Lithium Metal Negative Electrode Polymer Electrolyte Dendrite Control

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Solution Overview

Problem

Rechargeable lithium batteries face challenges with lithium metal dendrite formation, reactivity with organic electrolytes, and limited cycle life characteristics, which are not adequately addressed by carbonaceous materials.

Innovation Solution

A rechargeable lithium polymer battery design using lithium metal deposited on a substrate as the negative electrode and a polymer electrolyte to inhibit dendrite formation and enhance cycle life, with a gel polymer electrolyte prepared by polymerizing a monomer and an initiator in an organic solvent containing a lithium salt.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal is used as negative active material, then energy density is improved, but dendrite formation occurs and cycle life deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidcycle life

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A polymer electrolyte is introduced as an intermediary between the lithium metal negative electrode and the positive electrode. This polymer electrolyte acts as a mediator that prevents direct contact and harmful reactions between lithium metal and organic electrolytes, while still allowing ionic conduction. The polymer electrolyte forms a stable interface with lithium metal, preventing dendrite formation and improving cycle life while maintaining the high energy density benefits of lithium metal.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If carbonaceous materials are used as negative active material, then dendrite formation is prevented, but power density deteriorates due to slow lithium diffusion

Engineering Contradiction:

Improvedendrite preventionVSAvoidpower density

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The polymer electrolyte serves as an intermediary that enables the use of lithium metal without the harmful effects. It provides a stable interface that prevents dendrite formation while maintaining high ionic conductivity, thus achieving both dendrite prevention and high power density that carbonaceous materials cannot provide.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If lithium metal is used as negative active material, then energy density is improved, but reactivity with electrolyte increases causing polymer film formation

Engineering Contradiction:

Improveenergy densityVSAvoidreactivity with electrolyte

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The polymer electrolyte acts as a protective intermediary layer between lithium metal and the organic electrolyte. It prevents direct contact and harmful chemical reactions between lithium metal and the organic electrolyte, which would otherwise form non-conductive polymer films on the lithium surface. The polymer electrolyte maintains ionic conductivity while protecting the lithium metal from degradation.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If liquid electrolyte is used, then ionic conductivity is maintained, but electrolyte movement causes damage to lithium metal

Engineering Contradiction:

Improveionic conductivityVSAvoidelectrolyte movement damage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The electrolyte is transformed from a liquid state to a gel polymer state by incorporating it into a polymer matrix. This parameter change maintains the ionic conductivity necessary for battery operation while eliminating the free movement of the electrolyte. The gel polymer electrolyte provides a fixed, stable structure that prevents electrolyte movement from damaging the lithium metal electrode while preserving the essential ionic conduction pathways.

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 solution provides improved cycle life characteristics and prevents electrolyte movement, reducing damage to lithium metal and enhancing energy density and ionic conductivity, resulting in better performance compared to batteries with liquid electrolytes.

Implementation Method 1

a polymer electrolyte is used in order to solve shortcomings associated with the reaction between lithium metal and an electrolytic solution. Thus, the present invention can provide a rechargeable lithium battery exhibiting good cycle life characteristics.

Methodology Applied

Scientific EffectDendrite formation inhibition:

Implementation Method 2

a gel polymer electrolyte prepared by polymerizing a monomer and an initiator in an organic solvent containing a lithium salt

Methodology Applied

Scientific EffectGelation: Gel

Implementation Method 3

lithium metal is deposited on a substrate in order to inhibit dendrite formation of a bare lithium metal negative electrode

Methodology Applied

Scientific EffectElectrochemical deposition: Electrodeposition

Data Source

PatentUS7745048B2Rechargeable lithium polymer battery

Publication Date: 2010.06.29 SAMSUNG SDI CO LTD

AI summary

Disclosed is a rechargeable lithium polymer battery comprising a negative electrode including a negative active material layer deposited on a substrate, a positive electrode including a positive active material; and a polymer electrolyte including a lithium salt, an organic solvent, and a polymer.