Dielectric Energy Storage Performance Of PVDF-based Polymer Composites Adding Two-Dimensional Nanosheets

Dielectric capacitors have the advantages of low loss,high operating voltage,and fast discharge speed compared with other capacitors.However,current capacitors on the market are difficult to meet the requirements,ceramic capacitors have low breakdown voltage and high loss;polymer capacitors have small electrical displacement and cannot achieve high energy storage density.This is mainly due to the opposite relationship between the dielectric permittivity and the breakdown strength of the material,that is,the higher the dielectric permittivity,the sharp drop in the breakdown voltage of the material.The study found that adding other inorganic particles such as ceramic particles to the polymer material to form a composite material can effectively increase its electrical displacement value,but directly adding it will also greatly reduce the voltage breakdown strength and fail to achieve the desired effect.How to improve the electrical displacement of materials while maintaining a high voltage breakdown strength is the focus of this paper.In this paper,composites formed by PVDF-based/two-dimensional inorganic particles were prepared.The dielectric energy storage properties of the composites were tested.The relationship between the structure and the addition of fillers on the properties of the materials was investigated.The main research contents are as follows:1.A plate-like Bi₄Ti₃O₁₂ powder modified with dopamine hydrochloride is added to the polymer to prepare PVDF/P-Bi₄Ti₃O₁₂ composite material,and a granular-like Bi₄Ti₃O₁₂ modified by surface modification of dopamine hydrochloride is added to the polymer.The prepared PVDF/G-Bi₄Ti₃O₁₂ composites were used as a comparison group to test and analyze the electrical properties of the two composite materials.The comprehensive performance of PVDF/P-Bi₄Ti₃O₁₂ is better than PVDF/G-Bi₄Ti₃O₁₂.Finally,the composite of the optimal composition was selected for fatigue testing.2.The platy inorganic material SrTiO₃ having a higher dielectric permittivity is added to the polymer substrate to form a PVDF/SrTiO₃ composite material,and the SrTiO₃ is also subjected to a surface modification treatment of dopamine.Testing the electrical properties of composite materials,the dielectric properties of the materials have improved significantly,and the energy storage performance at low electric field strengths has performed well.Select the best performing composite for fatigue testing.3.Finally,the composite inorganic particles MoS₂@BNNS using molybdenum disulfide and boron nitride nanosheets to form a nano-laminated structure are studied.The PVDF/MoS₂@BNNS composite material is formed by blending it with polymer PVDF.The dielectric properties and breakdown strength improved simultaneously.By studying its electrical properties,the highest releasable energy density is 14.71 J/cm3.The material is also subjected to a fatigue test to test the performance stability of the material.