This disclosure relates to methods and apparatus for enhanced dielectric properties for electrolytic capacitors to store energy in an implantable medical device. One aspect of the present subject matter includes a method for manufacturing a capacitor adapted to be disposed in an implantable device housing. An embodiment of the method includes providing a dielectric comprising aluminum oxide and doping the aluminum oxide with an oxide having a dielectric constant greater than aluminum oxide. Doping the aluminum oxide includes using sol-gel based chemistry, electrodeposition or atomic layer deposition (ALD) in various embodiments.