Key Laboratory of Shanxi Province 1 article published in JoVE Engineering Application of a Coupling Agent to Improve the Dielectric Properties of Polymer-Based Nanocomposites Haotian Li1,2,3, Dong Zhang4, Zechen Li4, Leyi Li5, Jiachen Liu1, Yugui Li1,2 1Taiyuan University of Science and Technology, 2Heavy Machinery Engineering Research Center of the Ministry of Education, 3Laboratory of Magnetic and Electric Functional Materials and Applications, The Key Laboratory of Shanxi Province, 4Beijing Institute of Aerospace System Engineering, 5Department of Electrical and Information Engineering, Sichuan College of Architectural Technology Here, we demonstrate a simple and low-cost solution-casting process to improve the compatibility between the filler and the matrix of polymer-based nanocomposites using surface modified BaTiO3 fillers, which can effectively enhance the energy density of the composites.