Polarization Relaxation Research Articles

Construction of NiCeOx nanosheets-skeleton cross-linked by carbon nanotubes networks for efficient electromagnetic wave absorption

In this work, two-dimensional NiCeOx nanosheet-modified carbon nanotubes (CNTs) composites were prepared by a hydrothermal method. NiCeOx with different morphologies can be formed by adjusting the addition ratio of nickel salt and cerium salt, and the introduction of CNTs in the subsequent synthesis process can effectively prevent the aggregation of NiCeOx nanosheets. Microstructural studies show that hexagonal NiCeOx nanosheets with a size of 100 nm are uniformly intertwined with CNTs. When applied to the attenuation of electromagnetic waves, NiCeOx/CNTs composites exhibit better electromagnetic wave (EMW) absorption performance than pure CNTs and NiCeOx nanosheets due to improved impedance matching and multiple polarization relaxation. At the matching thickness of 1.9 mm, the composite exhibits a minimum reflection loss (RLmin) of –53.2 dB and an effective absorption bandwidth (RL < –10 dB) of 5.04 GHz with a thickness of 2.3 mm. These results indicate that the as-prepared NiCeOx/CNTs composites have excellent EMW absorption performance and are expected to be a candidate material for EMW absorption.

Three-dimensional polyaniline/cerium oxide composite aerogel with enhanced microwave absorption properties

In order to develop microwave absorbing materials with strong absorption capacity, wide bandwidth and light weight, three-dimensional (3D) PANI/CeO2 composite aerogel was prepared by in-situ synthesis method in this work. The CeO2 nanorods are observed to be interlinked with PANI aerogel to form a porous nanofiber structure. The PANI/CeO2 composite aerogel exhibits excellent absorption performance with an absorption peak of − 53.68 dB under a moderate thickness of 2.5 mm, and the effective absorption bandwidth (EAB) achieves 4.44 GHz. The excellent microwave absorption performance of PANI/CeO2 composite aerogel was ascribed to the interfacial polarization relaxation and space charge polarization by virtue of the 3D conductive network. Furthermore, the oxygen vacancy defects arising from the CeO2 nanostructure also contribute greatly to the microwave absorption.

Hollow Spheres of Ti3C2Tx with a Nanometer-Thick Wall for High-Performance Microwave Absorption

Two-dimensional (2D) Ti3C2Tx MXene has attracted huge attention in the field of electromagnetic wave attenuation, but its poor impedance matching with air leads to weak microwave absorption (MA) capability. Herein, hollow spheres of Ti3C2Tx with a nanometer-thick wall were prepared through a sacrificial template strategy, and their MA performance was investigated for the first time. The unique macroporous structure constructed by Ti3C2Tx hollow spheres benefits excellent MA performance by improving impedance matching, multiple reflections and scattering, and polarization relaxation. With only 10 wt % filler loading in the paraffin, the minimum reflection loss (RLmin) of Ti3C2Tx hollow spheres can reach −49.2 dB at 10.3 GHz at a thickness of 2 mm, which is much superior to that of Ti3C2Tx nanosheets (−7.4 dB). Moreover, the MA performance of Ti3C2Tx hollow spheres can be adjusted in the range of 3.7–16.5 GHz by changing the cavity size and thickness. This study provides a facile and effective strategy for designing lightweight and high-performance MXene-based microwave absorbers.

Synthesis of effective microwave absorber C/ZnS/Cu composites via molten salt route

A novel multi-component composites C/ZnS/Cu is synthesized via molten salt method (MSM) for the microwave absorbing (MA) materials. The Cu acts as conductive centers to build a conductive system with carbon and the heterostructures among the ZnS, Cu and C promote the polarization relaxation effect. The result indicates that the value of reflection loss (RL) of C/ZnS/Cu can reach – 63.64 dB and the effective absorption band (EAB) reach 6.48 GHz, which is superior to the MA properties of many current reports. The contrast tests explore the effect of holding times on the MA performance of C/ZnS/Cu composites. This research expands the application of MSM in the MA field, and provides a reference for the MSM preparation of MA materials.

Green-in-green biohybrids as transient biotriboelectric nanogenerators

Green self-powered devices based on biodegradable materials have attracted widespread attention. Here, we propose the construction of the transient biotriboelectric nanogenerator (TENG) using green-in-green bionanocompoites. The green-in-green nanocomposites, cellulose nanocrystal (CNC)/polyhydroxybutyrate (PHB), are prepared with a high-pressure molding method. The CNC promotes the degradation and enhances the dielectric constant of CNC/PHB. It further allows for the significant improvement of the triboelectric output of CNC/PHB-based TENG. The voltage output and current output of CNC/PHB-based TENG are 5.7 and 12.5 times higher than those of pristine PHB-based TENG, respectively. Also, the bio-TENG exhibits admirable signal stability in over 20000 cycles. Despite the high hardness of CNC/PHB, a soft but simple-structured arch sensor is successfully assembled using CNC/PHB-based TENG. It can attain the precise real-time monitoring of various human motions. This study may provide new insights into the design/fabrication of green functional materials, and initiate the next wave of innovations in eco-friendly self-powered devices.

Heterostructure design of MOFs derived Co9S8/FeCoS2/C composite with efficient microwave absorption and waterproof functions

• A hierarchical Co9S8/FeCoS2/C composite has been designed. • Benefiting from the enhanced polarization loss, optimized synergistic effect, and multiscale EMW dissipation paths, Co9S8/FeCoS2/C composite exhibits superior EMW absorption. • The bouquet-like architecture formed by many nanorods produces a large number of void spaces and interfaces. • The obtained Co9S8/FeCoS2/C composite shows a broad effective bandwidth of 5.1 GHz at a thickness of 2 mm. At present, the problem of electromagnetic wave (EMW) pollution is critical, and the design of high-performance absorbers is of great significance. Based on the synergy between dielectric and magnetic losses, and between multicomponents in heterostructures, the development of light-weight absorbers with a strong absorption capability and multiple scattering is a promising strategy to achieve high-performance absorbers. In this work, CoFe-MOF precursors with a bouquet-like structure were prepared via the hydrothermal method, and Co 7 Fe 3 /C and Co 9 S 8 / FeCoS 2 /C composites were obtained through a carbonization and sulfuration treatment during the high-temperature pyrolysis process, respectively. The experimental and theoretical results show that the Co 9 S 8 /FeCoS 2 /C composite has a better EMW absorption performance, and its optimal reflection loss (RL) value is -53.9 dB at a low filler loading of 20 wt.%, which is due to the S doping that enhances the interface polarization relaxation process and improves the impedance matching characteristics. Moreover, the Co 9 S 8 /FeCoS 2 /C composite can be as candidates of high-efficiency absorbers in extreme application environments.

Asymmetric multilayered MXene-AgNWs/cellulose nanofiber composite films with antibacterial properties for high-efficiency electromagnetic interference shielding

• Multilayer films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. • The effects of different conductive layers order and different number of layers on electromagnetic shielding performance were investigated. • Due to the excellent layered structure, the MXene-AgNWs/cellulose nanofiber composite film exhibits excellent EMI shielding capability at an ultra-thin thickness. • Benefiting from the properties of silver nanowires, the multifunctional shielding composite exhibits excellent antibacterial properties and better environmental adaptability. Flexible, lightweight, robust and versatile properties are essential for the next generation of wearable as well as intelligent electromagnetic interference (EMI) shielding materials. In this work, multilayered films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. Compared with a uniformly mixed film, the resultant layered composite films that loaded with a low MXene and AgNWs content exhibit superior mechanical properties with a tensile strength of 137 MPa, a strain at break of 5.7%, excellent EMI shielding effectiveness (EMI SE) of 61.9 dB, and higher EMI SE/t of 20,653 dB cm −1 . This is attributed to the high-performance CNF substrate, the highly efficient layered structures, and extensive hydrogen-bonding interactions. In particular, a high degree of ohmic loss of multiple interfaces and polarization relaxation of local defects, as well as an abundance of terminal groups, favor the loss of electromagnetic waves (EMW) within the material. In addition, the prepared multifunctional layered composite films also show good antibacterial properties. As a result, the obtained new kind of flexible layered structure EMI shielding composite films with excellent EMI shielding performance, and mechanical properties present promising application prospects in the fields of EMI shielding and protection for aerospace, portable, and wearable flexible electronic devices.

Construction of urchin-like multiple core-shelled Co/CoS2@NC@MoS2 composites for effective microwave absorption

Designing nanocomposite with multi-level interfaces is an effective approach to improving the microwave absorbing capability of materials. In this study, the urchin-like multiple core-shelled Co/CoS2@NC@MoS2 composites (CCM) are designed and fabricated by high-temperature pyrolysis and solvothermal process, where the structure and phase composition are affected by the migration of Co. Abundant interfaces in the multiple core-shelled structures favor the polarization relaxation loss, defects of MoS2 and nitrogen doping carbon (NC) matrix induce the dipole orientation polarization loss. The CCM composite exhibits excellent microwave absorption with the strongest reflection loss (RL) of − 43.9 dB. Meanwhile, the broadest effective absorption bandwidth (EAB, RL<−10 dB) is 4.4 GHz with a thickness of 1.5 mm. Besides, with the thickness of 1.0–3.5 mm, all peaks of RLmin< −20 dB (99 % absorptivity). It is believed that this work can provide an effective strategy for the design of tunable multi-interface nanostructures to regulate microwave absorption.

Effect of B4C content and annealing on complex permittivity and microwave-absorption properties of B4C/Al2O3 coatings

The B4C/Al2O3 coatings were fabricated by air plasma spraying technology, and their complex permittivity and microwave absorption properties in the X-band were investigated before and after annealing (500 °C/2 h). Both the real and imaginary parts of the complex permittivity of the coatings decreased after annealing, which can be attributed to the weakening of polarization relaxation intensity and the reduction of electrical conductivity caused by the escape of carbon atoms. In addition, the density of B4C/Al2O3 coatings decreased from 3.01 to 2.16 g/cm3 with increasing B4C content. The B4C/Al2O3 coatings exhibit a minimum reflection loss (RL) value of −39.58 dB and the effective absorption bandwidth (RL＜−10 dB, EAB) covers 1.9 GHz at a thickness of 1.6 mm. After annealing, the above coatings still had an EAB of 1 GHz. Therefore, the B4C/Al2O3 coatings can be considered as a promising microwave-absorption candidate with good high-temperature microwave-absorbing performance and low density.

Preparation of a novel cross‐linked polyetherimide with enhanced breakdown strength and high‐temperature energy storage performance

AbstractPolymer dielectrics with excellent energy storage performance at high temperature are urgently needed in advanced applications, such as hybrid electric vehicles, smart grid and pulsed power sources. Polyetherimide (PEI), which is supposed to be the most promising candidate among polymer dielectric materials, displays a limitation for high‐temperature polymer dielectrics owing to the rapidly decreasing discharged energy density (Ud) and charge‐discharge efficiency (η). Herein, a novel PEI with cross‐linked networks was firstly prepared by utilising 2,4,6‐Triaminopyrimidine (TAP) as a cross‐linker. The results showed that the breakdown strength of the cross‐linked PEI (c‐PEI) with 2 wt% TAP increased to 399.4 MV/m, showing an increment of 23.3% in comparison with non‐cross‐linked PEI. Additionally, owing to the restrained polarisation loss and relaxation loss by cross‐linked networks, the dielectric loss of c‐PEI dielectric gradually decreased with the increasing content of TAP. Of particular significance was the c‐PEI dielectrics exhibiting improved Ud and η at high temperature. The maximum Ud of c‐PEI with 2 wt% TAP was 2.53 J/cm3 at 150°C, which was 24.8% higher than non‐cross‐linked PEI (2.11 J/cm3 at 150°C). This research provides an innovative strategy to achieve novel PEI dielectrics with improved Ud and η at high temperature.

Fundamental study on the preparation of insulating ceramics via the phase reconstruction of phosphate tailings

Insulating ceramics with anorthite and diopside as the main crystal phases were manufactured using phosphate tailings, coal gangue, and quartz as raw materials, which were fired at 1160–1190 °C for 2 h. The structure and micromorphology of the samples were investigated using X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy. Dense ceramic samples exhibited an apparent porosity of less than 0.3%, densities of 2.64–2.86 g/cm3, bending strength of 127.71–172.73 MPa, dielectric constants of 6.98–7.79, and dielectric losses of 0.0086–0.0024 at 20 °C and frequency of 1 MHz. The effects of impurity elements on ceramic properties are determined. The excellent electrical properties can be attributed to the solid solution of iron in the crystalline phases, such as diopside, which reduce leakage conductance in ceramics and alleviate the influence of relaxation and space charge polarization on the electrical properties of ceramics. This study provides a new strategy for preparing high-value insulating ceramics from solid waste.

Abnormal Time-Domain Current Spectrum of Inorganic Insulating Powder under DC Voltage

The total current of dielectrics under DC voltage consists of relaxation current and conduction current, which contains the information about the relaxation polarization and conduction. The time-domain spectrum (TDS) is an effective method to study the dielectric properties of insulating dielectrics. In this paper, the TDS method is also used to study the dielectric properties of the compressed inorganic hexagonal boron nitride (BN) and magnesium oxide (MgO) insulating powders. It is interestingly found that these inorganic insulating powders shows an abnormal TDS, where the current decreases monotonically to a certain level at first and then increases with time while in normal TDS the current decreases monotonically with time and finally reaches a steady value which is conduction current. The experiments verify that the abnormal phenomenon is attributed to the moisture absorption of powders during the testing process, which causes an increase in conductivity and leads to the increasing current at the end of testing time. The insulating powder cannot be regarded as a time-invariant system during the measurement, and the time-varying characteristic is mainly manifested in conduction. A time-domain least squares fitting method is presented and is effective to eliminate the deviation from normal TDS. The results of this paper provide a reference for dealing with abnormal TDS.

Constructing 3D Tent-Like frameworks in melamine hybrid foam for superior microwave absorption and thermal insulation

Taking serious electromagnetic pollution and practical application requirements into consideration, it’s imperative to develop multifunctional microwave absorption materials. In this work, the phenol–formaldehyde resin (PF) successfully adheres to melamine–formaldehyde foam (MF) as three-dimensional (3D) porous frameworks, and subsequently the substrate anchors few-layered MXene nanosheets by dripping-squeeze-drying procedures. According to the results, the hollow tent-like structure of MXene/PF@MF (MPM) shows a significant effect on microwave absorption capability, including extending heterogeneous interfaces for polarization relaxation and prolonging microwave propagation paths for energy dissipation. Based on the synergy of multiple components and rational structure, MPM exhibits a minimum reflection loss (RLmin) value of −58.8 dB at 2.2 mm and achieves an effective absorption bandwidth (EAB) of 6.74 GHz covering the entire Ku band. The microwave absorption mechanism reveals that the superior microwave absorption capability results from high conduction loss, polarization relaxation, multiple attenuations, and appropriate impedance matching. Furthermore, the MPMs possess lightweight features (32.7–48.7 g cm−3) and low thermal conductivity (0.0309–0.0318 W m−1 K−1) benefitting the unique 3D porous structure. Meanwhile, the low thermal conductivity endows MPMs with infrared stealth, which broadens the application in military fields. This work proposes a facile strategy for constructing highly efficient microwave absorbers with multiple functions.

Fire-resistant iron-based phosphates/phosphorus-doped carbon composites derived from phytic acid-treated metal organic frameworks as high-efficiency microwave absorbers

Considering the electromagnetic pollution in harsh environments, it is vital to prepare multifunctional microwave absorbers to broaden their application fields. Herein, fire-resistant iron-based phosphates/phosphorus-doped carbon composites were annealed from phytic acid-treated metal organic frameworks. Through tailoring the dosage of phytic acid used in the preparation process, composites with diverse morphologies, crystal structures, electric and microwave absorption properties are obtained. When the dosage of phytic acid used reaches 4 mL, the obtained composite, Fe2P4O12/phosphorus-doped carbon, possesses the best microwave absorption performance with a minimum reflection loss of −67.6 dB (2.0 mm) and an effective absorption bandwidth of 5.76 GHz (2.1 mm, 12.24–18 GHz). The microwave attenuation could be mainly attributed to the high conductivity brought by phosphorus-doped carbon, and polarization relaxations triggered by dipoles, functional groups, and unbalanced charges at interfaces. Specifically, the charge density distribution, obtained with density functional theory (DFT), suggests the occurrence of intense charge transfer and formation of internal electric field at P-carbon, O-carbon, and iron-based phosphates/phosphorus-doped carbon interfaces. Meanwhile, the as-prepared iron-based phosphates/phosphorus-doped carbon composites possess good fire-resistant property. The work provides a novel idea to construct multifunctional materials with high-efficient microwave absorption to broaden their application fields.

N-doped carbon nanofiber embedded with TiN nanoparticles: A type of efficient microwave absorbers with lightweight and wide-bandwidth

In this work, TiN-embedded in N-doped carbon nanofiber (TiN/NCNF) composites were synthesized by the electrospinning method and heat treatment process subsequently. The TiN/NCNF composites possess different TiN nanoparticles (TiNNPs) content, which can acquire by tuning the percentage of TiNNPs in the polyacrylonitrile precursor solutions. The study shows that TiN/NCNF composites hold more intense and tunable electromagnetic wave (EMW) absorption capabilities, as the embedded TiNNPs with more defects lead to enhanced electrical conductivity and cause room-temperature ferromagnetic. As a result, TiN/NCNF composites can achieve the well-matched impedance and contribute to significant electromagnetic wave attenuation capabilities due to their more interfacial polarization, defect dipole relaxation polarization, enhanced conductance loss, and magnetic loss caused by the defect, resulting in excellent microwave absorbing performance. When the mass fraction of the TiN/NCNF composites (S2 sample with nominal 3 wt% TiNNPs content) was only 30% in the absorbing coating, the optimal reflection loss (RL) value was achieved in − 45.19 dB at 15.6 GHz with a thickness of 1.91 mm, corresponding efficient absorption bandwidth (RL≤−10 dB) of 4.93 GHz. This work provides a novel method of realizing lightweight, wide-bandwidth, and efficient microwave absorbing characteristics of carbon fiber absorbents, using obtained particles from defect engineering strategies as loaded ones. As may be expected, the TiN/NCNF composites would have a significant potential application prospect as microwave absorbing materials.

Multi-interface-induced by regulating nanocomposite morphology and absorber design to achieve wideband electromagnetic wave absorber

The current study describes the fabrication of a bilayer microwave absorber made of magnetic Sr2FeReO6 (SRO) powder and a magnetoelectric nanocomposite formed of rod-like magnetic Sr2FeReO6 powder wrapped in polygonal SnS2 powder (SRSS), which was then annealed and analyzed. The analysis of phase constituents, as well as morphological and magnetic measurements, revealed that rod and polygonal particles with soft magnetic properties were successfully synthesized. Additionally, our findings showed that 30:70 wt ratio nanocomposite powders were unable to exhibit broad X-band frequency absorption capabilities. Due to the bi-layer absorber's rational design, the reflection loss was found to be increased and reached -33 dB at 10.3 GHz by covering practically the whole X-band frequency with only 2.5 mm of thickness. The prepared absorber's optimum design included SRSS nanocomposite powder as an absorbing layer with a 1.5 mm thickness and SnS2 powder as a matching layer. The exceptional electromagnetic wave dissipation performance of bi-layer samples compared to single-layer absorber samples may be the result of multiple interfaces being formed as a result of controlling component morphology and composition as well as the absorber's design, which enhanced critical absorbing factors like various polarization phenomena and relaxation losses. The research presented here suggests a simple method for enhancing microwave dissipation performance with a broad absorption band based on the development of heterojunction structures and the integration of various loss processes.

From the solid waste mixture of coal hydrogasification residue and red mud to efficient Fe3O4/C- and Fe/C-based composite microwave absorbents

Following the concept of sustainable development, magnetic particles/C-based composite microwave absorbing materials were prepared through reactions between two solid wastes: coal hydrogasification residue (CHR) and red mud (RM). At a fixed mass ratio of CHR to RM of 0.6:1, Fe3O4/C- and Fe/C-based composites could be obtained at 700 and 900 °C, respectively. A minimum microwave reflection loss of −48.3 dB and a largest effective absorption bandwidth of 4.5 GHz were achieved for the Fe/C-based composite with a simulated thickness of 1.5 mm. The Fe3O4/C-based composite exhibited slightly poorer performance because the fixed initial system could not guarantee impedance matching for both products. The strong intrinsic attenuation capacity of the materials mainly resulted from the dielectric loss, including conduction loss caused by graphite carbon as well as interfacial polarization relaxation loss arising from the numerous phase boundaries.

Facile synthesis of graphite-like carbon nitride/zinc oxide heterojunction for microwave absorption

Development of a thinner, wideband electromagnetic absorbing material that aims to address the growing electromagnetic pollution has becoming a hot topic. Herein, a heterojunction material consisting with 2-dimensional g-C3N4 and hierarchical flower shaped ZnO has been produced by a simple method, which exhibits the superior dielectric response ability. In details, the formed heterojunction with crossed energy structure benefits to the conductivity loss ability. Moreover, the as-prepared g-C3N4/ZnO with controlled interfaces possess the desirable interfacial polarization relaxation behavior, which may additional contribution for the dielectric loss. Owing to the improved conductive loss an interface polarization, the ultimately sample has a broad band EM absorption ability, with an effective absorption region of 5.3 GHz under a thin matched thickness of 1.5 mm. The method for designing of heterojunction-based material can be desirable candidate for the high-performance EM absorber.

Amorphous carbon engineering of hierarchical carbonaceous nanocomposites toward boosted dielectric polarization for electromagnetic wave absorption

Graphitic carbon materials are considered to be an important category of dielectric absorbers, but these materials are typically accompanied with poor impedance matching and unsatisfactory electromagnetic wave absorption (EMA) performance. Herein, engineered amorphous carbon is developed to produce hierarchical carbonaceous nanocomposites (HCNs) via crystallization-induced interfacial polymer self-assembly and carbonization, which is aimed at boosting dielectric polarization for enhancing EMA capability. By optimizing the polymer precursor species, graphitic carbon matrix, and carbonization temperature, the hierarchical architecture and N-bonding configurations, containing pyridinic N, pyrrolic N, and graphitic N, can be regulated for polarization relaxation loss and conductive loss. In addition, multiple reflection and scattering behavior are also beneficial for increasing EMA capability. Compared with those of the pure graphitic carbon matrix and related HCNs, the minimum reflection loss (RLmin) of MWCNTs coated with polyimide-derived amorphous carbon at 700 °C (MWCNT/C(PI-EDA)-700) is −45.7 dB at a matched thickness of 3.6 mm with a filler loading of only 5 wt%, and its effective absorption bandwidth (EAB, RLmin < −10 dB) is 3.9 GHz. In summary, based on the systematic analysis of 16 carbonaceous absorbers, in this study, not only the intrinsic EMA mechanism of HCNs is revealed, but also new avenues for designing and fabricating high-efficiency dielectric absorbers are opened.

(Digital Presentation) Dielectric and Vibrational Spectroscopic Study on Asymmetric Quaternary Phosphonium-Based Ionic Liquids

Ionic liquids (IL) have a great potential of applications in electrochemical devices such as electrolytes for fuel cells. In particular, quaternary phosphonium cation-based ionic liquids (P-ILs) is much suitable due to lower viscosity and better ionic conductivity compared with corresponding quaternary ammonium cation-based ionic liquids (A-ILs). Over the past decade, fundamental properties of P-ILs have been investigated by viscometry, calorimetry, spectroscopy, calculation, and so on. However, little is known about molecular mechanism for such better potential of P-ILs. The present study aimed to reveal the relationship between molecular structure and macroscopic material properties of P-ILs in terms of alkyl chain asymmetry. The P-ILs used in this study were prepared by quadrification of trialkylphosphine followed by ion exchange with bis(trifluoromethanesulfonyl)imide (TFSA) anions. We named P-ILs based on the number of alkyl chain length. For example, P2225 means triethyl(penta)phosphonium cation. In this study, we used P2225-TFSA, P2228-TFSA, and P222(12)-TFSA. We conducted temperature-variable broadband dielectric spectroscopy between 20 Hz and 100 MHz. We also carried out Raman spectroscopy (laser excitation at 532 nm) and THz spectroscopy. The obtained complex dielectric spectra were dominated by (i) electrode polarization, (ii) ionic conduction, and (iii) reorientational relaxation, depending on the frequency and temperature. The spectra at the frequency regions between ionic conduction and reorientational relaxation were well-fitted with a Havriliak-Negami dielectric relaxation function, superimposed with a conductivity term. Thus, we determined both ionic conductivity (σdc) and relaxation time for structural relaxation (τHN) of ionic liquids. Although the σdc for all of the P-ILs used in this study exhibited similar Vogel-Fulcher-Tamman-type temperature dependence, the σdc slightly decreased with increasing the asymmetric alkyl chain length. Such temperature dependence was also observed in τHN, meaning that translational dynamics partly coupled with segmental dynamics. This result is consistent with that internal motion of the alkyl chains should depend on the chain length. Raman and THz spectroscopy provided an information on molecular structure (such as conformation) and inter- and intra-molecular interaction between anions and cations. In the presentation, we will describe the relationship of charge carrier transportation with ion conformations and intermolecular structures.