Lithium Electrode Copolymer Coating for Uniform Li+ Deposition

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Solution Overview

Problem

Lithium metal electrodes in lithium-ion batteries face challenges with dendrite formation and side reactions, leading to reduced battery performance and lifespan, particularly in lithium-sulfur secondary batteries, due to non-uniform ion distribution and inadequate Solid Electrolyte Interphase (SEI) layer formation.

Innovation Solution

A lithium electrode with a protective layer composed of a copolymer containing an acetal functional group and a fluorine-based material is developed, which forms a stable LiF-rich SEI layer, preventing dendrite growth and side reactions by uniformly distributing Li+ ions and enhancing the battery's lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal is used as a negative electrode to increase energy density, then the battery energy density is improved, but lithium dendrite formation occurs leading to internal short circuits and reduced battery lifetime

Engineering Contradiction:

Improveenergy densityVSAvoidbattery lifetime

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A protective layer comprising a copolymer of fluorinated monomer and acetal monomer is introduced as an intermediary between the lithium metal negative electrode and the electrolyte. This protective layer mediates the interaction by providing a controlled interface that prevents direct contact between lithium metal and electrolyte, thereby suppressing dendrite formation and side reactions while maintaining high energy density benefits

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a protective layer is formed on lithium metal to prevent dendrite formation, then battery lifetime is improved, but Li+ ion distribution becomes non-uniform reducing battery performance

Engineering Contradiction:

Improvebattery lifetimeVSAvoidion distribution uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The protective layer composition is specifically designed by copolymerizing fluorinated monomer and acetal monomer in controlled ratios, and the layer thickness is optimized to be 1-10 micrometers. These parameter changes enable the protective layer to maintain both protective functions (preventing dendrites) and ion transport functions (ensuring uniform Li+ distribution)

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protective layer is constructed as a composite material system combining fluorinated polymer and acetal polymer components. This composite structure leverages the complementary properties of both polymers: the fluorinated component provides dendrite suppression while the acetal component facilitates uniform ion distribution, resolving the contradiction between protection and performance

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If conventional protective membranes are used to inhibit dendrite formation, then some protection is provided, but they are insufficient to prevent shuttle phenomenon and effectively form SEI layer in lithium-sulfur batteries

Engineering Contradiction:

Improvedendrite inhibitionVSAvoidshuttle phenomenon prevention

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The protective layer uses specific chemical composition parameters (copolymer of fluorinated and acetal monomers) and physical parameters (thickness of 1-10 micrometers) that are optimized for lithium-sulfur battery applications. These parameter changes enable the protective layer to simultaneously address dendrite inhibition and shuttle phenomenon prevention, which conventional single-function membranes cannot achieve

Inventive Principle:

Principle #35Parameter changes

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 protective layer effectively suppresses lithium dendrite formation and side reactions, thereby increasing the battery's cycle lifetime and stability, especially in lithium-sulfur secondary batteries, by forming a stable and hard SEI layer.

Implementation Method 1

the protective layer comprises a copolymer containing an acetal and a fluorine-based material... forms a stable LiF-rich SEI layer, preventing dendrite growth and side reactions

Methodology Applied

Scientific EffectSolid Electrolyte Interphase (SEI) layer formation:

Implementation Method 2

uniformly distributing Li+ ions on the surface of the electrode... uniformly distributing Li+ ions

Methodology Applied

Scientific EffectIon distribution: Diffusion

Data Source

PatentUS12074318B2Lithium electrode and lithium secondary battery comprising same

Publication Date: 2024.08.27 LG ENERGY SOLUTION LTD

AI summary

A lithium electrode and a lithium secondary battery the same are disclosed. More specifically, a lithium electrode is disclosed that can increase the lifetime of the battery by providing a protective layer containing a copolymer containing an acetal functional group forming a stable SEI layer through a chemical reaction with lithium metal and a fluorine-based functional group capable of forming a LiF-rich SEI layer on the surface of the lithium metal to inhibit the formation of lithium dendrite and inhibit the side reaction of lithium metal and electrolyte solution.