Electrolytic Capacitor Anode Pore Segmentation for Low ESR
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Solution Overview
Problem
Existing electrolytic capacitors face challenges in achieving both high capacitance and low equivalent series resistance (ESR) due to issues with pore distribution and conductive path formation in the anode body, as previous methods either increase pore diameter or fail to form effective conductive paths.
Innovation Solution
The electrolytic capacitor design includes an anode body with distinct regions of sintered first and second particles, having different average diameters, resulting in a pore diameter distribution with peaks at less than and greater than 0.5 μm, which enhances specific surface area and conductive path formation, respectively, thereby improving capacitance and reducing ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pore diameter in the anode body is increased to improve current collection and reduce ESR, then the equivalent series resistance decreases, but the specific surface area decreases leading to lower capacitance
Solution Approach 1:
The anode body is divided into two distinct regions with different pore diameter characteristics: a first region with smaller pores (peak ≤0.5 μm) that provide high specific surface area for capacitance, and a second region with larger pores (peak >0.5 μm) that provide good current collection and low ESR. This segmentation allows both contradictory requirements to be satisfied in different parts of the same component.
Solution Approach 2:
Different regions of the anode body are given different local pore structure qualities: the first region has a pore diameter distribution optimized for surface area (smaller pores), while the second region has a pore diameter distribution optimized for conductivity (larger pores). This local differentiation resolves the contradiction by allowing each region to specialize in one function.
2Area of stationary object
If only small particles are used to increase specific surface area, then capacitance improves, but conductive path formation is insufficient leading to higher ESR
Solution Approach 1:
Instead of using a uniform particle size, the invention segments the particle population into two groups: small particles (average diameter ≤0.5 μm) for the first region that provide high surface area, and large particles (average diameter >0.5 μm) for the second region that facilitate conductive path formation. This resolves the contradiction between surface area and conductivity.
Solution Approach 2:
The small particles are concentrated in the first region where they provide the necessary specific surface area for capacitance, while large particles are concentrated in the second region where they provide the necessary conductive pathways. Each particle size is locally optimized for its specific function.
3Loss of energy
If only large particles are used to improve conductive path formation, then ESR decreases, but the specific surface area decreases leading to lower capacitance
Solution Approach 1:
The particle population is segmented into two distinct groups with different size ranges, with small particles assigned to the first region for surface area and large particles assigned to the second region for conductivity. This segmentation allows both functions to be optimized simultaneously without compromise.
Solution Approach 2:
The anode body is given different local particle size qualities: the first region contains predominantly small particles optimized for surface area, while the second region contains predominantly large particles optimized for conductivity. This local differentiation resolves the contradiction.
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 achieves a balance of high electrostatic capacity and low ESR by optimizing the pore structure, allowing for efficient current collection and reduced bulk resistance.
Implementation Method 1
The anode body is formed by sintering a molded body of metal particles
Implementation Method 2
a dielectric layer formed on the surface of the anode body
Data Source
AI summary
An electrolytic capacitor includes an anode body having a porous structure, an anode lead partially embedded in the anode body, a dielectric layer formed on a surface of the anode body, and a cathode part that covers at least part of the dielectric layer. The anode body has a first region in which first particles sintered together and a second region in which second particles sintered together. The average particle diameter D1 of the first particles is smaller than the average particle diameter D2 of the second particles. The volume-based pore diameter distribution of the anode body with the dielectric layer has a first peak in a range of less than or equal to 0.5 μm in pore diameter, and a second peak in a range of more than 0.5 μm in pore diameter.