Sulfolane Electrolyte for Low Temperature Power and High Temperature Stability
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Solution Overview
Problem
Lithium ion batteries face performance degradation at low temperatures due to increased electrolyte viscosity, decreased ionic conductivity, and reduced lithium ion diffusion, while high temperature operation is compromised by solvent reactivity and SEI instability, especially with lithium titanate electrodes.
Innovation Solution
The use of sulfolane as a high dielectric solvent combined with low viscosity solvents like methyl butyrate, methyl acetate, and methyl propionate in lithium ion battery electrolyte formulations, which replaces conventional solvents like ethylene carbonate and propylene carbonate, enhances low temperature performance without compromising high temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If solvents with very low melting points and low viscosity are added to improve low temperature performance, then power capability at low temperature is improved, but high temperature cycle life deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using sulfolane (a cyclic sulfone) instead of conventional carbonates, and combines it with specific low-viscosity solvents like dimethyl carbonate and ethyl methyl carbonate in optimized ratios. This parameter change allows the electrolyte to maintain appropriate viscosity and ionic conductivity across both low and high temperature ranges, resolving the contradiction between low-temperature power capability and high-temperature cycle life
Solution Approach 2:
The patent creates a composite electrolyte system by combining sulfolane with specific ratios of low-viscosity carbonate solvents (dimethyl carbonate and ethyl methyl carbonate). This composite formulation leverages the high dielectric constant and thermal stability of sulfolane while using the low-viscosity carbonates to maintain fluidity at low temperatures, achieving both improved low-temperature power capability and preserved high-temperature cycle life
2Reliability
If conventional electrolyte formulations are used to maintain high temperature stability, then high temperature performance is maintained, but low temperature power capability deteriorates
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating sulfolane, which has a high dielectric constant and excellent thermal stability, combined with low-viscosity carbonate solvents. This parameter change enables the electrolyte to maintain stability at high temperatures while the low-viscosity components prevent excessive thickening at low temperatures, thereby improving low-temperature power capability without sacrificing high-temperature stability
3Reliability
If electrolyte viscosity is reduced to improve lithium ion diffusion at low temperature, then ionic conductivity is improved, but high temperature solvent reactivity increases
Solution Approach 1:
The patent changes the viscosity parameter of the electrolyte by combining sulfolane with low-viscosity carbonate solvents in specific ratios. This allows the electrolyte to achieve lower viscosity for improved lithium ion diffusion at low temperatures, while the presence of sulfolane provides thermal stability that suppresses harmful solvent reactivity at high temperatures
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
This approach improves power performance at low temperatures and maintains high temperature stability, achieving wide operating temperature range capabilities without detrimental effects on cycle life.
Implementation Method 1
The electrolyte solution includes a high dielectric solvent and a solvent such as diethyl carbonate, methyl butyrate, methyl acetate, methyl propionate, isobutyl acetate, methyl trimethyl acetate, methyl isovalerate
Implementation Method 2
an increase in viscosity of the electrolyte resulting in slower lithium ion diffusion
Implementation Method 3
slower lithium ion diffusion
Data Source
AI summary
Electrolyte solutions including combinations of high dielectric and low viscosity solvents. These solvent combinations provide low temperature performance and high temperature stability in lithium ion battery cells.