our contribution aims to elucidate an efficient methodology for studying electronic and dielectric properties by applying the Berry phase and Maximally Localized Wannier functions methods.Our exploration will initially focus on a systematic study of the electronic,chemical bonding,ferroelectric and piezoelectric properties of the well-known prototypical bulk system PbTiO_(3).Subsequently,we will extend our study to examine slab properties as surface termination and slab thickness effect on electronic properties,utilizing the robust Wannier-justified Tight Binding model.展开更多
Ba0.85Ca0.15Zr0.10Ti0.90O3(BCZT)lead-free ceramics demonstrated excellent dielectric,ferroelectric,and piezoelectric properties at the morphotropic phase boundary(MPB).So far,to study the effect of morphological chang...Ba0.85Ca0.15Zr0.10Ti0.90O3(BCZT)lead-free ceramics demonstrated excellent dielectric,ferroelectric,and piezoelectric properties at the morphotropic phase boundary(MPB).So far,to study the effect of morphological changes on dielectric and ferroelectric properties in lead-free BCZT ceramics,researchers have mostly focused on the influence of spherical grain shape change.In this study,BCZT ceramics with rod-like grains and aspect ratio of about 10 were synthesized by surfactant-assisted solvothermal route.X-ray diffraction(XRD)and selected area electron diffraction(SAED)performed at room temperature confirm the crystallization of pure perovskite with tetragonal symmetry.Scanning electron microscopy(SEM)image showed that BCZT ceramics have kept the 1D rod-like grains with an average aspect ratio of about 4.Rod-like BCZT ceramics exhibit enhanced dielectric ferroelectric(εr=11,906,tanδ=0.014,Pr=6.01μC/cm^2,and Ec=2.46 kV/cm),and electrocaloric properties(ΔT=0.492 K andz=0.289(K×mm)/kV at 17 kV/cm)with respect to spherical BCZT ceramics.Therefore,rod-like BCZT lead-free ceramics have good potential to be used in solid-state refrigeration technology.展开更多
The eco-responsible lead-free piezoelectric ceramics have been intensively searched for more than adecade, however, the final goal to replace toxic ceramics like lead zirconate titanate (PZT) with lead-freecompounds, ...The eco-responsible lead-free piezoelectric ceramics have been intensively searched for more than adecade, however, the final goal to replace toxic ceramics like lead zirconate titanate (PZT) with lead-freecompounds, having comparable or even better performance has not yet been reached. In this road, thelead-free ceramics Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3) (BCZT), possessing excellent dielectric, ferroelectric, andpiezoelectric properties are regarded as serious candidates for the PZT replacement. Besides, nano-structuring BCZT is of paramount importance to enhance these functionalities even more. Here, BCZTmultipodes are designed by template-growth hydrothermal synthesis using hydrogen zirconate titanatenanowires. We demonstrate that the fabricated BCZT multipodes exhibit high dielectric permittivity of5300 with a temperature stability coefficient of ±5.9% between 20 and 140℃. A significant recoveredenergy density of 315.0 mJ/cm^(3) with high thermal stability and high energy storage efficiency of 87.4%,and enhanced large-signal piezoelectric coefficient d^(*)_(33) (310 pm/V) are found. Compared to the tradi-tional BCZT ceramics reported in the literature, relying on high-temperature processing, our sampleexhibits boosted energy storage parameters at a much lower temperature. These outcomes may offer anew strategy to tailor eco-responsible relaxor ferroelectrics toward superior energy storage performancefor ceramic capacitor applications.展开更多
基金Mohammed Ⅵ Polytechnic University for the financial support。
文摘Sodium ion batteries(SIBs)are an exciting alternative for post-lithium energy storage.They can be regarded as a promising and cost-efficient solution for grid applications as they exhibit similar’rocking chair’mechanism as lithium ion batteries,in addition to the abundance and low cost of sodium resources.Indeed,electrode materials,electrolytes,separators and smart design strategies are under spot and researchers are competing to come up with the ideal battery.Layered oxides with mixed structures are regarded as new concept that can offer a set of desired structural and energetic properties and are an attractive choice for next generation sodium ion batteries.However,unlocking this system chemistry,kinetics and reliable understanding of the intercalation/deintercalation mechanism upon electrochemical cycling is quite challenging.This review,through the examination of literature,gives a brief summary of the research progress and recent advances in the investigation of electrode materials based on layered oxides with mixed structures for sodium ion batteries.This new strategy leads in fact to positive electrodes with enhanced energetic performance as they consist of a combination of the energetic or/and structural properties of the existing structures.
基金the project e-STORE(APRD Program)funded by OCP Foundationwas partially funded by the German Research Foundation(DFG)under Project ID 390874152(POLi S Cluster of Excellence)。
文摘The structure evolution and electrochemical performance of Na SICON-type Ca_(0.5)Ti_(2)(PO_(4))_(3) for sodium batteries are presented.This phosphate was synthesized by a solid-state method,and the obtained particles were coated with carbon using sucrose.This compound crystallizes in the rhombohedral system with space group R-3.The presence of carbon in the Ca_(0.5)Ti_(2)(PO_(4))_(3)/C composite was confirmed by Raman and Thermogravimetric analysis.The electrochemical performance of Ca_(0.5)Ti_(2)(PO_(4))_(3)/C was investigated in the potential window 1.5–3.0 V vs.sodium metal at different scan rates.The compound is able to initially intercalate/deintercalate 1.6/1.15 Na per formula unit,respectively.In operando synchrotron diffraction was done in the potential window 0.02–3.0 V vs.Na|Na+and revealed the occurrence of several reaction regions upon first discharge.Up to 4 Na+ion per formula unit can be inserted during the first discharge.An intensive refinement of the synchrotron X-ray diffraction(SXRD)patterns of discharged Ca_(0.5)Ti_(2)(PO_(4))_(3) evidenced the existence of five regions depending on the sodium content while the crystal structures of new phases were elucidated for the first time where sodium insertion occurs in the unusual M3 and M’3 sites of the Na SICON structure.
基金supported by computational resources from HPC-MARWAN(hpc.marwan.ma)provided by the National Center for Scientific and Technical Research(CNRST),Rabat,Morocco.
文摘Electronic and dielectric properties are essential for understanding many functional materials,predicting their behavior and optimizing their performance across different shapes,geometries and scales.Several approaches were developed and explored to investigate more or less deeply the appropriate properties.One of the most appealing,accurate and efficient approach is first principle simulations based on modern theory of polarization.Especially with the increased availability of powerful computational resources and techniques.Building upon these advancements,our contribution aims to elucidate an efficient methodology for studying electronic and dielectric properties by applying the Berry phase and Maximally Localized Wannier functions methods.Our exploration will initially focus on a systematic study of the electronic,chemical bonding,ferroelectric and piezoelectric properties of the well-known prototypical bulk system PbTiO_(3).Subsequently,we will extend our study to examine slab properties as surface termination and slab thickness effect on electronic properties,utilizing the robust Wannier-justified Tight Binding model.
基金The authors gratefully acknowledge the generous financial support of CNRST Priority Program(PPR 15/2015)Slovenian Research Agency Program(P1-0125)European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie Grant Agreement(No.778072).
文摘Ba0.85Ca0.15Zr0.10Ti0.90O3(BCZT)lead-free ceramics demonstrated excellent dielectric,ferroelectric,and piezoelectric properties at the morphotropic phase boundary(MPB).So far,to study the effect of morphological changes on dielectric and ferroelectric properties in lead-free BCZT ceramics,researchers have mostly focused on the influence of spherical grain shape change.In this study,BCZT ceramics with rod-like grains and aspect ratio of about 10 were synthesized by surfactant-assisted solvothermal route.X-ray diffraction(XRD)and selected area electron diffraction(SAED)performed at room temperature confirm the crystallization of pure perovskite with tetragonal symmetry.Scanning electron microscopy(SEM)image showed that BCZT ceramics have kept the 1D rod-like grains with an average aspect ratio of about 4.Rod-like BCZT ceramics exhibit enhanced dielectric ferroelectric(εr=11,906,tanδ=0.014,Pr=6.01μC/cm^2,and Ec=2.46 kV/cm),and electrocaloric properties(ΔT=0.492 K andz=0.289(K×mm)/kV at 17 kV/cm)with respect to spherical BCZT ceramics.Therefore,rod-like BCZT lead-free ceramics have good potential to be used in solid-state refrigeration technology.
基金The authors gratefully acknowledge the generous financial support of the European Union Horizon 2020 Research and Inno-vation actions MSCA-RISE-ENGIMA(No.778072)MSCA-RISE-MELON(No.872631)Z.K.,B.R.,D.V.,and M.S.acknowledge the Slovenian Research Agency program P1-0125 and P2-0091.
文摘The eco-responsible lead-free piezoelectric ceramics have been intensively searched for more than adecade, however, the final goal to replace toxic ceramics like lead zirconate titanate (PZT) with lead-freecompounds, having comparable or even better performance has not yet been reached. In this road, thelead-free ceramics Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3) (BCZT), possessing excellent dielectric, ferroelectric, andpiezoelectric properties are regarded as serious candidates for the PZT replacement. Besides, nano-structuring BCZT is of paramount importance to enhance these functionalities even more. Here, BCZTmultipodes are designed by template-growth hydrothermal synthesis using hydrogen zirconate titanatenanowires. We demonstrate that the fabricated BCZT multipodes exhibit high dielectric permittivity of5300 with a temperature stability coefficient of ±5.9% between 20 and 140℃. A significant recoveredenergy density of 315.0 mJ/cm^(3) with high thermal stability and high energy storage efficiency of 87.4%,and enhanced large-signal piezoelectric coefficient d^(*)_(33) (310 pm/V) are found. Compared to the tradi-tional BCZT ceramics reported in the literature, relying on high-temperature processing, our sampleexhibits boosted energy storage parameters at a much lower temperature. These outcomes may offer anew strategy to tailor eco-responsible relaxor ferroelectrics toward superior energy storage performancefor ceramic capacitor applications.
