Li-Mg-Al Alloy Negative Electrode for Stable SEI in Lithium Batteries

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Solution Overview

Problem

Lithium-sulfur batteries face issues with the instability of the solid electrolyte interface layer on the lithium metal negative electrode, leading to lithium dendrite formation, internal short circuits, and reduced capacity and lifetime due to the high chemical reactivity of lithium metal with the electrolyte.

Innovation Solution

A lithium-magnesium-aluminum alloy is used as the negative electrode, with a specific composition and properties such as elastic modulus and tensile strength, to stabilize the SEI layer and prevent dendrite formation, comprising a lithium-magnesium-aluminum foil with uniform distribution of magnesium and aluminum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal is used as the negative electrode active material to achieve high capacity and high energy density, then the theoretical specific capacity reaches 3,860 mAh/g and standard reduction potential is -3.045 V, but the high chemical reactivity causes unstable SEI layer formation and lithium dendrite generation

Engineering Contradiction:

Improveenergy densityVSAvoidSEI layer stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the negative electrode by introducing magnesium and aluminum elements to form a multi-element alloy. This compositional parameter change modifies the SEI layer formation characteristics, enabling stable SEI layer formation while maintaining the high energy density benefits of lithium metal.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite negative electrode material by combining lithium metal with magnesium and aluminum elements. This composite structure leverages the high capacity of lithium while the magnesium and aluminum components stabilize the SEI layer, resolving the contradiction between energy density and reliability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium metal is used as the negative electrode active material, then high capacity is achieved, but the SEI layer formed by reaction with electrolyte is weak in mechanical strength and collapses during charging/discharging

Engineering Contradiction:

Improvebattery capacityVSAvoidSEI layer mechanical strength

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The invention modifies the mechanical strength parameter of the SEI layer by changing the negative electrode composition from pure lithium to a lithium-magnesium-aluminum alloy. This compositional change results in an SEI layer with enhanced mechanical strength that maintains structural integrity during battery cycling while preserving high battery capacity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite lithium-magnesium-aluminum alloy negative electrode produces a SEI layer with improved mechanical properties. The magnesium and aluminum components contribute to the SEI layer structure, providing the necessary mechanical strength to prevent collapse during charging and discharging operations.

Inventive Principle:

Principle #40Composite materials

3Use of energy by moving object

If lithium metal is used as the negative electrode active material, then high energy density is realized, but local difference in current density forms lithium dendrite on the surface

Engineering Contradiction:

Improveenergy densityVSAvoidcurrent density uniformity

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The invention changes the surface composition parameters of the negative electrode by incorporating magnesium and aluminum elements. This compositional modification alters the current density distribution characteristics, promoting uniform current density across the electrode surface while maintaining high energy density, thereby preventing lithium dendrite formation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The lithium-magnesium-aluminum composite alloy creates a more uniform current density distribution during battery operation. The presence of magnesium and aluminum elements in the composite structure helps equalize the electrochemical reaction sites, preventing localized current concentration that would lead to dendrite formation while preserving the high energy density advantage.

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 lithium-magnesium-aluminum alloy enhances the battery's life and efficiency by maintaining a stable SEI layer, reducing dendrite formation, and improving cycle lifetime and capacity.

Implementation Method 1

a solid electrolyte interface layer (SEI layer), which is a kind of passivation layer, is formed on the surface of the negative electrode

Methodology Applied

Scientific EffectSolid electrolyte interface layer formation:

Implementation Method 2

since the electrochemical reaction of the battery continuously occurs on the surface of lithium metal

Methodology Applied

Scientific EffectElectrochemical reaction:

Data Source

PatentEP4350796B1Negative electrode for a lithium secondary battery, a method for preparing the same and a lithium secondary battery comprising the same

Publication Date: 2026.01.14 LG ENERGY SOLUTION LTD

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AI summary

The present disclosure relates to a negative electrode for a lithium secondary battery comprising a lithium-magnesium-aluminum alloy, a method for preparing the same and a lithium secondary battery, such as a lithium sulfur battery, comprising the same.