Electrolytic Capacitor Phosphorus Coating ESR Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid electrolytic capacitors with conductive polymers and liquid components face increased equivalent series resistance (ESR) due to reactive interactions between the liquid component and the inorganic conductive layer, leading to degradation and capacitance loss, especially when the liquid component infiltrates the cathode foil's pores.
Innovation Solution
A phosphorus-containing coating layer is applied to the inner walls of the cathode body's pores, providing solvent resistance and preventing direct contact between the liquid component and the metal, while an inorganic conductive layer is formed on the outer surface to reduce ESR and maintain capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic conductive layer is formed on the cathode body to reduce ESR, then electrical conductivity is improved, but the liquid component infiltrates the pores and causes reactive interactions leading to degradation
Solution Approach 1:
A phosphorus-containing compound layer is introduced as an intermediary between the cathode body and the liquid component. This intermediate layer prevents direct contact and reactive interactions between the liquid component and the cathode structure, thereby preventing degradation while allowing the inorganic conductive layer to maintain low ESR
Solution Approach 2:
The cathode body is constructed as a composite structure with multiple layers: the cathode body itself, an inorganic conductive layer for electrical conductivity, and a phosphorus-containing compound layer for protection. This composite structure combines the beneficial properties of each layer while mitigating their individual drawbacks
2Reliability
If the cathode body uses a roughened surface with pores to increase surface area, then capacitance is improved, but the liquid component can penetrate into the pores causing hydration reactions and degradation
Solution Approach 1:
The phosphorus-containing compound layer is selectively applied to line the inner walls of the pores in the cathode body. This local treatment provides protection exactly where the liquid component would cause harm (inside the pores) while maintaining the high surface area structure needed for high capacitance
Solution Approach 2:
The phosphorus-containing compound acts as a protective intermediary within the pore structure, preventing direct interaction between the liquid component and the cathode body material, thereby preventing hydration reactions while allowing the porous structure to maintain its capacitance-enhancing geometry
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 phosphorus coating layer effectively suppresses degradation and hydration reactions, maintaining low ESR and capacitance even in high-humidity environments, and the inorganic conductive layer ensures electrical connectivity, reducing resistance and preserving capacitance over time.
Implementation Method 1
a phosphorus-containing compound layer is attached to at least a part of inner wall of the pore in the cathode body
Implementation Method 2
an inorganic conductive layer covering at least a part of the outer surface
Data Source
AI summary
An electrolytic capacitor includes an anode body including a dielectric layer, a cathode body, and a conductive polymer layer and a liquid component that are disposed between the anode body and the cathode body. The cathode body includes a base material part having an outer surface that is roughened surface and has a pore opened at the outer surface, and an inorganic conductive layer covering at least a part of the outer surface. The base material part includes a first coating layer disposed along at least a part of inner wall of the pore. The first coating layer contains phosphorus.