Electric Double-Layer Capacitor Electrolyte Concentration Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electric double-layer capacitors face challenges with capacity decrease and increased resistance during high-current cycles, particularly in large-scale applications like hybrid vehicles and UPSs, due to limitations in electrolyte solutions such as propylene carbonate and acetonitrile, which suffer from high resistivity, low energy density, and safety concerns.
Innovation Solution
An electric double-layer capacitor with an electrolyte concentration adjusted to 1.25 to 2.5 mol/L, using a combination of ionic liquids and carbonate-based solvents with high dielectric constants, such as ethylene carbonate, to enhance electrochemical stability and conductivity, thereby improving cycle and high-current charge/discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If propylene carbonate is used as electrolyte solvent, then safety and non-toxicity are improved, but resistivity increases and high-output performance deteriorates
Solution Approach 1:
The patent combines propylene carbonate (safe but high resistivity) with acetonitrile (low resistivity but unsafe) in a mixed solvent system. This merging allows the electrolyte to achieve both safety and low resistivity, resolving the contradiction between safety and high-output performance.
Solution Approach 2:
The patent creates a composite electrolyte system by combining multiple solvents (propylene carbonate and acetonitrile) with specific additives. This composite approach enables the electrolyte to exhibit properties that neither component alone can achieve, specifically maintaining safety while reducing resistivity for high-output applications.
2Productivity
If acetonitrile is used as electrolyte solvent, then viscosity decreases and solubility increases, but boiling point decreases and safety deteriorates
Solution Approach 1:
The patent merges acetonitrile (high productivity but unsafe) with propylene carbonate (safe but lower productivity) in controlled proportions. This combination allows the electrolyte to maintain good charge/discharge rates while achieving safety requirements for large-scale applications.
Solution Approach 2:
The patent optimizes the concentration ratios of acetonitrile and propylene carbonate, along with adding specific additives, to change the physical parameters of the electrolyte. This parameter optimization achieves the right balance between viscosity/solubility (productivity) and boiling point/safety.
3Quantity of substance
If electrolyte concentration is increased to improve capacity, then capacity increases, but resistance increases and cycle characteristics deteriorate
Solution Approach 1:
The patent optimizes electrolyte concentration within a specific range (1.25 to 2.5 mol/L) rather than simply maximizing it. This parameter optimization, combined with the mixed solvent system, achieves high capacity while maintaining low resistance and good cycle characteristics.
Solution Approach 2:
The patent uses a composite electrolyte formulation with multiple solvents and additives that work synergistically. This composite approach allows the system to achieve high ion conductivity and capacity at optimized concentrations without the resistance increase and cycle deterioration that would occur with simple high-concentration 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 solution significantly reduces capacity decrease and resistance increase, enabling the electric double-layer capacitor to maintain high performance over extended cycles, making it suitable for large-scale power applications like hybrid vehicles and UPSs.
Implementation Method 1
an electric double-layer is a structure wherein a thin film layer of an object exhibits continuous presence of positive charges at one side and continuous presence of negative charges at the other side
Implementation Method 2
based on the principle of adsorption/desorption of charges onto the electric double-layers at the interfaces between solid electrodes and solid or liquid electrolytes
Implementation Method 3
dissociation of solid surface molecules, arrangement/adsorption of dipoles toward the interface
Implementation Method 4
capability to dissolve ionic conductive salts at high concentrations
Data Source
AI summary
Provided is an electric double-layer capacitor. The electric double-layer capacitor includes an electrode portion composed of an anode and a cathode; a separator for providing electrical isolation between the anode and cathode; and an electrolyte solution which is filled in a space between the anode and cathode so as to form electric double-layers on surfaces of the anode and cathode upon application of a predetermined voltage, and in which a solvent and a solute are mixed so as to have a concentration of 1.25 to 2.5 mol/L.