High Conduction Band Inorganic Layers for Distinct Enhancement of Electrical Energy Storage in Polymer Nanocomposites

Abstract

Dielectric polymer nanocomposites are considered as one of the most promising candidates for high-power-density electrical energy storage applications. Inorganic nanofillers with high insulation property are frequently introduced into fluoropolymer to improve its breakdown strength and energy storage capability. Normally, inorganic nanofillers are thought to introducing traps into polymer matrix to suppress leakage current. However, how these nanofillers effect the leakage current is still unclear. Meanwhile, high dopant (> 5 vol%) is prerequisite for distinctly improved energy storage performance, which severely deteriorates the processing and mechanical property of polymer nanocomposites, hence brings high technical complication and cost. Herein, boron nitride nanosheet (BNNS) layers are utilized for substantially improving the electrical energy storage capability of polyvinylidene fluoride (PVDF) nanocomposite. Results reveal that the high conduction band minimum of BNNS produces energy barrier at the interface of adjacent layers, preventing the electron in PVDF from passing through inorganic layers, leading to suppressed leakage current and superior breakdown strength. Accompanied by improved Young’s modulus (from 1.2 GPa of PVDF to 1.6 GPa of nanocomposite), significantly boosted discharged energy density (14.3 J cm−3) and charge–discharge efficiency (75%) are realized in multilayered nanocomposites, which are 340 and 300% of PVDF (4.2 J cm−3, 25%). More importantly, thus remarkably boosted energy storage performance is accomplished by marginal BNNS. This work offers a new paradigm for developing dielectric nanocomposites with advanced energy storage performance.

Application of Nanocomposite Energy Storage Materials in Green Building Design

“…After ball milling, the agglomeration of CNTs was improved, and the dispersibility in stearic acid was significantly increased compared with untreated CNTs. However, after oxidative modification with mixed acid, the dispersibility of carbon nanotubes in stearic acid is the best, there is no obvious agglomeration phenomenon, and it is completely covered by stearic acid [ 13 , 14 ].…”

Optimization strategies for energy storage properties of polyvinylidene fluoride composites

“…PVDF 层极化到 PSF 层，当温度下降时，杂质离子大量停留在在 PSF 层，多层 结构损耗系数为 0.003，与纯 PVDF 相比有大幅度下降。由此可见不同层间的界 面屏障可以阻挡聚合物内部杂质离子的迁移，从而抑制电导损耗。 对于聚合物界面处产生的电导损耗，引入宽带隙无机层如 BN、SiO 2 可有 效减小电荷注入与迁移。Yang [78] 构建了二维石墨烯核壳纳米片(GO@SiO 2 )作为 PVDF 夹层结构,GO@SiO 2 纳米片紧密排列并沿垂直于电场的方向定向，在一定 程度上提升了击穿，降低了损耗。 Chen 等 [79] 将 BN 转移到 P(VDF-CTFE)薄膜 上,如图 9(e)所示，其损耗值 0.028 低于纯聚合物的 0.031，在 80°C 时，最大 能量密度可达 6.38 J/cm 3 ，是原始 P (VDF-CTFE) (0.78 J/cm 3 )的近 8 倍，充放电 效率也提升了近 1 倍(图 9(f))。 Li [80] 制备了含 4 层 MXene 和 5 层 PVDF 多层 结构，多层结构具有极低的介电损耗(0.028，远小于纯 PVDF)，多层结构最大 储能密度可达 7.4J/cm 3 ,充放电效率为 75%，高于纯 PVDF 的 3.2J/cm 3 的储能密 度与 65%的充放电效率。Zhu [81] 制备了夹层为沿面内方向排列的纳米级 BNNS 的 PVDF 复合薄膜，损耗值 0.069 较于纯 PVDF 的 0.057 有所降低，复合膜最大 储能密度为 14.3J/cm 3 , 效率最高可达 73%，分别比纯 PVDF 提高了 175%和 152%。Zhu [82] 制备了由两层 BN 层与 3 层 PVDF 层构成的多层结构膜，多层结 构膜损耗为 0.067，相比于纯 PVDF 的 0.094 有一定程度的下降，其最大储能密 度为 14.3J/cm 3 ,充放电效率为 75%，分别为纯 PVDF(U e =4.2J/cm 3 , η=25%)的 340%与 300%。这种多层结构可以有效地阻止整个薄膜形成导电网络，从而抑 制了电导损耗。 然而，需要注意的是，填料本身的结构设计以及在复合介质中的分布和取 向等都会对能量损耗有很大影响，进一步优化制备工艺，实现规模化生产，对 复合介电材料的发展具有重要意义。而在构建多层结构方面，如线性电介质有 机层种类的选择，宽带隙无机层制备工艺的选择，都需要综合考虑仔细比较， 以进一步降低介电损耗，提升充放电效率。 图 9(a)PVDF/ P(VDF-TrFE-CFE)共混膜的储能密度与充放电效率 [69] ;(b) GLC/P(VDF-HFP)电导损耗 [75] ;(c)不同钛酸锶钡含量下单层膜与三层膜介 电损耗;(d)TNF 介电损耗降低示意图 [76] ;(e)BN 涂层 P(VDF-CTFE)流程 示意图;(f)自组装薄膜与 P(VDF-CTFE)储能密度与充放电效率 [79] Fig. 9(a) Energy storage density and charge/discharge efficiency of PVDF/ P(VDF-TrFE-CFE) blended films [69] ; (b) GLC/P(VDF-HFP) conductive loss [75] ; (c) dielectric loss of monolayer and trilayer films with different barium strontium titanate content;(d) schematic diagram of TNF dielectric loss reduction [76] ; (e) schematic diagram of BN-coated P(VDF-CTFE) process; (f) energy storage density and charge/discharge efficiency of self-assembled films with P(VDF-CTFE) [79] 6 总结与展望 Corresponding author.…”

Laminated ferroelectric polymer composites exhibit synchronous ultrahigh discharge efficiency and energy density via utilizing multiple-interface barriers

“…18 Compared to zero-dimensional (0D) nanoparticles and onedimensional (1D) nanowires/nanobers/nanotubes, two dimensional (2D) ceramic nanosheets were introduced to promote the dielectric and energy storage capabilities of hierarchically structured polymer dielectrics because of higher dielectric constants and favorable insulating capability along their through-thickness direction. [19][20][21][22] For instance, Zhang et al prepared two symmetric tri-layered structured polyvinylidene a Shaanxi Key Laboratory of Optoelectronic Functional Materials and Devices, School of Materials Science and Chemical Engineering, Xi'an Technological University, Xi'an 710032, China b School of Electronic Information and Articial Intelligence, Shaanxi University of Science and Technology, Xi'an 710021, China. E-mail: yuanqibin-sust@163.com c Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA.…”

“…Compared to zero-dimensional (0D) nanoparticles and one-dimensional (1D) nanowires/nanofibers/nanotubes, two dimensional (2D) ceramic nanosheets were introduced to promote the dielectric and energy storage capabilities of hierarchically structured polymer dielectrics because of higher dielectric constants and favorable insulating capability along their through-thickness direction. 19–22 For instance, Zhang et al prepared two symmetric tri-layered structured polyvinylidene fluoride (PVDF)-based nanocomposites by adding KNbO 3 (KNO) nanosheets. 23 The results indicate that the tri-layered structured nanocomposite with a very low concentration of 1 vol% KNO nanosheets exhibited a high U e of 19.97 J cm −3 and a η of approximately 55% at 539 MV m −1 .…”