Solid Electrolytic Capacitor with In Situ Polymerized Conductive Polymer
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Solution Overview
Problem
Solid electrolytic capacitors with polymer slurry-based electrolytes face significant capacitance drop at low temperatures, limiting their use in cold environments such as aerospace and military applications.
Innovation Solution
A solid electrolytic capacitor design featuring a sintered porous anode, a dielectric layer, and a solid electrolyte composed of in situ polymerized conductive polymer and hydroxy-functional nonionic polymer, which maintains stability and high capacitance across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer slurry-based electrolyte is used, then low ESR and non-burning failure mode are achieved, but capacitance drops significantly at low temperatures
Solution Approach 1:
The patent combines polymer slurry-based electrolyte with hydroxy-functional nonionic polymer to create a composite electrolyte system. This composite structure allows the capacitor to maintain the low ESR and non-burning failure mode advantages of polymer slurries while adding temperature stability through the hydroxy-functional polymer component that prevents significant capacitance drop at low temperatures.
2Ease of manufacture
If conventional solid electrolyte is used, then manufacturing simplicity is maintained, but capacitance is highly temperature dependent
Solution Approach 1:
The invention creates a composite solid electrolyte combining conventional polymer slurry with hydroxy-functional nonionic polymer. This composite approach maintains the ease of manufacturing through standard electrolyte application processes while significantly improving capacitance stability across temperature ranges by leveraging the temperature-stabilizing properties of the hydroxy-functional polymer.
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 capacitor exhibits stable capacitance and low equivalent series resistance at temperatures as low as -55°C, with minimal capacitance loss and fluctuation, enabling reliable performance in varying conditions.
Implementation Method 1
anodically oxidizing a sintered porous anode to form a dielectric layer that overlies the anode
Implementation Method 2
chemically polymerizing a monomer in situ to form a conductive polymer
Data Source
AI summary
A capacitor whose electrical properties can be stable under a variety of different conditions is provided. The solid electrolyte of the capacitor is formed from a combination of an in situ polymerized conductive polymer and a hydroxy-functional nonionic polymer. One benefit of such an in situ polymerized conductive polymer is that it does not require the use of polymeric counterions (e.g., polystyrenesulfonic anion) to compensate for charge, as with conventional particle dispersions, which tend to result in ionic polarization and instable electrical properties, particularly at the low temperatures noted above. Further, it is believed that hydroxy-functional nonionic polymers can improve the degree of contact between the polymer and the surface of the internal dielectric, which unexpectedly increases the capacitance performance and reduces ESR.