Solid State Ionics最新文献

All-solid-state lithium batteries are in great demand, but the problem of high interfacial resistance between the cathode and solid electrolyte needs to be addressed. The effect of heat treatment of the cathode half-cells on the LiFePO₄ | Li₇La₃Zr₂O₁₂ interfacial resistance was studied. According to differential scanning calorimetry, the interaction between the cathode material and Li₇La₃Zr₂O₁₂ begins at 699 °C. It was also shown via X-ray diffraction data that increasing the annealing temperature from 600 to 700 °C leads to the appearance of impurities related to the interaction of the solid electrolyte with LiFePO₄ (La₂Zr₂O₇ and LaFeO₃). A scanning electron microscopy study demonstrated that LiFePO₄ has good contact with ceramic electrolyte without and after heat treatment. The lowest resistance at the LiFePO₄ | Li₇La₃Zr₂O₁₂ interface (∼2000 and 30 Ohm cm² at 100 and 300 °C, respectively) was obtained for half-cells without heat treatment. Thus, heat treatment leads to an increase in the interfacial resistance caused by the interaction of LiFePO₄ with Li₇La₃Zr₂O₁₂

A series of solid polymer electrolyte films were prepared using a casting solution with a polymer matrix comprising 49% poly(methyl methacrylate)-grafted natural rubber (MG49). These films incorporated binary lithium salts: lithium tetrafluoroborate (LiBF₄) combined with either lithium trifluoromethanesulfonate (LiTf) or lithium iodide (LiI). These films' dielectric properties and ion association behavior were examined using potentiostatic electrochemical impedance spectroscopy (EIS) and Fourier transform infrared (FTIR) deconvolution. The key findings demonstrated that the increase in both the dielectric constant (ɛ_r) and dielectric loss (ɛ_i) was significantly correlated with enhanced ionic conductivity, reaching a value of 1.89 × 10⁻⁶ S cm⁻¹, which was attributed to enhanced ionic and segmental mobility. A peak observed in the M_i versus frequency plot confirmed the ionic conductor behavior. The (30:70) ratio of LiBF₄ to LiI exhibited the highest performance, with superior ionic conductivity, dielectric behavior, tangent loss, number of charge carriers, mobility, and diffusion coefficient, surpassing the performance of the single salt or LiBF₄ to LiTf. This indicates that the combination of LiBF₄ and LiI is particularly effective for applications requiring improved dielectric properties.

In the industry of high-temperature sensors and actuators, materials capable of delivering high ferroelectric, dielectric, and specifically stable/high piezoelectric performances above 1000 °C are in demand. Hence, perovskite-like layered structured (PLS) have gained popularity due to their high Curie temperature (T_C) and ferroelectric properties, but the low piezoelectric coefficient (d₃₃) at high temperature (>1000 °C) is the problem statement to be explored and improved. Herein this research, La_1.97(LiCe)_0.03Ti₂O₇:xwt%MnO₂ (LLCTO:xMn) with x = 0–0.3 ceramic series has been explored to study the ultra-high structural, ferroelectric, electric, dielectric, and piezoelectric properties. Among all compositions, LLCTO:0.2Mn ceramic has demonstrated ultra-high performances with remnant polarization (P_r) of ∼1.84 μC/cm², piezoelectric co-efficient (d₃₃) of 9 pC/N, resistivity of ∼10¹¹ Ω.cm, relative dielectric constant (ɛ_r) of 46, and minor dielectric loss (tanδ) of 0.17 which are much improved compared to pure La₂Ti₂O₇ (LTO) and pristine La_1.97(LiCe)_0.03Ti₂O₇ (LLCTO) ceramics. The LLCTO:0.2Mn ceramic has exhibited the high T_C of 1415 °C. Moreover, thermally stable multifunctional performances are measured where LLCTO:0.2Mn ceramic has demonstrated a high d₃₃ of ∼8.5 pC/N at 1200 °C and resistivity of ∼2.4 × 10⁷ Ω.cm even at 1000 °C, which are much better than the earlier reports. From the analysis, LLCTO:0.2Mn ceramic has demonstrated the potential to be utilized in high-temperature (>1000 °C) piezoelectric devices.

N-doped hierarchical porous carbon sheet was prepared through calcination of a sodium alginate film precursors containing Zn-2-methylimidazole coordination complex. The film precursors could be obtained at room temperature. The introduction of coordination complex cannot cause the change of sheet morphology, but it can promote the generation of large pore structure. Due to the hierarchical porous structure and N doping, the carbon materials present excellent electrochemical behaviors when used as supercapacitor electrode materials. It exhibited a high specific capacitance of 210.4 F g⁻¹ at 2 A g⁻¹ in a two-electrode system with a capacitance retention of 83.4% over 10,000 cycles.

Electrochromic materials have been widely applied in smart windows due to their color conversion and adjusting indoor solar radiation abilities. The researches on electrochromic properties of tungsten bronzes with near-infrared light absorbing abilities are important to obtain multifunctional smart windows. Here, nano potassium tungsten bronze K_xWO₃ with space group P6₃/mcm has been synthesized to study the effects of crystal structures and valence states of W ions on its electrochromic properties. By altering the composition of reaction solution in solvothermal method, the K content x of samples can be controlled together with the adjustments in sizes of hexagonal and trigonal channels in the crystal structure and valence states of W ions. The maximum optical modulation and coloration efficiency are achieved for the maximum x. The enhanced electrochromic performance mainly benefits from the synergistic size effects of hexagonal and trigonal channels.

Polyphosphate, as the cathode material of sodium ion battery(SIB) has the advantages of good structural stability and long service life, but suffer from poor conductivity and low specific capacity. The doping of heteroatom and coating of carbon are considered to be two effective measures to overcome its shortcomings. In this work, the Bismuth(Bi)-doped and carbon-coated materials Na₃V_2-xBi_x(PO₄)₂F₃/C with various Bi³⁺ doping levels(x = 0.03,0.05,0.07) were prepared by a facile sol-gel method combined high temperature calcination. The effect of Bi³⁺ doping on the electrochemical properties was systematically investigated. The Na₃V_1.95Bi_0.05(PO₄)₃F₃/C showed the best electrochemical performance with the specific capacities of 107.4, 94.3, 92.4, 86.2 mAh·g⁻¹ at 0.1 A·g⁻¹(0.78C), 0.2 A·g⁻¹(1.56C), 0.5 A·g⁻¹(3.9C), 1.0 A·g⁻¹(7.8C) respectively, and 90.4% of specific capacity was retained after 100 charge/discharge cycles, which has a greatly increase compared with the Na₃V₂(PO₄)₃F₃ material. This is attribute to the improving of the conductivity, the diffusion capacity and the structural stability of the material by Bi-doping and carbon coating.

Developing effective strategies to promote the sodium-ion storage performance of hard carbon anodes is essential for its practical application in sodium-ion batteries. The carbonization process plays a crucial role in regulating the microstructure of hard carbon. Conventional carbonization methods of slow-heating have hit a bottleneck in structural controls of hard carbon materials. Herein, hard carbon with high-rate and low-temperature sodium storage capability is ultrafast synthesized by flash Joule heating. Compared to the hard carbon synthesized by conventional slow-heating, the hard carbon synthesized by flash Joule heating has smaller particle size, larger interlayer spacing, and larger closed-pores leading to superior performance. This work provides a simple and effective method of boosting sodium-ion storage performance for hard carbon materials.

Poly(thiophene-3‑boronic acid) (PTBA) was studied as a promising active material for aqueous environments in this paper. Using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the solubility and electrochemical behavior of it was studied in a range of aqueous solutions. Fourier Transform Infrared Spectrometry (FTIR) results verify the successful synthesis. PTBA shows promising solubility qualities in certain pH ranges, especially in alkaline solutions. However, among alkaline, neutral, and acidic environments the best environment for redox properties of aqueous 1 mM PTBA is the neutral one. The peak current (i_p) of 1 mM PTBA for 100 mV/s in the neutral environment is 0.01 mA and half peak potential (E_p/2) is −0.1 V (vs Ag/AgCl). Diffusion coefficient of PTBA is found as 4.97 × 10⁻⁸ cm²/s. The impedance tests also confirm that the neutral solvent decreases the charge transfer resistance.

The mesoporous electrode material offers a high surface area, excellent porous texture, and optimal pore-size distribution, facilitating increased active sites for ion accretion and enhanced ionic diffusion rates. NiMoO₄, TiS₂, and their composites such as NT-1, NT-2, NT-3, and NT-4 composites have been prepared by hydrothermal approach to enhance the capacitance of supercapacitor electrodes. Different methodologies have been employed to analyze the optical, morphological and structural characteristics of the synthesized materials. X-ray diffraction was utilized to assess the crystalline nature of both the pristine materials and composites. Scanning electron microscopy examination confirmed the formation of mesoporous and irregular nanoparticles with sizes ranging from 50 to 100 nm. Fourier-transform infrared spectroscopy was employed to examine the stretching vibrations of the prepared samples. Through photoluminescence (PL) analysis, the energy band gap of the NT-1 composite was decisive to be 2.78 eV. The NT-1 composite exhibits an impressive specific capacitance of 1257.14 Fg⁻¹ at 1 Ag⁻¹, attributed to its huge surface area, efficient charge transfer, and synergistic effect while demonstrating remarkable stability after 5000 cycles with 92% capacitance retention. Therefore, NT-1 binary metal sulfide composite unleashes high-performance supercapacitors with remarkable specific capacitance and cyclic stability.

In-house electrospun La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ (LSCF) nanofibers have been tested through synchrotron x-ray diffraction and electrochemical impedance spectroscopy (EIS) in the 823–1173 K range, namely in the operating window of intermediate-temperature solid oxide fuel cells. Identical tests have been carried out on commercial LSCF powders, as a control sample. The results demonstrate that the electrospinning manufacturing procedure influences the crystalline properties of the perovskite. The rhombohedral structure (R), stable at room temperature, is retained by nanofibers throughout the whole temperature range, while a rhombohedral to cubic transition (R→C) is detected in powders at ⁓1023 K as a discontinuity in the rhombohedral angle α, accompanied by an abrupt change in oxygen occupation and microstrain. EIS data have a single trend in the nanofibers Arrhenius plot, and two different ones in powders, separated by a discontinuity at the structural transition temperature. Thus, a striking parallel is demonstrated between the variation with temperature of crystallographic features and electrochemical performance. Interestingly, this parallel is found for both nanofiber and granular electrodes. This opens up questions and new perspectives in attributing activation energies derived from EIS tests of LSCF materials to electrochemical processes and/or crystal structure variations.