Lithium Battery Electrolyte Additive for High-Temperature Cathode Protection

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Solution Overview

Problem

Lithium secondary batteries face issues with reduced power and capacity due to surface damage of nickel-based lithium metal oxide cathodes, especially under high-temperature conditions, leading to increased internal resistance and shortened lifespan.

Innovation Solution

An electrolyte solution is developed containing a specific additive represented by Chemical Formula 1, an organic solvent, and a lithium salt, which forms a robust solid electrolyte interphase (SEI) on the electrodes, enhancing high-temperature storage properties and overall battery performance by reducing resistance and gas generation.

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 occurs leading to reduced power and capacity retention

Engineering Contradiction:

Improvebattery capacityVSAvoidpower retention

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance that mediates between the nickel-based cathode and the electrolyte. This compound forms a protective interface layer that prevents direct harmful interactions while allowing ionic transport, thus resolving the contradiction between high capacity and power retention

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (Formula 1 where R1-R6 are specific combinations of H, F, and alkyl groups). This parameter change in electrolyte composition leads to formation of a stable SEI layer that maintains both capacity and power over cycles

Inventive Principle:

Principle #35Parameter changes

2Speed

If the battery operates in high-temperature environment to achieve higher reaction rates, then charging/discharging speed is improved, but internal resistance increases and lifespan decreases

Engineering Contradiction:

Improvecharging/discharging rateVSAvoidbattery lifespan

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The patent applies preliminary action by having the fluorinated cyclic carbonate compound react first during initial cycles to form a stable solid electrolyte interphase (SEI) layer before the battery undergoes normal operation. This pre-formed protective layer prevents subsequent degradation reactions that would otherwise occur at high temperatures, thus extending lifespan while maintaining high-rate capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potentially harmful high-temperature conditions into a benefit by using them to accelerate the formation of a robust SEI layer containing the fluorinated cyclic carbonate compound. This layer, once formed, protects the battery during subsequent high-temperature operation, transforming the harmful thermal environment into a condition that strengthens the protective interface

Inventive Principle:

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

3Duration of action of stationary object

If the electrolyte composition is modified to reduce side reactions, then battery lifespan is improved, but ionic conductivity may be affected

Engineering Contradiction:

Improvebattery lifespanVSAvoidionic conductivity

Core Design Contradiction:

Duration of action of stationary objectVSLoss of energy

Solution Approach 1:

The patent applies local quality by concentrating the fluorinated cyclic carbonate compound specifically at the electrode-electrolyte interface where side reactions occur, rather than uniformly throughout the entire electrolyte. This localized modification protects the electrodes from degradation while maintaining the bulk electrolyte's ionic conductivity for efficient lithium ion transport

Inventive Principle:

Principle #3Local quality

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 capacity retention, reduces initial resistance, and extends the battery's lifespan at both high and low temperatures, while maintaining lithium ion mobility and cathode active material activity.

Implementation Method 1

An electrolyte solution including an additive according to example embodiments may form a robust solid electrolyte interphase (SEI) on an electrode surface

Methodology Applied

Scientific EffectSolid electrolyte interphase (SEI) formation:

Implementation Method 2

the above-described problems are accelerated, causing a battery expansion (gas generation at an inside of the battery, increase of a battery thickness)

Methodology Applied

Scientific EffectGas generation reduction:

Data Source

PatentEP4287336A1Electrolyte solution for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2023.12.06 SK INNOVATION CO LTD

Figure 1~2

AI summary

According to the present disclosures, an electrolyte solution for a lithium secondary battery and a lithium secondary battery including the electrolyte solution are provided. The electrolyte solution includes an additive represented by a specific chemical formula, an organic solvent and a lithium salt. The lithium secondary battery including the electrolyte solution provide enhanced high-temperature properties.