Synergistic thermo-electro-mechanical coupling effects on interface-space charge dynamics in 800 V EV composite insulation

The rapid proliferation of 800 V high-voltage electric vehicles (EVs) has imposed stringent demands on insulation systems to endure the synergistic effects of thermo-electro-mechanical coupling (TEMC). However, the aging mechanisms of high thermal conductivity composites, which are pivotal for efficient heat dissipation in these advanced EV systems, remain inadequately understood. This study addresses this critical knowledge gap by systematically investigating the electrical aging behavior of h-BNNTs/epoxy composites (10 wt.% h-BNNTs) under TEMC conditions using a state-of-the-art, self-developed multi-field coupling test system. This innovative system integrates precise control of temperature gradients (Δ T  = 55 °C/mm), electric fields (15 kV/mm), and mechanical vibration (10–2000 Hz, 5 g) to accurately replicate real-world operating environments.A comprehensive suite of cross-scale characterization techniques, including dielectric spectroscopy, pulsed electro-acoustic (PEA) space charge measurement, synchrotron X-ray micro-computed tomography (μCT), and atomic force microscopy–infrared (AFM–IR) spectroscopy, was employ