Solid Electrolytic Capacitor With Conductive Polymer for Low Leakage
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Solution Overview
Problem
Conventional solid electrolytic capacitors using in situ polymerized intrinsically conductive polymers suffer from high leakage current and failure at high voltages, with performance being humidity-dependent, especially under dry conditions.
Innovation Solution
A capacitor assembly is designed with a solid electrolyte containing intrinsically conductive polymers with specific repeating units, maintaining low leakage current even under dry conditions by ensuring negatively charged anions remain dissociated, creating a barrier at the cathode-dielectric boundary, and is housed in a dry atmosphere with relative humidity of 10% or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If in situ polymerized intrinsically conductive polymers are used as solid electrolyte, then low ESR and non-burning failure mode are achieved, but high leakage current and failure at high voltages occur
Solution Approach 1:
The patent modifies the chemical structure of the intrinsically conductive polymer by introducing specific repeating units with ether linkages and adjustable alkyl chains (formula I). This structural parameter change optimizes the polymer's electrical properties, achieving low ESR while maintaining low leakage current through controlled molecular architecture rather than changing the polymerization method itself.
Solution Approach 2:
The patent creates a composite solid electrolyte system by combining intrinsically conductive polymer chains with specific counterions (cations and anions) and dopants. This composite approach allows the polymer matrix to provide low ESR while the ionic components contribute to stable electrical performance and reduced leakage current, particularly under dry conditions.
2Reliability
If PEDOT:PSS dispersions are used as solid electrolyte, then lower leakage current is achieved, but DCL decay rate becomes highly dependent on humidity levels
Solution Approach 1:
The patent introduces hydrophobic ether linkages and alkyl chains into the polymer structure at specific locations along the polymer chain. This local modification creates regions with controlled hydrophobicity that reduce moisture sensitivity locally, allowing the electrolyte to maintain stable DCL characteristics across varying humidity environments without requiring uniform structural changes throughout the entire polymer.
Solution Approach 2:
The patent creates an inherently moisture-resistant environment within the polymer electrolyte structure by incorporating hydrophobic ether groups and alkyl chains. These structural features effectively create a water-repellent microenvironment that protects the conductive polymer from humidity-induced degradation, enabling stable performance in both dry and humid conditions without external protective measures.
3Loss of energy
If conventional intrinsically conductive polymers are used, then low ESR is achieved, but failure occurs at high voltages during fast switch on or current spike
Solution Approach 1:
The patent adjusts the electrical and mechanical parameters of the intrinsically conductive polymer by incorporating repeating units with adjustable alkyl chain lengths (a=0-10, b=1-18). This parameter optimization enhances the polymer's charge carrier mobility and structural stability, enabling it to withstand high voltage stress during fast switch-on and current spike conditions while maintaining low ESR through controlled molecular weight and chain architecture.
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 assembly exhibits significantly reduced leakage current over time, maintaining low values even under dry conditions, ensuring stable performance across varying humidity levels and extreme conditions like high temperatures and voltages.
Implementation Method 1
the solid electrolyte includes an intrinsically conductive polymer containing repeating units having the following formula (I)... ensuring negatively charged anions remain dissociated, creating a barrier at the cathode-dielectric boundary
Implementation Method 2
an anode that contains a dielectric formed on a sintered porous body
Data Source
AI summary
A capacitor assembly that is capable of exhibiting good properties under dry conditions. The ability to perform under such conditions is due in part to the use of an intrinsically conductive polymer in the solid electrolyte that contains repeating units having the following formula (I):wherein,R is (CH2)a—O—(CH2)b;a is from 0 to 10;b is from 1 to 18;Z is an anion; andX is a cation.