Organic Electrolyte Supercapacitor for Ultra-Low Temperature Conductivity
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Solution Overview
Problem
Existing supercapacitors face issues with electrolyte solidification at low temperatures, leading to poor compatibility between electrolyte and electrode materials, which affects conductivity and performance in extreme cold conditions.
Innovation Solution
A supercapacitor design incorporating a compound represented by structural formula 1 as an additive in the organic electrolyte solution, combined with specific surface area ratios and mass percentages of porous carbon materials, enhances compatibility and conductivity by optimizing the interaction between electrolyte and electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolyte is used in AN system, then working voltage window can be expanded to 3.0V and working temperature range is -40°C to 65°C, but at temperatures below -40°C the electrolyte solidifies, ion transport channel is blocked, conductivity becomes extremely low, and compatibility with electrode materials deteriorates
Solution Approach 1:
The patent modifies the electrolyte composition by introducing a new solvent system based on cyclic carbonate esters with specific molecular structures (formula I and II). This changes the physical and chemical parameters of the electrolyte, including its freezing point, viscosity, and solvation properties, enabling it to remain liquid and conductive at temperatures below -40°C while maintaining stability with carbon electrode materials.
Solution Approach 2:
The patent creates a composite electrolyte system by combining cyclic carbonate ester solvents (formula I and II) with lithium salts. This composite approach leverages the low-temperature fluidity of the cyclic carbonate esters and the ionic conductivity of the lithium salts, achieving both low-temperature operation and electrochemical performance. The specific ratio and composition of these components are optimized to resolve the contradiction between temperature range and reliability.
2Temperature
If auxiliary solvent is added to lower melting point, then electrolyte solidification problem is solved, but compatibility with positive and negative electrode materials deteriorates and ion transmission ability is affected
Solution Approach 1:
The patent carefully controls the molecular structure parameters of the cyclic carbonate ester solvents (formula I and II), specifically the substituent groups R1-R6, to achieve optimal balance between low-temperature fluidity and electrode compatibility. By adjusting these structural parameters, the solvent maintains appropriate viscosity and solvation power that do not adversely affect carbon electrode materials while ensuring low-temperature operation.
Solution Approach 2:
The patent introduces localized functional groups (R1-R6 substituents) on the cyclic carbonate ester molecules to modify specific interaction properties with electrode materials. These local structural modifications enable the solvent to maintain benign interactions with carbon electrodes while providing the necessary low-temperature performance, thus resolving the contradiction without requiring bulk composition changes that would affect overall electrode compatibility.
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 design improves conductivity and maintains high and low temperature performance, allowing the supercapacitor to function effectively at ultra-low temperatures without deteriorating at high temperatures, with enhanced power density and cycle life.
Implementation Method 1
Electric double-layer supercapacitors store energy by electrostatic polarization of electrolyte, and its energy storage mechanism does not involve chemical reactions, and it is highly reversible.
Implementation Method 2
electrolyte is the heart of 'double electricity', which is used for ion conduction of positive and negative carbon materials
Data Source
AI summary
In order to overcome the problem that the electrochemical performance of the existing supercapacitor is seriously deteriorated at low temperature, the application provides a supercapacitor, comprising a positive electrode, a negative electrode and an organic electrolyte solution, wherein the organic electrolyte solution comprises an organic electrolyte, a proton inert solvent and an additive, and the additive comprises a compound represented by structural formula 1:wherein R1-R6 are each independently selected from a hydrocarbon group with 1-5 carbon atoms, a siloxane group substituted by a hydrocarbon group with 1-3 carbon atoms, an unsubstituted siloxane group, or hydrogen;the positive electrode and negative electrode are both porous carbon materials, and the porous carbon material and the compound represented by structural formula 1 meet the following condition:0.1≤BET*Vt*Mt1700≤7.5.The supercapacitor provided by the application has lower ESR (equivalent series resistance) and better high and low temperature performances.