Nonaqueous Electrolyte Composition for Li-Ion Cycling and DC Resistance
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Solution Overview
Problem
Batteries with nonaqueous electrolyte solutions, such as lithium-ion batteries, face challenges in achieving concurrent improvements in high-temperature durability and low-temperature direct-current resistance performance, particularly in vehicles like electric vehicles.
Innovation Solution
A nonaqueous electrolyte solution for lithium-ion batteries comprising specific percentages of fluoroethylene carbonate, ethyl propionate, 1,2,3-tris(2-cyanoethoxy)propane, and a nitrogen-containing lithium salt, which form a stable coating on the positive electrode surface, reducing resistance and electrode expansion, thereby enhancing both high-temperature cycling and low-temperature direct-current resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additives are used to suppress deterioration, then the decomposition of nonaqueous electrolyte solutions on electrode surfaces is reduced, but the volume resistance of the positive electrode and expansion of the negative electrode still occur
Solution Approach 1:
The patent uses fluoroethylene carbonate and 1,2,3-tris(2-cyanoethoxv)propane as intermediary substances that form protective interface layers between the electrolyte and electrode surfaces. These additives preferentially react with electrode surfaces to create stable solid electrolyte interphase (SEI) layers that prevent direct contact between the bulk electrolyte and active materials. This intermediary layer acts as a barrier that suppresses electrolyte decomposition while simultaneously reducing volume resistance by providing stable ionic transport pathways and preventing electrode expansion through mechanical buffering.
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 alleviates volume resistance and electrode expansion, achieving balanced performance in high-temperature cycling and low-temperature direct-current resistance.
Implementation Method 1
the nonaqueous electrolyte solution contains: (I) fluoroethylene carbonate, (II) ethyl propionate, (III) 1,2,3-tris(2-cyanoethoxy)propane, and (IV) a nitrogen-containing lithium salt... form a stable coating on the positive electrode surface
Data Source
AI summary
A nonaqueous electrolyte solution includes a nonaqueous solvent and a lithium salt dissolved in a specific amount in the nonaqueous solvent. The nonaqueous electrolyte solution contains a specific amount of fluoroethylene carbonate, ethyl propionate, 1,2,3-tris(2-cyanoethoxy)propane, and a nitrogen-containing lithium salt. Based on a mass of the nonaqueous electrolyte solution, an aggregate mass percentage of the fluoroethylene carbonate and the 1,2,3-tris(2-cyanoethoxy)propane in the nonaqueous electrolyte solution is set to fall within a specific range. An aggregate mass percentage of the ethyl propionate and the nitrogen-containing lithium salt is set to fall within a specific range. This application can alleviate the volume resistance of a positive electrode and expansion of a negative electrode of the lithium-ion battery, and make the battery exhibit good high-temperature cycling performance and low-temperature direct-current resistance performance.