Solid Electrolytic Capacitor with Nickel Oxide Cathode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solid electrolytic capacitors face challenges in achieving low equivalent series resistance (ESR) and high capacitance while maintaining mechanical strength and cost-effectiveness, particularly in high-frequency applications, due to limitations in surface area enhancement and material bonding.
Innovation Solution
The use of an anode foil with a rough surface layer made of aluminum and a dielectric oxide layer, combined with a cathode foil featuring a nickel layer made of nickel and nickel oxide, enhances the surface area and bonding strength, leading to increased capacitance and reduced ESR, while maintaining mechanical integrity and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-valve metal foil (nickel foil) is used as cathode foil to increase capacitance, then the electrostatic capacitance at cathode foil increases to substantially infinite value, but the effective contact area between cathode foil and solid electrolyte cannot be increased because non-valve metal foil cannot be roughened by etching process
Solution Approach 1:
The invention uses a composite structure for the cathode foil consisting of a non-valve metal base foil (nickel, copper, or bronze) combined with a separate nickel oxide layer formed by anodizing. This composite approach allows the base foil to provide high capacitance while the oxide layer provides the roughened surface for increased effective contact area with the solid electrolyte, resolving the contradiction between capacitance and contact area.
2Area of moving object
If nickel plated layer is formed on roughened aluminum foil surface by non-electrolytic plating method, then the surface area is increased, but the nickel plated layer cannot be formed uniformly inside pores and the aluminum foil cannot be bonded to nickel plated layer securely
Solution Approach 1:
The invention replaces the non-electrolytic plating method with an anodizing process that uses electrochemical oxidation instead of mechanical or chemical plating. This substitution allows for uniform formation of nickel oxide layer inside the pores of the roughened aluminum foil surface and creates strong bonding through oxide integration, resolving the issues of non-uniform coating and weak bonding.
3Ease of manufacture
If aluminum foil is used as cathode foil to reduce cost, then material cost is reduced, but the surface cannot be roughened effectively and bonding to solid electrolyte is weak
Solution Approach 1:
The invention applies preliminary anodizing treatment to the aluminum foil cathode before assembly, which pre-forms the roughened oxide surface structure. This preliminary action ensures that when the solid electrolyte is applied, it bonds strongly to the pre-prepared rough surface, achieving both cost-effectiveness of aluminum and strong bonding performance.
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 configuration results in a solid electrolytic capacitor with significantly improved capacitance and reduced ESR, offering excellent performance and reliability at a lower cost, suitable for high-frequency applications in electronic devices.
Implementation Method 1
The surface of the aluminum foil can be roughened by an etching process
Implementation Method 2
a dielectric oxide layer provided on a rough surface layer
Implementation Method 3
a nickel layer made of nickel and nickel oxide
Data Source
AI summary
A solid electrolytic capacitor includes an anode foil, a solid electrolyte provided on the anode foil and made of conductive polymer, and a cathode foil provided on the solid electrolyte and facing the anode foil across the solid electrolyte. The anode foil includes an anode base made of aluminum, a rough surface layer made of aluminum and provided on a surface of the anode base, and a dielectric oxide layer provided on the rough surface layer and contacting the solid electrolyte. The cathode foil includes a cathode base made of aluminum, and a nickel layer provided on a surface of the cathode base and contacting the solid electrolyte. The nickel layer faces the dielectric oxide layer of the anode foil across the solid electrolyte. The nickel layer is made of nickel and nickel oxide. This solid electrolytic capacitor has a large capacitance and a low equivalent series resistance while being inexpensive and highly reliable.