Dielectric capacitors are receiving increasing attention due to the high-power density and fast charge–discharge speed. However, defects are inevitably induced during the preparation process and then weaken the breakdown strength, thereby limiting their energy density. The phenomenon gives rise to self-healing technology. The discovery of sol–gel-derived aluminum oxide with electrolysis and dielectric dual-characteristic provides a novel, simple and cost-effective self-healing method to heal defects and enhance energy density. In this paper, we systematically reviewed the current self-healing technologies and the important progress of electrolysis and dielectric co-existence dielectrics. Finally, we outlook the electrolysis and dielectric co-existence dielectrics and potential challenge.