Phosphazene Battery Electrolyte for Internal Short-Circuit Heat Suppression

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Solution Overview

Problem

Existing lithium secondary batteries face challenges in inhibiting a rapid increase in temperature during internal short circuits due to the lack of effective additives in their non-aqueous electrolytes.

Innovation Solution

Incorporating a phosphazene compound, represented by specific formulas, into the non-aqueous electrolyte solution, which forms a coating film on metal surfaces during short circuits, increasing electronic resistance and inhibiting heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional non-aqueous electrolyte solutions are used, then the battery operates normally, but the rate of temperature increase accelerates rapidly during internal short circuits

Engineering Contradiction:
Improvesafety during internal short circuitVSAvoidrate of temperature increase
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The phosphazene compound acts as an intermediary substance that mediates between the metal surface and the electrolyte. It forms a coating film on the metal surface, which serves as an intermediate layer to increase electronic resistance and suppress heat generation during internal short circuits, thereby resolving the contradiction between normal operation and safety during abnormal conditions

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition parameter of the electrolyte by introducing phosphazene compounds with specific molecular structures (Formula 1 and Formula 2). This parameter change enables the formation of protective coating films on metal surfaces, fundamentally altering the electrical and thermal properties of the electrolyte system to suppress temperature increase rates during short circuits

Inventive Principle:
Principle #35Parameter changes

2Reliability

If additives are incorporated into improve battery performance, then battery performance improves, but the complexity of the electrolyte composition increases

Engineering Contradiction:
Improvebattery performanceVSAvoidelectrolyte composition complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The phosphazene compound exhibits multi-functionality: it serves as both a performance-enhancing additive and a safety protective agent. By forming coating films on metal surfaces, it simultaneously improves battery performance and prevents thermal runaway during short circuits, thereby achieving multiple benefits without proportionally increasing system complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention creates a composite electrolyte system by combining phosphazene compounds with conventional electrolyte components. This composite approach integrates the beneficial properties of phosphazene (coating formation, high resistance) with the established performance of conventional electrolytes, achieving enhanced reliability without excessive complexity

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 phosphazene compound effectively reduces the rate of temperature increase during internal short circuits by forming a coating film that enhances electronic resistance, thereby safeguarding the battery.

Implementation Method 1

the phosphazene compound (A), when incorporated into a non-aqueous electrolyte solution for a battery, can inhibit an increase in a rate of temperature increase inside the battery in the event of an internal short circuit

Methodology Applied
Scientific EffectCoating film formation: Deposition (physical)

Implementation Method 2

the phosphazene compound (A) that contains at least one of a phosphazene compound represented by the following Formula (1) or a phosphazene compound represented by the following Formula (2)

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP4131548B1Non-aqueous electrolyte for battery, precursor for lithium secondary battery, method for manufacturing lithium secondary battery, lithium secondary battery, phosphazene compound, and additive for battery
Publication Date: 2025.08.27 MITSUI CHEMICALS INC
  • EP4131548B1 patent drawingFigure 1
  • EP4131548B1 patent drawingFigure 2
  • EP4131548B1 patent drawing

AI summary

A non-aqueous electrolyte solution for a battery contains a phosphazene compound (A) that contains at least one of a phosphazene compound represented by Formula (1) or a phosphazene compound represented by Formula (2). In Formulae (1) and (2), each of Y- and Z- independently represents an anion in which a proton is removed from an inorganic acid or an active hydrogen compound; each of twenty-four Rs independently represents a hydrocarbon group having from 1 to 10 carbon atoms; and, among the twenty-four Rs, two Rs bonded to the same nitrogen atom are optionally bonded to each other.