Lithium Battery Electrolyte Compound for SEI Stability and Output

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Solution Overview

Problem

Existing lithium secondary batteries face challenges in improving life-span characteristics and output characteristics, particularly in applications requiring high performance like electric vehicles.

Innovation Solution

A novel compound represented by Formula 1 is incorporated into the electrolyte, which is prepared by reacting a sulfonate-based or sulfate-based salt with an alkali metal phosphate-based salt, forming a solid electrolyte interface (SEI) film that enhances conductivity and reduces decomposition of organic solvents, thereby improving battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If conventional electrolyte compositions are used, then the battery can operate, but life-span characteristics and capacity retention rate deteriorate during repeated charging and discharging

Engineering Contradiction:
Improvelife-span characteristicsVSAvoidcapacity retention rate
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent introduces a novel compound with specific molecular structure (Formula 1) containing P, S, F, and Li elements, where the chemical composition and atomic ratios are precisely controlled (P: 0.1-5.0 wt%, S: 0.1-5.0 wt%, F: 0.1-5.0 wt%, Li: 0.1-5.0 wt%). This parameter optimization enables the compound to form a stable SEI film that improves capacity retention rate while extending battery life-span through repeated charging-discharging cycles.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining the novel compound (containing P, S, F, Li) with conventional electrolyte components. This composite approach allows the novel compound to form a protective SEI film on the anode while maintaining the overall electrolyte's conductivity and solvation capabilities, thereby simultaneously improving life-span characteristics and capacity retention rate.

Inventive Principle:
Principle #40Composite materials

2Power

If electrolyte composition is varied to improve output characteristics, then conductivity of lithium ions may be enhanced, but life-span characteristics may deteriorate

Engineering Contradiction:
Improveoutput characteristicsVSAvoidlife-span characteristics
Core Design Contradiction:
PowerVSDuration of action of stationary object

Solution Approach 1:

The patent optimizes the concentration parameters of the novel compound in the electrolyte (P: 0.1-5.0 wt%, S: 0.1-5.0 wt%, F: 0.1-5.0 wt%, Li: 0.1-5.0 wt%) to achieve a balance between output characteristics and life-span characteristics. The compound forms a stable SEI film that reduces resistance and improves lithium ion conductivity, enhancing power output while the stable film structure prevents degradation during long-term cycling, thereby extending battery life.

Inventive Principle:
Principle #35Parameter changes

3Duration of action of stationary object

If a solid electrolyte interface (SEI) film is firmly formed on the anode, then life-span characteristics improve, but conductivity of lithium ions may be reduced

Engineering Contradiction:
Improvelife-span characteristicsVSAvoidconductivity of lithium ions
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent applies the novel compound specifically at the anode interface where it forms a protective SEI film with different properties than the bulk electrolyte. The SEI film has high stability and low resistance characteristics that improve life-span, while the bulk electrolyte maintains high lithium ion conductivity. This local differentiation allows simultaneous achievement of long battery life and high conductivity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The novel compound acts as an intermediary that forms a SEI film between the anode and the bulk electrolyte. This SEI film serves as a mediator that protects the anode from degradation (improving life-span) while maintaining adequate lithium ion transport (preserving conductivity). The compound's molecular structure with P, S, F, and Li elements enables it to fulfill both protective and conductive functions.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 novel compound improves the life-span characteristics and output characteristics of lithium secondary batteries by forming a stable SEI film, reducing cathode interface resistance, and enhancing lithium ion mobility.

Implementation Method 1

forming a solid electrolyte interface (SEI) film that enhances conductivity and reduces decomposition of organic solvents

Methodology Applied
Scientific EffectSolid electrolyte interface (SEI) film formation:

Implementation Method 2

a process of intercalating and deintercalating lithium ions from lithium metal oxide particles and graphite is repeated, such that charging and discharging may be performed

Methodology Applied
Scientific EffectIntercalation:

Data Source

PatentEP4371995B1Novel compound, electrolyte solution for secondary battery comprising same, and secondary battery comprising same
Publication Date: 2025.10.08 DONGWHA ELECTROLYTE CO LTD
  • EP4371995B1 patent drawingFigure 1
  • EP4371995B1 patent drawingFigure 2~4
  • EP4371995B1 patent drawingFigure 5

AI summary

According to exemplary embodiments of the present invention, there is provided a novel compound represented by a specific formula. The electrolyte for a lithium secondary battery according to exemplary embodiments may include the compound.