Nonaqueous Electrolyte Composition for Li-Ion Temperature Balance

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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 containing specific percentages of fluoroethylene carbonate, ethyl propionate, 1,2,3-tris(2-cyanoethoxy)propane, and nitrogen-containing lithium salts, 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

VSEngineering Contradiction Analysis

1Reliability

If conventional nonaqueous electrolyte solutions are used, then the battery can operate, but the durability at high temperature and direct-current resistance performance at low temperature cannot be improved concurrently

Engineering Contradiction:

Improvehigh-temperature durabilityVSAvoidlow-temperature direct-current resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite electrolyte system combining multiple components: fluoroethylene carbonate (FEC) as film-forming additive, ethyl propionate (EP) as main solvent, 1,2,3-tris(2-cyanoethoxy)propane (TCEP) as co-solvent, and nitrogen-containing lithium salts (LiN(SO2CF3)2 or LiN(CF3SO2)(SO2C2F5)) as electrolyte salt. This composite formulation creates synergistic effects that simultaneously improve high-temperature stability and low-temperature conductivity, resolving the contradiction between these two performance aspects.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes specific concentration parameters of each component: FEC at 2.1-9 wt%, EP at 5-35 wt%, TCEP at 0.7-5 wt%, and nitrogen-containing lithium salt at 0.01-5 wt%. These parameter adjustments modify the electrolyte's physical and chemical properties to achieve balanced performance across different temperature conditions, transforming the electrolyte's characteristics to resolve the temperature-dependent performance contradiction.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If additives are used to suppress decomposition, then electrode surface stability improves, but the volume resistance of positive electrode and expansion of negative electrode increase

Engineering Contradiction:

Improveelectrode surface stabilityVSAvoidelectrode volume expansion

Core Design Contradiction:

Stability of the object's compositionVSVolume of stationary object

Solution Approach 1:

The nitrogen-containing lithium salts act as intermediaries that form stable interfacial films on electrode surfaces. These films serve as protective barriers that suppress electrolyte decomposition while maintaining ion transport. The specific nitrogen-containing anions (N(SO2CF3)2-, N(CF3SO2)(SO2C2F5)-) mediate the interaction between electrolyte and electrode, preventing direct harmful reactions while controlling film formation to minimize volume expansion.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates different functional layers with distinct properties: a stable protective film on the positive electrode surface (reducing resistance) and a controlled SEI layer on the negative electrode (suppressing expansion). Each electrode interface receives tailored protection through the electrolyte composition, with local quality variations addressing specific electrode requirements rather than applying uniform treatment.

Inventive Principle:

Principle #3Local quality

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, improving the overall battery performance.

Implementation Method 1

the nonaqueous electrolyte solution contains... a nitrogen-containing lithium salt... which form a stable coating on the positive electrode surface

Methodology Applied

Scientific EffectElectrochemical reaction:

Implementation Method 2

alleviates the volume resistance of the positive electrode

Methodology Applied

Scientific EffectSurface modification:

Implementation Method 3

alleviates... the expansion of the negative electrode

Methodology Applied

Scientific EffectVolume stabilization:

Data Source

PatentUS20250309355A1Nonaqueous electrolyte solution, lithium-ion battery, and electronic device

Publication Date: 2025.10.02 NINGDE AMPEREX TECHNOLOGY LTD

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.