High-voltage MIM-type aluminum electrolytic capacitors

Metal-insulator-metal aluminium electrolytic capacitors （MIM-AECs） combine high capacity-density and high breakdown field strength of solid AECs with high-frequency responsibility,wide workingtemperature window and waterproof properties of MIM nanocapacitors.However,interfacial atomic diffusion poses a major obstacle,preventing the high-voltage MIM-AECs exploitation and thereby hampering their potential and advantages in high-power and high-energy-density applications.Here,an innovative high-voltage MIM-AECs were fabricated.The AlPO4 buffer layer is formed on AlO（OH）/AAO/Al surface by using H3PO4 treatment,then a stable van der Waals （vdW） SnO2/AlPO4/AAO/Al multilayer was constructed via atomic layer deposition （ALD） technology.Due to higher diffusion barrier and lower carrier migration of SnO2/AlPO4/AAO interfaces,Sn atom diffusion is inhibited and carrier acceleration by electric field is weakened,guaranteeing high breakdown field strength of dielectric AAO and avoiding local breakdown risks.Through partial etching to hydrated AlO（OH） by H3PO4 treatment,the tunnel was further opened up to facilitate subsequent ALD-SnO2 entry,thus obtaining a high SnO2 coverage.The SnO2/AlPO4/AAO/Al capacitors show a comprehensive performance in high-voltage （260 V）,hightemperature （335℃）,high-humidity （100%RH） and high-frequency response （100 k Hz）,outperforming commercial solid-state AECs,and high-energy density （8.6μWh/cm2）,markedly exceeding previously reported MIM capacitors.The work lays the foundation for next-generation capacitors with highvoltage,high-frequency,high-temperature and high-humidity resistance.