Polymer nanocomposites consisting of materials such as ionic polymers and nano‐ceramic fillers are widely used in high‐power lithium‐polymer batteries because of their high ionic conductivity, good mechanical strength, electrothermal stability, and better compatibility with electrodes. Nanocomposite films of polyvinylidene fluoride (PVDF)/lithium titanium oxide Li₄Ti₅O₁₂ (LTO) with different volume fractions of LTO nanoparticles (NPs) are prepared via casting method. The DSC thermograms revealed a slight decrease in the melting temperature T_m and a noticeable reduction in the degree of crystallinity with increasing the volume fraction of LTO. This decrease is confirmed by the increment in the relative fraction of β‐phase in the PVDF matrix calculated from both XRD and FTIR. SEM images indicated the growth of porous globular structures in the presence of LTO NPs. Besides, the hydrophilicity of PVDF is improved by incorporating LTO NPs. The dielectric constant ε′(ω), loss ε″(ω), ac conductivity σ_ac(ω), complex impedance Z^*(ω), and Nyquist plots of PVDF/LTO nanocomposites are investigated in the temperature range from 303 to 413 K and frequency range from 100 Hz to 1 MHz. The σ_ac(ω) and frequency exponent s are found to obey the correlated barrier hopping model. Values of the frequency exponent s and the charge carriers binding energy W_m for the studied nanocomposite films decrease with rising temperature and LTO addition. Furthermore, dielectric constant ε′(ω), loss ε″(ω), and ac electrical conductivity σ_ac(ω) of films are found to be strongly frequency and temperature dependent. The localized states density N(E_F) at the Fermi level increase with increasing temperature and LTO NPs volume fraction, resulting in the W_m decrease and the enhancement of the ac electrical conductivity σ_ac(ω). The impedance spectrum and Nyquist plots provide an insight into the influence of LTO vol% in the resistive and capacitive characteristics of PVDF/LTO films. These results recommend the choice of LTO NPs as dopants to enhance the electrical properties of the PVDF matrix to be used in high‐power lithium‐ion batteries and electronic devices.

中文翻译：

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用于高功率锂聚合物电池的多孔PVDF / Li4Ti5O12纳米复合膜的结构，热学和介电性能

由离子聚合物和纳米陶瓷填料等材料组成的聚合物纳米复合材料因其高离子导电性，良好的机械强度，电热稳定性以及与电极的更好兼容性而广泛用于高功率锂聚合物电池。通过流延法制备了不同体积分数的LTO纳米颗粒（NPs）的聚偏二氟乙烯（PVDF）/氧化钛钛Li ₄ Ti ₅ O ₁₂（LTO）纳米复合膜。DSC热分析图显示熔融温度T _m略有降低随着LTO体积分数的增加，结晶度明显降低。通过XRD和FTIR计算得出的PVDF矩阵中β相的相对分数的增加证实了这种减少。SEM图像表明在LTO NP存在下多孔球状结构的生长。此外，通过引入LTO NP提高了PVDF的亲水性。介电常数ε '（ω），损耗ε “（ω），交流电导率σ_交流（ω），复阻抗ž ^*（ω）在303至413 K的温度范围和100 Hz至1 MHz的频率范围内研究了PVDF / LTO纳米复合材料的奈奎斯特图。所述σ_交流（ω）和频率指数小号被发现服从相关屏障跳频模型。研究的纳米复合薄膜的频率指数s和电荷载流子结合能W _m的值随着温度的升高和LTO的添加而降低。此外，介电常数ε '（ω），损耗ε “（ω），和交流电导率σ_交流发现薄膜的（ω）与频率和温度密切相关。局部状态密度Ñ（Ë _˚F）在随着温度的升高和LTO的NP体积分数的费米能级增加，导致在W¯¯_米降低和的提高交流电导率σ_交流（ω）。阻抗谱和奈奎斯特图可洞察LTO vol％对PVDF / LTO薄膜的电阻和电容特性的影响。这些结果建议选择使用LTO NP作为掺杂剂，以增强用于大功率锂离子电池和电子设备的PVDF基质的电性能。