Poly (vinylidene fluoride) (PVDF) based polymers are good candidates for high-power energy storage in dielectric capacitors. So far, most studies reporting PVDF with high energy density are based on solution casting, a method ill-suited for large-scale production. In this work, we develop PVDF films with high crystallinity (47%) and ultrahigh β-phase (∼97%) using Hot Rolling Press (HRP). During HRP, the crystallinity, fraction of β-phase, internal stress, and the piezoelectric coefficient d increased with rolling temperature. The anisotropic stress imposed by two rollers led to a highly preferred orientation of the HRP film along the rolling direction. Notably, the HRP film exhibits an enhanced field-induced polarisation P value (0.16 C m) compared to conventional PVDF films (0.10 C m), with an energy density of 32.6 J cm at 871 kV mm. The good low field dielectric ( ∼19 @ 1 kHz) and piezoelectric (d ∼30 pC N) properties with high-temperature stability (up to 100 °C), and its suitability for in-line continuous production, make HRP PVDF films promising for low field dielectric and piezoelectric applications.

中文翻译：

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增强场致极化热轧压制 PVDF 薄膜的加工和表征

聚偏二氟乙烯 (PVDF) 基聚合物是介电电容器中高功率储能的良好候选者。到目前为止，大多数报道高能量密度PVDF​​的研究都是基于溶液铸造，这种方法不适合大规模生产。在这项工作中，我们使用热轧机 (HRP) 开发了具有高结晶度 (47%) 和超高 β 相 (∼97%) 的 PVDF 薄膜。在HRP过程中，结晶度、β相分数、内应力和压电系数d随着轧制温度的增加而增加。两个辊施加的各向异性应力导致 HRP 薄膜沿滚动方向高度择优取向。值得注意的是，与传统的PVDF薄膜（0.10 C m）相比，HRP薄膜表现出增强的场致极化P值（0.16 C m），在871 kV mm下的能量密度为32.6 J cm。良好的低场介电 (∼19 @ 1 kHz) 和压电 (d ∼30 pC N) 性能以及高温稳定性（高达 100 °C），及其适合在线连续生产，使得 HRP PVDF 薄膜具有广阔的前景适用于低场介电和压电应用。