Lithium Ion Capacitor Electrolyte for Low-Temperature Stability
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Solution Overview
Problem
Lithium ion capacitors face challenges in maintaining low internal resistance and high capacitance at low temperatures while ensuring reliability at high temperatures due to electrolyte decomposition and increased viscosity, which affects their performance and longevity.
Innovation Solution
A lithium ion capacitor with an electrolytic solution comprising 100 parts of solvent, including 20 to 50 parts propylene carbonate, 10 to 35 parts dimethyl carbonate, and 15 to 70 parts ethyl methyl carbonate, and lithium bis(fluorosulfonyl)imide as the electrolyte, which maintains initial performance across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-concentration electrolytic solution of LiFSI is used to improve characteristics, then battery characteristics improve, but ion dissociation decreases and internal resistance rises significantly
Solution Approach 1:
The patent optimizes the electrolyte concentration parameter to a specific range (1.0-1.6 mol/L LiFSI) rather than using high concentration. This parameter optimization balances ion dissociation (favored by lower concentration) with film formation and stability (favored by higher concentration), resolving the contradiction between battery characteristics and internal resistance
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 achieves minimal changes in capacitance and internal resistance, maintaining high capacitance and low internal resistance even after exposure to high-temperature, high-voltage environments, outperforming prior art in reliability and performance stability.
Implementation Method 1
the higher the concentration of the electrolytic solution, the lower the degree of ion dissociation becomes
Implementation Method 2
reduced electrolyte dissociation in the electrolytic solution and rise in the viscosity of the electrolytic solution
Implementation Method 3
deterioration in cell characteristics as a result of decomposition of PF6− and other anions constituting the electrolyte and consequent generation of hydrogen fluoride and other decomposition products
Data Source
AI summary
A lithium ion capacitor has an electrolytic solution that contains: 100 parts by volume of a solvent containing 20 to 50 parts by volume of propylene carbonate, 10 to 35 parts by volume of dimethyl carbonate, and 15 to 70 parts by volume of ethyl methyl carbonate; and lithium bis(fluorosulfonyl)imide, as an electrolyte. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes in a low-temperature environment, even after exposure to a high-temperature, high-voltage environment.