Anode Foil Oxide Reformation for Low-Deformation Capacitors
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Solution Overview
Problem
Existing oxide formation processes for electrolytic capacitors, particularly in implantable cardioverter defibrillators, negatively affect capacitance and deformation due to multiple depolarization steps.
Innovation Solution
A method involving controlled oxide layer formation and reformation on an anodic foil, including specific voltage and current targets, followed by heating to induce defects, to maximize the boehmite phase and minimize pseudo-boehmite phase, thereby reducing deformation and maintaining low leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple depolarization steps are used in oxide formation process, then oxide layer is formed on anode foil, but capacitance decreases and deformation increases
Solution Approach 1:
The patent changes the parameters of oxide formation by using a single depolarization step at controlled voltage and current targets, followed by specific heating treatment. This modifies the electrochemical parameters to maximize boehmite phase while minimizing pseudo-boehmite phase, thereby maintaining capacitance and reducing deformation without requiring multiple depolarization cycles
Solution Approach 2:
The patent utilizes phase transition during heating treatment to transform the oxide layer structure. By heating to specific temperature ranges, the pseudo-boehmite phase converts to boehmite phase, achieving the desired oxide layer quality with reduced deformation and maintained capacitance from a single depolarization step
2Reliability
If multiple depolarization steps are used in oxide formation process, then oxide layer is formed on anode foil, but deformation increases
Solution Approach 1:
The patent controls the electrochemical parameters during a single depolarization step and subsequent heating treatment to minimize pseudo-boehmite phase formation. By optimizing voltage targets, current targets, and heating temperature, the oxide layer achieves desired quality with minimal deformation, eliminating the need for multiple depolarization steps that would increase deformation
Solution Approach 2:
The heating treatment induces phase transition that converts unstable pseudo-boehmite phase to stable boehmite phase. This phase transformation occurs during controlled heating, resulting in an oxide layer with minimal deformation and high stability, achieved through a single depolarization step followed by heating rather than multiple depolarization cycles
3Reliability
If heating is applied to induce defects in oxide layer, then boehmite phase is maximized, but energy consumption increases
Solution Approach 1:
The patent optimizes heating parameters including temperature range and duration to achieve phase transition from pseudo-boehmite to boehmite phase. By controlling these parameters, the process maximizes boehmite phase formation with minimal energy input, balancing oxide layer quality improvement against energy consumption
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 enhances capacitor performance by reducing deformation and maintaining low leakage current, improving energy density and reliability.
Implementation Method 1
maintaining a target current between the immersed anodic foil and the electrolyte solution until a target voltage is reached to form an oxide layer
Implementation Method 2
heating the anodic foil to induce defects in the reformed oxide layer
Data Source
AI summary
A method of producing a capacitor electrode includes forming an oxide layer on a foil. The method also includes heating the foil to a target temperature so as to induce defects in the oxide layer. The target temperature is about 450° C. to 560° C. and the duration of heating the foil to the target temperature is less than 4 minutes. The oxide layer is reformed so as to generate a reformed oxide layer that is an aluminum oxide with a boehmite phase and a pseudo-boehmite phase.