Solid Electrolytic Capacitor Cation Ratio ESR Stability
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Solution Overview
Problem
Solid electrolytic capacitors experience an increase in Equivalent Series Resistance (ESR) due to dedoping reactions, especially under heat stress, which affects their performance and reliability.
Innovation Solution
A solid electrolytic capacitor design with a controlled molecular ratio of cation components relative to 1 mol of functional groups in the electrolyte layer, where the cation component ratio is limited to 6 or less, helps suppress dedoping reactions and maintain low ESR even under heat stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excessive acid component is added to suppress dedoping reaction, then initial ESR is reduced, but heat stability deteriorates under high temperature stress
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by specifying precise molecular ratios of cationic components (0.5-2.0 relative to dopant functional groups) and controlling anionic component content (1.0-5.0 relative to dopant functional groups). This parameter optimization resolves the contradiction by achieving both low initial ESR and high heat stability through balanced ionic composition rather than excessive acid addition.
Solution Approach 2:
The patent employs a composite electrolytic solution system combining multiple cationic components (such as lithium salts, sodium salts, potassium salts) with anionic components and solvents. This composite approach allows synergistic effects where different ions work together to suppress dedoping reactions while maintaining stability under heat stress, overcoming the limitations of single-component systems.
2Productivity
If solid electrolyte layer is formed to reduce size and ESR, then capacity density increases, but leakage current repair function is lost
Solution Approach 1:
The patent merges the advantages of both solid electrolyte and liquid electrolyte systems by forming a solid electrolyte layer on the capacitor element and then impregnating it with liquid electrolytic solution. This hybrid structure combines the low ESR and small size benefits of solid electrolytes with the leakage repair capability of liquid electrolytes, resolving the contradiction between capacity density and reliability.
Solution Approach 2:
The patent applies different electrolyte properties to different regions: the solid electrolyte layer provides low ESR and compact structure where needed, while the impregnated liquid electrolytic solution provides leakage repair function in the porous structure. This local differentiation of electrolyte states optimizes both capacity density and reliability simultaneously.
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
This design effectively stabilizes the ESR of the solid electrolytic capacitor, ensuring high heat stability and maintaining excellent conductivity after exposure to heat stress.
Implementation Method 1
the conductivity thereof gets worse by the dedoping reaction of the dopants and the Equivalent Series Resistance (ESR) of the solid electrolytic capacitor increases
Implementation Method 2
the dedoping reaction can be suppressed by the excessive acids in the molecular ratio of the acid component and the base component that are the solute component of the electrolytic solution. This report assumes that the dedoping reaction is suppressed because the equilibrium of the dopant that is the acid component and the acid component in the electrolytic solution is maintained
Implementation Method 3
a solid electrolyte layer including a dopant and a conjugated polymer
Implementation Method 4
conductive polymers which are derived from monomers having n conjugated double bonds, such as poly(3,4-ethylenedioxythiophene) which has excellent adhesion to the dielectric oxide film
Data Source
AI summary
In a solid electrolytic capacitor having an electrolyte layer consisting of a solid electrolyte layer and a liquid, the solid electrolytic capacitor, which suppresses a dedoping reaction and which ESR thereof does not keenly increase, in particular, after a loading of heat stress, is provided. In the solid electrolytic capacitor, the electrolyte layer is formed in the capacitor element which is formed by opposing an anode foil and a cathode foil. This electrolyte layer includes the solid electrolyte layer and the liquid. The solid electrolyte layer includes a conductive polymer consisting of a dopant and a conjugated polymer. The liquid is filled in air gaps in the capacitor element on which the solid electrolyte layer is formed. A molecular ratio of a cation component relative to 1 mol of a functional group which can contribute to a doping reaction of the dopant, in the electrolyte layer is 6 or less.