Hybrid Capacitor Polymer Coating with Washed PSSA for Lower ESR
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Solution Overview
Problem
Existing hybrid capacitors face issues with stability and increased equivalent series resistance (ESR) due to the use of excessive polystyrenesulfonic acid (PSSA) as a dopant, which can lead to corrosion and leakage current, especially in high humidity environments.
Innovation Solution
A method involving a conductive polymer dispersion with a molar excess of anionic counterions, such as PSSA, is used to form a homogenized dispersion, which is applied to a metal oxide layer, cured to form a conductive polymer layer with a neutral or positive surface charge, minimizing the presence of non-conducting anionic counterions on the surface, thereby enhancing polymer/substrate binding and reducing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If excessive PSSA is used as dopant to stabilize conductive polymer nanoparticles in dispersion, then the polymer particles remain stable in dispersing agent, but the conductivity of the final polymer film decreases and corrosion/leakage current increases
Solution Approach 1:
The patent extracts and removes the harmful excessive PSSA from the final capacitor structure through a two-stage process: first incorporating PSSA during polymerization to stabilize nanoparticles, then removing excess PSSA through washing/centrifugation steps before applying the dispersion to the capacitor. This leaves only the necessary amount of PSSA bound to the polymer chains, eliminating the corrosion and leakage problems while maintaining nanoparticle stability.
Solution Approach 2:
The patent changes the concentration parameter of PSSA from excessive amounts to a controlled stoichiometric amount during polymerization. By precisely controlling the PSSA:monomer ratio and removing excess PSSA through washing steps, the system transforms from having harmful high concentrations to having optimal controlled concentrations, improving both stability and reliability.
2Stability of the object's composition
If excessive PSSA is used to achieve negative Z-potential on particle surface, then nano particles remain stable in dispersing agent, but equivalent series resistance (ESR) increases and capacitance stability decreases
Solution Approach 1:
The patent removes excess PSSA that causes high ESR and poor capacitance stability through washing and centrifugation steps. Only the necessary PSSA bound to polymer chains remains, eliminating the harmful effects on ESR and capacitance stability while preserving the colloidal stability provided by the bound PSSA.
Solution Approach 2:
The patent uses excessive PSSA temporarily during polymerization to ensure complete stabilization of all polymer nanoparticles, then removes the excess through washing steps. This partial excessive action ensures all particles are stabilized while eliminating the harmful effects of excess PSSA on ESR and capacitance stability.
3Reliability
If PSSA is used as dopant and anionic counter ion, then conductive polymer chains are formed, but the acid leads to corrosion of metal and capacitor failure in high humidity environment
Solution Approach 1:
The patent extracts and removes the harmful excessive PSSA through washing and centrifugation steps before applying the dispersion to the capacitor. This eliminates the free acid that causes corrosion in humid environments, while retaining the necessary PSSA bound to polymer chains for conductivity.
Solution Approach 2:
The patent converts the harmful effect of PSSA by controlling its quantity and binding state. PSSA bound to polymer chains provides necessary conductivity, while excess free PSSA that causes corrosion is removed. The same substance becomes beneficial when properly controlled and harmful when excessive.
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 results in improved capacitance stability and lower ESR, with enhanced conductivity and resistance to corrosion, as demonstrated by SEM EDS and conductivity studies, showing a higher sulfur content and more positive surface charge, indicating better electrical characteristics.
Implementation Method 1
curing the monomer to form a coated film
Data Source
AI summary
An improved dispersion, which is particularly suitable for use in forming a hybrid capacitor, and improved method for forming a hybrid capacitor, and an improved capacitor is provided. The method comprises forming a dispersion comprising a conductive polymer, a dispersing agent, a monomer of the conductive polymer and a molar excess of anionic counterion per mole of conductive polymer and monomer. The dispersion is homogenized to form a homogenized dispersion. A capacitor is formed comprising a conductive layer formed from the homogenized dispersion.