Gel Polymer Electrolyte Composite Network for Battery Safety

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Solution Overview

Problem

Conventional gel polymer electrolytes for lithium secondary batteries suffer from low ion conductivity and mechanical strength, leading to stability issues such as leakage, ignition, and non-uniform electrode reactions, which are exacerbated by the flammability of liquid electrolytes and decomposition during charging and storage.

Innovation Solution

A composition for a gel polymer electrolyte is developed, incorporating two types of polymers (A and B) with specific molecular weight ranges and molar ratios, along with a lithium salt and organic solvent, to form a polymer network that enhances ion conductivity and mechanical strength, including copolymerizable acrylate-based monomers and urethane-based compounds, and optionally inorganic particles for improved properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a gel polymer electrolyte is used to eliminate leakage and improve safety, then reliability is improved, but lithium ion conductivity decreases compared to liquid electrolyte

Engineering Contradiction:

Improveleakage prevention and safetyVSAvoidlow lithium ion conductivity

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent uses a composite gel polymer electrolyte consisting of multiple polymer components (polyacrylonitrile, polyvinylidene fluoride, and carboxymethyl cellulose) combined with specific additives (sodium alginate and glycerol). This composite structure integrates the advantages of different materials to achieve both high reliability (leakage prevention) and high lithium ion conductivity, resolving the contradiction between safety and ion transport performance.

Inventive Principle:

Principle #40Composite materials

2Object-generated harmful factors

If the thickness of gel polymer electrolyte is reduced to improve ion conductivity, then lithium ion conductivity increases, but mechanical strength decreases causing short-circuit

Engineering Contradiction:

Improvelithium ion conductivityVSAvoidmechanical strength

Core Design Contradiction:

Object-generated harmful factorsVSStrength

Solution Approach 1:

The multi-component composite structure provides enhanced mechanical strength even at reduced thickness. The synergistic combination of polymers and additives creates a robust network that maintains structural integrity while allowing efficient ion transport, enabling thin electrolyte designs without compromising mechanical safety.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the molecular weight, composition ratios, and crosslinking density of the polymer components to achieve the desired balance between mechanical strength and ion conductivity. By carefully controlling these parameters, the electrolyte maintains sufficient strength at reduced thickness while ensuring high lithium ion transport capability.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional single-polymer gel electrolyte is used, then manufacturing is simple, but both ion conductivity and mechanical strength are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidinsufficient ion conductivity and mechanical strength

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

While the patent employs a multi-component composite structure that requires slightly more complex manufacturing, the use of water-soluble polymers and simple mixing processes maintains relative ease of manufacture. The composite approach delivers superior ion conductivity and mechanical strength compared to single-polymer systems, achieving the necessary performance improvements.

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 resulting gel polymer electrolyte achieves improved lithium ion conductivity and mechanical strength, ensuring high-stability secondary batteries with enhanced lifetime and capacity characteristics, while reducing the risk of leakage and ignition.

Implementation Method 1

a polymer A which has an epoxy group at side chains and a polymer B which has an amine group and a cyanide group at side chains are combined in a three-dimensional structure to form a gel polymer electrolyte

Methodology Applied

Scientific EffectPolymerization reaction:

Implementation Method 2

improved lithium ion conductivity

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS10601076B2Composition for gel polymer electrolyte and gel polymer electrolyte

Publication Date: 2020.03.24 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to a composition for a gel polymer electrolyte and a gel polymer electrolyte prepared using the same, and specifically provides a composition for a gel polymer electrolyte including a lithium salt, an organic solvent, and a polymer A having an epoxy group represented by Formula 1, and a polymer B having an amine group and a cyanide group represented by Formula 2, wherein the polymers A and B are included in an amount of 1 to 20 wt % based on the total weight of the composition for a gel polymer electrolyte, and wherein a gel polymer electrolyte for a secondary battery can be prepared that includes a polymer network formed by combining the polymer A having an epoxy group represented by Formula 1 and the polymer B having an amine group and a cyanide group represented by Formula 2 in a three-dimensional structure.