Separator-Less Ultracapacitor Electrolyte for Wide-Temperature Operation
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Solution Overview
Problem
Existing energy storage cells, particularly ultracapacitors, suffer from performance degradation at elevated temperatures due to electrolyte degradation and the need for separators that introduce undesirable characteristics, limiting their operating range to below about 200°C, and there is a need for improved performance and a wider range in extreme conditions.
Innovation Solution
The ultracapacitor employs a combination of carbon-based electrodes, a polymer electrolyte, and a hermetic seal to maintain performance over a wide temperature range without a separator, using additives like gelling agents and ceramic powders to stabilize the electrolyte, and a pressurized housing to maintain integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolytes are used in ultracapacitors, then the device can operate at standard temperatures, but the electrolyte degrades at elevated temperatures above 200°C, limiting the operating temperature range
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using ionic liquids with specific cations (imidazolium, pyridinium, pyrrolidinium, phosphonium, ammonium) and anions (BF4-, PF6-, CF3SO3-, CF3COO-). This compositional parameter change enables the electrolyte to maintain stability across an extended temperature range from -40°C to 200°C, resolving the contradiction between temperature range and electrolyte stability.
Solution Approach 2:
The patent employs composite electrolyte systems combining ionic liquids with conventional organic electrolytes or water. This composite approach leverages the thermal stability of ionic liquids while maintaining the beneficial electrochemical properties of conventional electrolytes, achieving both broad temperature operation and reliable performance.
2Reliability
If a separator is used to prevent contact between electrodes, then short circuits are prevented, but the separator introduces contamination and decomposition that degrade performance at elevated temperatures
Solution Approach 1:
The patent removes the separator component entirely from the ultracapacitor structure. Instead of using a separator to prevent electrode contact, the design relies on the inherent stability and properties of the ionic liquid electrolyte and electrode configuration to prevent short circuits, thereby eliminating the harmful contamination and decomposition effects that separators introduce at elevated temperatures.
Solution Approach 2:
The ionic liquid electrolyte itself acts as the intermediary medium that prevents direct contact between electrodes while maintaining ionic conductivity. The electrolyte's unique properties allow it to function both as the charge transport medium and as a protective barrier, replacing the traditional separator's function without its drawbacks.
3Strength
If metallic canisters are used to provide physical protection, then robust mechanical strength is achieved, but the canister reacts with the energy storage cell at elevated temperatures, causing degradation
Solution Approach 1:
The patent creates a chemically inert environment by using ionic liquids as the electrolyte medium. These ionic liquids are highly stable and non-reactive, even at elevated temperatures up to 200°C, preventing chemical reactions between the canister and the energy storage cell components. This inert environment allows the use of conventional metallic canisters without the reaction problems that occur with traditional electrolytes.
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 combination of materials and construction ensures robust operation across a wide temperature range from -110°C to 275°C, with improved performance and durability.
Implementation Method 1
a polymer electrolyte, and a hermetic seal to maintain performance over a wide temperature range without a separator, using additives like gelling agents and ceramic powders to stabilize the electrolyte
Implementation Method 2
a hermetic seal to maintain performance over a wide temperature range
Implementation Method 3
a pressurized housing to maintain integrity
Implementation Method 4
The ultracapacitor employs a combination of carbon-based electrodes
Data Source
Figure 1A
Figure 1B
Figure 2~5
AI summary
Electric double layer capacitor devices are disclosed. The devices may be suitable for operation of wide temperature ranges. In some cases, the capacitor features a solid state electrolyte that includes an ionic liquid doped polymer matrix.