Lithium Nitride and Carbon Coated Anode for Dendrite Suppression

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Solution Overview

Problem

Lithium secondary batteries face stability and performance decline due to lithium dendrite formation during charge and discharge, with existing suppression methods being ineffective.

Innovation Solution

A negative electrode is developed with a lithium nitride thin film layer and a carbon-based thin film layer on a lithium metal layer, where the lithium nitride layer has a porosity of 30% or less and the carbon-based layer has a specific surface area of 50 m2/g or greater, formed using methods like sputtering or chemical vapor deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a lithium metal layer is used as a negative electrode, then high energy density is achieved, but lithium dendrite formation occurs leading to stability degradation

Engineering Contradiction:

Improveenergy densityVSAvoidstability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A lithium nitride layer is introduced as an intermediary between the lithium metal layer and the electrolyte. This intermediate layer prevents direct contact between lithium metal and electrolyte, blocking side reactions and dendrite formation while maintaining the high energy density benefits of lithium metal.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The negative electrode is designed as a composite structure combining lithium metal layer with lithium nitride layer. This composite material approach allows the system to simultaneously achieve the high energy density of lithium metal and the stability of lithium nitride, resolving the contradiction between energy density and reliability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If polymer protective layer or inorganic solid protective layer is introduced to lithium metal layer, then some protection is provided, but lithium dendrite suppression effects are insignificant

Engineering Contradiction:

Improveprotection against dendriteVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention changes the chemical composition parameter of the protective layer from conventional polymers or inorganic solids to lithium nitride. This parameter change results in significantly enhanced dendrite suppression effects while maintaining a simple single-layer structure, avoiding increased device complexity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If concentration of salt in electrolyte liquid is increased or additives are used, then some dendrite suppression is achieved, but effects are insignificant

Engineering Contradiction:

Improvedendrite suppressionVSAvoidelectrolyte composition complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of modifying the electrolyte composition with higher salt concentrations or additives, the invention extracts the protective function from the electrolyte and transfers it to the electrode structure by forming a lithium nitride layer on the lithium metal. This approach achieves significant dendrite suppression without complicating the electrolyte formulation.

Inventive Principle:

Principle #2Taking out (Extraction)

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

This configuration enhances cycle performance, reduces overvoltage, and improves electrochemical performance by blocking side reactions and suppressing lithium dendrite formation.

Implementation Method 1

a lithium nitride layer formed on at least one surface of the lithium metal layer... blocking side reactions caused by a direct contact between the lithium metal layer and an electrolyte

Methodology Applied

Scientific EffectPhysical barrier blocking:

Implementation Method 2

a carbon-based layer formed on the lithium nitride layer... increasing a specific surface area of a negative electrode

Methodology Applied

Scientific EffectSurface area enhancement:

Implementation Method 3

forming a lithium nitride film layer on at least one surface of a lithium metal layer... formed using methods like sputtering

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 4

formed using methods like sputtering or chemical vapor deposition

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS11127949B2Anode for lithium secondary battery, production method therefor, and lithium secondary battery comprising same

Publication Date: 2021.09.21 LG ENERGY SOLUTION LTD

AI summary

A negative electrode including a lithium metal layer, a lithium nitride thin film layer formed on at least one surface of the lithium metal layer, and a carbon-based thin film layer formed on the lithium nitride thin film layer, a method for preparing the same, and a lithium secondary battery including the same. A lithium nitride thin film layer and a carbon-based thin film layer formed on a lithium metal layer obtains current density distribution uniformly by blocking side reactions caused by a direct contact between the lithium metal layer and an electrolyte as well as increasing a specific surface area of a negative electrode, and enhances cycle performance and reduces an overvoltage by suppressing lithium dendrite formation to improve electrochemical performance of a lithium secondary battery.