Electrolytic Capacitor Intermediate Electrolyte High Voltage
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Solution Overview
Problem
Hybrid polymer capacitors using γ-butyrolactone and sulfolane solvents are limited to working voltages of no more than 120 V due to their limited oxidizing capability and pose environmental and safety hazards, while also potentially damaging polymer layers like PEDOT:PSS.
Innovation Solution
Incorporating an intermediate electrolyte between the polymer layer and the working electrolyte, which can be a conductive, viscous material, allows for the use of more aggressive working electrolyte materials, enabling capacitors to operate at higher voltages up to 450 V without damaging the polymer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If γ-butyrolactone and sulfolane solvents are used as working electrolyte, then the capacitor can operate at higher voltages, but the polymer layer is damaged and the solvents pose environmental and safety hazards
Solution Approach 1:
A water-soluble polymer coating is applied to the anode foil surface as an intermediary layer between the high-voltage working electrolyte (containing γ-butyrolactone and/or sulfolane) and the aluminum oxide dielectric. This coating prevents direct contact between the working electrolyte and the polymer layer, avoiding damage while enabling high-voltage operation. The coating acts as a protective mediator that allows the beneficial high-voltage properties of GBL/sulfolane to be utilized without their harmful effects on the polymer layer.
2Temperature
If aggressive working electrolyte materials are used to enable higher voltages, then the working voltage increases, but the polymer layer is damaged or degraded
Solution Approach 1:
The water-soluble polymer coating serves as a protective intermediary that shields the polymer layer from aggressive working electrolyte materials. This allows the use of high-oxidizing-capability electrolytes like GBL and sulfolane that can support voltages above 120 V without directly degrading the polymer layer, thus maintaining both high voltage capability and polymer layer reliability.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte system by introducing a water-soluble polymer coating with specific protective properties. This parameter change allows the working electrolyte to have high oxidizing capability for high-voltage operation while the coating parameter provides protection to the polymer layer, resolving the contradiction between voltage capability and polymer stability.
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 intermediate electrolyte protects the polymer layer from the working electrolyte, enabling capacitors to withstand higher voltages and maintain low equivalent serial resistance (ESR) values, even at low temperatures, while using less harmful chemicals and extending the capacitor's lifetime.
Implementation Method 1
The intermediate electrolyte may prevent that too much of the working electrolyte gets in contact with the polymer layer, thereby the intermediate electrolyte may prevent the working electrolyte from damaging, degrading or swelling the polymer layer.
Implementation Method 2
The intermediate electrolyte may be different from the working electrolyte with respect to its composition... the intermediate electrolyte being free from ethylene glycol may ensure that the polymer is not damaged by ethylene glycol.
Implementation Method 3
The working electrolyte may also be a conductive, viscous material. A voltage may be applied to the working electrolyte via the cathode foil. The working electrolyte may act as a second electrode of the capacitor.
Implementation Method 4
The cathode foil can be oxidized. Accordingly, the cathode foil may have an artificially formed oxide layer. The oxide layer may be thicker than a natural oxide having a thickness of 2 nm to 3 nm.
Implementation Method 5
The intermediate electrolyte may comprise polyol and a conducting salt. The conducting salt may ensure that the intermediate electrolyte is conductive.
Implementation Method 6
The polyol can be glycerol, sugar alcohol and polyvinyl alcohol... These material can ensure that the intermediate electrolyte is stable enough with the polymer layer and at the same time enable an oxidization of the polymer layer.
Data Source
AI summary
An electrolytic capacitor is disclosed. In an embodiment an electrolytic capacitor includes an anode foil, a cathode foil, a working electrolyte arranged between the anode foil and the cathode foil, a polymer layer arranged on the anode foil, wherein the polymer layer comprises PEDOT:PSS and an intermediate electrolyte arranged between the polymer layer and the working electrolyte, wherein the intermediate electrolyte is different from the working electrolyte with respect to its composition.