Polymer Electrolyte Composition for Uniform SEI and Thermal Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium secondary batteries face challenges with low discharge characteristics in harsh environments, high temperature durability, and safety issues due to non-aqueous electrolyte solutions causing thermal runaway and non-uniform Solid Electrolyte Interphase (SEI) formation, which affects high-rate lifetime performance and high output characteristics.

Innovation Solution

An electrolyte solution for lithium secondary batteries comprising a polymer compound, lithium salt, and organic solvent, along with specific additives, forms a uniform SEI on electrodes, enhancing high temperature durability and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If non-aqueous electrolyte solution uses ethylene carbonate as main component, then high voltage performance is improved, but thermal runaway and ignition risk increase

Engineering Contradiction:

Improvehigh voltage performanceVSAvoidthermal runaway risk

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance between the ethylene carbonate-based electrolyte and the electrode. This compound preferentially forms a protective SEI film that acts as a mediator, preventing direct contact and harmful reactions between the electrolyte and electrode while maintaining ionic conductivity. The intermediary layer suppresses thermal runaway by creating a stable interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the electrolyte composition by adding fluorinated cyclic carbonate compound at specific concentrations (0.1-5 wt%). This parameter change alters the chemical properties of the electrolyte system, enabling it to form stable SEI films with lower resistance while maintaining high voltage stability. The fluorinated compound changes the decomposition characteristics and thermal stability parameters of the electrolyte.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If high concentration lithium salt and oligomer are used, then high-temperature and low-temperature stability is improved, but pre-gelling phenomenon occurs during wetting

Engineering Contradiction:

Improvetemperature stabilityVSAvoidwetting uniformity

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The patent extracts the problematic oligomer component from the electrolyte formulation and replaces it with fluorinated cyclic carbonate compound. This removal eliminates the pre-gelling phenomenon caused by rapid polymerization of oligomers during wetting, while maintaining the temperature stability benefits through the fluorinated compound's inherent thermal stability and controlled SEI formation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses fluorinated cyclic carbonate compound as a sacrificial additive that consumes itself during initial cycles to form stable SEI films. This disposable-like approach allows the compound to react preferentially and create a protective layer, after which the main electrolyte components remain stable without undergoing unwanted polymerization or gelling.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Productivity

If conventional electrolyte solution is used, then basic battery function is maintained, but high-rate lifetime performance and high output characteristics are poor

Engineering Contradiction:

Improvehigh output characteristicsVSAvoidhigh-rate lifetime performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent creates a composite electrolyte system combining ethylene carbonate, fluorinated cyclic carbonate compound, and lithium salt. This composite formulation synergistically improves both high-rate performance and lifetime characteristics. The fluorinated compound enhances ionic conductivity and SEI stability, enabling the battery to maintain high output while improving resistance to degradation during high-rate cycling.

Inventive Principle:

Principle #40Composite materials

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 improves high-rate lifetime performance, high output characteristics, and safety by controlling heat generation and forming a uniform SEI, thereby preventing resistance increase and improving capacity expression.

Implementation Method 1

forming a uniform SEI on the positive electrode or the negative electrode

Methodology Applied

Scientific EffectSEI formation:

Data Source

PatentUS12456755B2Electrolyte for lithium secondary battery, and lithium secondary battery comprising same

Publication Date: 2025.10.28 LG ENERGY SOLUTION LTD

AI summary

The present disclosure relates to an electrolyte solution for a lithium secondary battery and a lithium secondary battery including the same. More specifically, the electrolyte solution contains the polymer compound represented by Formula 1, and thus can improve high temperature durability, stability, and lifetime characteristics of the lithium secondary battery.