1：Experimental Design and Method Selection:

In-situ aniline polymerization was used to create BT@PANI nanoparticles with controllable shell thickness. Solution casting method was employed to prepare PEN/BT@PANI nanocomposite films.

2：Sample Selection and Data Sources:

BaTiO3 nanoparticles (<100 nm) were used as core, with varying amounts of aniline (

3：1, 2, 3 mL) to control shell thickness. PEN was synthesized from 2,6-dichlorobenzonitrile and biphenol. List of Experimental Equipment and Materials:

Equipment includes ultrasonicators, ice-water baths, XPS (ESCA 2000), FTIR (8400S), XRD (RINT2400), UV-vis (TU1800), SEM (6490LV), DSC (Q100), TGA (Q50), universal testing machine (CMT6104), dielectric withstand voltage tester (ZJC-50KV), LCR meter (TH 2819A). Materials include BaTiO3, aniline, ammonium persulfate, DCBN, BP, K2CO3, solvents, NMP.

4：Experimental Procedures and Operational Workflow:

BaTiO3 was dispersed in water, aniline/HCl and ammonium persulfate solutions were added for polymerization at 0-5°C for 18h. Nanocomposite films were cast from NMP solutions, dried, and characterized.

5：8h. Nanocomposite films were cast from NMP solutions, dried, and characterized. Data Analysis Methods:

5. Data Analysis Methods: Data analyzed using TGA for weight loss, FTIR and XPS for chemical structure, SEM for morphology, DSC and TGA for thermal properties, mechanical testing for strength, dielectric measurements for permittivity and loss, and energy density calculated using Equation (1).