Aluminum Electrolytic Capacitor Aging for Stable Oxide and Low Leakage
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Solution Overview
Problem
Aluminum electrolytic capacitors in implantable cardioverter defibrillators require frequent maintenance due to dielectric relaxation and electrolyte loss, leading to reduced energy density and shortened battery life.
Innovation Solution
A two-step aging process for aluminum electrolytic capacitors involving impregnation with different electrolytes and controlled voltage and temperature conditions to grow a stable oxide layer, reducing the need for maintenance and extending battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum electrolytic capacitors are stored at room temperature without charging, then capacitor deformation occurs due to dielectric relaxation and electrolyte loss, but frequent maintenance charge cycles are required which shorten battery life
Solution Approach 1:
The capacitor undergoes an aging process before implantation that pre-grows the oxide layer and stabilizes the dielectric structure. This preliminary action reduces subsequent deformation and maintenance needs during the device's operational life, thereby extending battery life while maintaining reliability
2Manufacturing precision
If a single aging process is used, then the oxide layer grows but electrolyte is lost due to hydrogen evolution, requiring re-impregnation which increases process complexity
Solution Approach 1:
The aging process is divided into two distinct stages: a first aging process that grows the oxide layer, followed by a second aging process that stabilizes the structure without significant electrolyte loss. This segmentation allows each stage to be optimized independently, achieving high oxide layer quality while minimizing the need for re-impregnation and reducing overall process complexity
3Volume of stationary object
If capacitor volume is minimized for high energy density, then fewer anodes can be used, but this reduces capacitance and energy storage capacity
Solution Approach 1:
Multiple anodes are nested within a compact stack configuration, with each anode surrounded by cathode and separator layers in a space-efficient arrangement. This nested structure maximizes the number of anodes that can fit within the minimal capacitor volume, thereby achieving both high energy density and sufficient capacitance for ICD applications
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method extends the maintenance cycle of aluminum electrolytic capacitors to up to 5 years in storage and 2 years post-implantation, significantly increasing the battery life of implantable cardioverter defibrillators by minimizing deformation and leakage current.
Implementation Method 1
impregnating an aluminum electrolytic capacitor with a first electrolyte to form a first impregnated capacitor
Implementation Method 2
aging the first impregnated capacitor using a first aging process to form a first aged capacitor
Implementation Method 3
aging the first impregnated capacitor using a first aging process
Data Source
AI summary
A method of manufacturing an aluminum electrolytic capacitor includes impregnating an aluminum electrolytic capacitor with a first electrolyte to form a first impregnated capacitor, aging the first impregnated capacitor using a first aging process to form a first aged capacitor, impregnating the first aged capacitor with a second electrolyte to form a second impregnated capacitor, the second electrolyte being different from the first electrolyte, aging the second impregnated capacitor using a final aging process to form a final aged capacitor, and impregnating the final aged capacitor with a third electrolyte.