Bisphosphate Electrolyte for High-Temperature Lithium Battery Stability

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Solution Overview

Problem

Rechargeable lithium batteries face issues with thermal and chemical stability due to surface damage of nickel-based lithium metal oxide cathode active materials and side reactions with the electrolyte, especially in severe temperature environments, leading to decreased output and capacity.

Innovation Solution

An electrolyte for rechargeable lithium batteries comprising an additive represented by Formula 1, an organic solvent, and a lithium salt, with optional auxiliary additives, stabilizes the electrode interface and forms a stable solid electrolyte interface film (SEI) to enhance thermal and chemical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If nickel-based lithium metal oxide is used as cathode active material to achieve high capacity, then battery capacity is improved, but surface damage and side reactions occur leading to decreased stability

Engineering Contradiction:

Improvebattery capacityVSAvoidthermal and chemical stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A compound containing phosphorus and fluorine atoms acts as an intermediary substance between the nickel-based cathode material and the electrolyte. This compound forms a stable interfacial layer that mediates the interaction, preventing direct harmful contact while allowing beneficial electrochemical reactions to proceed, thus resolving the contradiction between high capacity and stability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition parameters of the electrolyte by introducing a specific compound with phosphorus and fluorine atoms. This parameter change transforms the interfacial chemistry between electrode and electrolyte, creating a more stable interface that maintains high capacity while improving thermal and chemical stability

Inventive Principle:

Principle #35Parameter changes

2Duration of action of moving object

If repeated charging and discharging is performed to increase battery lifespan, then operational duration is improved, but surface damage accumulates and output decreases

Engineering Contradiction:

Improvebattery lifespanVSAvoidbattery output

Core Design Contradiction:

Duration of action of moving objectVSPower

Solution Approach 1:

The phosphorus-fluorine compound performs preliminary protective action by forming a stable interfacial layer before extensive charging-discharging cycles begin. This pre-formed protective layer prevents cumulative surface damage during repeated operations, maintaining battery output over extended lifespan

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The compound provides beforehand cushioning by creating a buffer layer at the electrode-electrolyte interface that absorbs and mitigates the harmful effects of repeated charging-discharging stress, preventing direct damage to the cathode material surface and preserving battery output

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If battery operates in severe high temperature environment to meet application requirements, then adaptability is improved, but thermal stability deteriorates and side reactions increase

Engineering Contradiction:

Improveenvironmental adaptabilityVSAvoidthermal stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The phosphorus-fluorine compound converts the potentially harmful high-temperature environment into a beneficial condition by forming an even more stable interfacial layer at elevated temperatures. The compound's thermal properties enable it to thrive in high-temperature conditions, protecting the electrode while allowing the battery to operate adaptively in severe environments

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 electrolyte improves battery performance by reducing heat generation, enhancing flame retardancy, and maintaining high-temperature storage and discharge characteristics, thereby stabilizing the electrode interface and improving capacity and lifespan.

Implementation Method 1

forms a stable solid electrolyte interface film (SEI) to enhance thermal and chemical stability

Methodology Applied

Scientific EffectSolid electrolyte interface (SEI) formation:

Implementation Method 2

reducing heat generation, enhancing flame retardancy

Methodology Applied

Scientific EffectHeat reduction:

Data Source

PatentUS20260074281A1Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Publication Date: 2026.03.12 SK ON CO LTD

AI summary

An electrolyte for a rechargeable lithium battery of exemplary embodiments includes: an organic solvent; a lithium salt; and a bisphosphate-based additive, thereby providing an electrolyte for a rechargeable lithium battery capable of imparting improved flame retardant characteristics and cell performance, for example, high-temperature storage characteristics and lifespan characteristics, and a rechargeable lithium battery including the same.