Cylindrical Lithium Battery Electrolyte for High-Temperature Resistance
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Solution Overview
Problem
Rechargeable lithium batteries face issues with increased resistance at high temperatures and reduced cycle-life, particularly when using a cylindrical can, which worsens with variations in can volume.
Innovation Solution
Incorporating a non-aqueous organic solvent, a lithium salt with a lithium imide salt, and an electrolyte additive represented by Chemical Formula 1, within specific concentration ranges, to control the volume of the cylindrical can and improve high-temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cylindrical can is used to house the electrode assembly, then the battery structure is simplified and manufacturing is easier, but resistance increases at high temperatures and cycle-life is reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the volume of the cylindrical can within a specific range (10-140 cm³) and adjusting the electrolyte composition (adding 0.1-5 wt% fluoroethylene carbonate and 5-30 wt% lithium imide salt). These parameter modifications resolve the contradiction by maintaining manufacturing simplicity while significantly improving high-temperature resistance stability and cycle-life performance.
Solution Approach 2:
The patent uses composite materials by combining multiple electrolyte components (lithium salt, non-aqueous organic solvent, fluoroethylene carbonate additive, and lithium imide salt) in specific proportions. This composite electrolyte system works synergistically to suppress resistance increase at high temperatures while maintaining the simple cylindrical can structure, thus resolving the contradiction between manufacturing ease and reliability.
2Use of energy by moving object
If the cylindrical can volume is increased to accommodate more electrode material, then energy density is improved, but high-temperature resistance increase becomes more severe
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal volume range for the cylindrical can (10-140 cm³) and combining it with specific electrolyte composition parameters (additive concentration and lithium imide salt content). This multi-parameter optimization allows the battery to achieve high energy density while suppressing the harmful effect of resistance increase at high temperatures.
Solution Approach 2:
The patent introduces the lithium imide salt and fluoroethylene carbonate as intermediary substances that mediate between the electrode assembly and the electrolyte. These intermediaries form protective interfaces that reduce direct harmful interactions at high temperatures, allowing larger can volumes to be used without proportionally increasing resistance, thus enabling higher energy density with controlled resistance increase.
3Ease of manufacture
If conventional electrolyte composition is used to maintain cost-effectiveness, then manufacturing cost is reduced, but cycle-life is reduced at high temperatures
Solution Approach 1:
The patent applies parameter changes by optimizing the concentrations of electrolyte components within cost-effective ranges: 0.1-5 wt% fluoroethylene carbonate and 5-30 wt% lithium imide salt. These parameter adjustments significantly extend cycle-life at high temperatures while maintaining reasonable manufacturing costs, resolving the contradiction between cost-effectiveness and durability.
Solution Approach 2:
The patent addresses cycle-life extension by using electrolyte additives that prevent degradation and recover performance. The fluoroethylene carbonate and lithium imide salt form stable protective layers on electrode surfaces that prevent further degradation during cycling, effectively extending the battery's operational life without requiring expensive material substitutions.
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 effectively suppresses resistance increases at high temperatures and enhances cycle-life by optimizing the electrolyte composition and can volume, as demonstrated in various examples with improved capacity retention and resistance management.
Implementation Method 1
a rechargeable lithium battery including a cylindrical can having a volume of 10 to 140 cubic centimeter (cm³) wherein, in Chemical Formula (1), X₁ is a halogen atom; Y₁ and Y₂ are each independently be O or S; and R₁ and R₂ are each independently H, a halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, vinyl group, a substituted or unsubstituted C6 to C10 aryl group, or a substituted or unsubstituted C2 to C10 heteroaryl group including a hetero atom of N, O, S, or P
Implementation Method 2
The rechargeable lithium battery can suppress or reduce an increase in resistance at high temperatures and/or improve or secure its cycle-life by adding an electrolyte additive and a lithium imide salt while controlling the volume of the cylindrical can
Data Source
Figure 1
AI summary
A rechargeable lithium battery including a cylindrical can; an electrode assembly in the cylindrical can; and an electrolyte in the electrode assembly is provided. An electrolyte additive and a lithium imide salt are included in the electrolyte and the volume of a cylindrical can is well-defined.