LFP Battery Electrolyte Additives for High-Temperature Stability

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Solution Overview

Problem

Lithium secondary batteries with lithium iron phosphate (LFP) positive electrodes face degradation due to electrolyte decomposition and metal ion elution at high temperatures, leading to structural instability and performance issues.

Innovation Solution

Incorporating a specific additive combination in the non-aqueous electrolyte, comprising a primary amine and a propargyl functional group-containing compound, forms stable solid electrolyte interface (SEI) and cathode electrolyte interface (CEI) films, inhibiting metal ion elution and enhancing thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If lithium iron phosphate (LFP) positive electrode material is used, then structural stability is improved, but electrolyte decomposition and metal ion elution deepen

Engineering Contradiction:

Improvestructural stabilityVSAvoidmetal ion elution

Core Design Contradiction:

Stability of the object's compositionVSLoss of substance

Solution Approach 1:

The patent introduces a mediator substance (specific additive compound with formula (1)) that interacts with both the LFP positive electrode and the electrolyte. This additive forms a protective interface layer that prevents direct harmful interactions between the electrode and electrolyte, thereby reducing metal ion elution while maintaining structural stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrolyte by adding specific compounds (formula (1) and formula (2))) to change the interface properties between electrode and electrolyte. This parameter change reduces the elution rate of metal ions without compromising the structural stability of the LFP electrode.

Inventive Principle:

Principle #35Parameter changes

2Power

If high temperature operation is performed, then battery power and reaction rate are improved, but electrolyte decomposition accelerates

Engineering Contradiction:

Improvebattery powerVSAvoidelectrolyte decomposition

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent applies preliminary anti-action by adding protective additives (formulas (1) and (2))) to the electrolyte before high-temperature operation occurs. These additives pre-form protective films on the electrode surfaces that prevent subsequent thermal decomposition of the electrolyte, thereby maintaining battery power while reducing energy loss through decomposition.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful effect of high temperature into a beneficial outcome by using the thermal energy to drive the formation of stable protective films through the additive compounds. These films then prevent further harmful decomposition, effectively converting the potentially damaging high-temperature condition into a mechanism for creating protective barriers.

Inventive Principle:

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

3Reliability

If PF6− anion is used in electrolyte, then ionic conductivity is improved, but thermal decomposition generates HF

Engineering Contradiction:

Improveionic conductivityVSAvoidHF generation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces intermediary compounds (formulas (1) and (2))) that act as buffers between the PF6− anion and moisture. These intermediaries preferentially react with any generated HF or prevent its formation, while allowing the PF6− anion to maintain its ionic conductivity function. This resolves the contradiction by decoupling the conductivity benefit from the harmful HF generation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 additive combination improves high-temperature performance by reducing electrolyte decomposition and metal ion elution, thereby enhancing the battery's lifespan and resistance characteristics.

Implementation Method 1

Methodology Applied

Scientific EffectSolid electrolyte interface (SEI) formation:

Implementation Method 2

Methodology Applied

Scientific EffectCathode electrolyte interface (CEI) formation:

Implementation Method 3

enhancing thermal stability

Methodology Applied

Scientific EffectThermal stability enhancement:

Implementation Method 4

inhibiting metal ion elution

Methodology Applied

Scientific EffectMetal ion elution inhibition:

Data Source

PatentUS12424661B2Lithium secondary battery

Publication Date: 2025.09.23 LG ENERGY SOLUTION LTD

AI summary

The present disclosure relates to a lithium secondary battery including: a non-aqueous electrolyte including a lithium salt, an organic solvent, a first additive represented by Chemical Formula 1 and a second additive represented by Chemical Formula 2; a positive electrode including a positive electrode active material including a lithium iron phosphate-based composite oxide; a negative electrode including an negative electrode active material; and a separator interposed between the positive electrode and the negative electrode.