Lithium Diffusion Rate-Controling Layer for Negative Electrode

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium metal oxides used in negative electrodes for lithium ion batteries undergo volume changes during charge/discharge, leading to cracking and degradation, and existing pre-lithiation methods can result in non-homogeneous lithium diffusion and loss of lithium content.

Innovation Solution

A novel pre-lithiation method involving a lithium diffusion rate-controlling layer with a polymer material, such as a swellable or elutable polymer, is introduced between the lithium foil and the negative electrode active material layer to control lithium diffusion and prevent loss, improving cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium metal foil is laminated on the surface of negative electrode active material and electrolyte is injected, then lithium diffusion into negative electrode active material layer occurs, but lithium diffusion becomes non-homogeneous and resistance increases when electrolyte injection is delayed

Engineering Contradiction:

Improvecycle lifeVSAvoidlithium diffusion uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

A lithium diffusion rate-controlling layer is introduced as an intermediary between the lithium metal foil and the negative electrode active material layer. This layer controls the diffusion rate of lithium, ensuring homogeneous diffusion into the active material while preventing lithium loss to the air, thereby resolving the contradiction between reliability improvement through pre-lithiation and manufacturing precision maintenance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If lithium metal foil is laminated on negative electrode active material, then pre-lithiation occurs, but lithium content is lost when diffusion to air occurs

Engineering Contradiction:

Improvecycle lifeVSAvoidlithium content

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The lithium diffusion rate-controlling layer serves as a protective intermediary that prevents direct exposure of lithium metal to air, thereby preventing lithium content loss while still allowing controlled diffusion into the negative electrode active material layer to achieve pre-lithiation and improve cycle life.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin film lithium diffusion rate-controlling layer is used to encapsulate the lithium metal foil, providing protection against air exposure while maintaining flexibility for lithium ion diffusion. This thin film structure prevents lithium content loss without compromising the pre-lithiation function.

Inventive Principle:

Principle #30Flexible shells and thin films

3Quantity of substance

If metal oxide is used as negative electrode active material, then high theoretical capacity is achieved, but volume change during charge/discharge causes cracking and deterioration

Engineering Contradiction:

ImprovecapacityVSAvoidstructural integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The lithium diffusion rate-controlling layer acts as a cushioning layer that accommodates the volume changes of the metal oxide during charge/discharge cycles. This beforehand cushioning prevents cracking and deterioration of the active material structure, maintaining structural integrity while preserving the high capacity benefit.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

A composite structure is created by combining the metal oxide active material with the lithium diffusion rate-controlling layer. This composite material structure provides both the high capacity of metal oxide and the structural stability needed to prevent cracking during volume changes.

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 method ensures homogeneous lithiation, inhibits lithium loss and side reactions, and enhances the cycle life of lithium ion batteries by controlling lithium diffusion and maintaining lithium content.

Implementation Method 1

a lithium diffusion rate-controlling layer formed on the surface of the electrode active material layer... the lithium diffusion rate-controlling layer includes a polymer material

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

the polymer material includes a swellable polymer material... the swellable polymer material shows a swelling degree

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS11450855B2Negative electrode for lithium secondary battery and lithium ion secondary battery including the same

Publication Date: 2022.09.20 LG ENERGY SOLUTION LTD

AI summary

An electrode including a lithium diffusion rate-controlling layer and a lithium layer stacked successively on the surface thereof, and a method for manufacturing the same are disclosed. The electrode includes: a current collector; an electrode active material layer formed on the surface of the current collector; a lithium diffusion rate-controlling layer formed on the surface of the electrode active material layer; and a lithium layer containing a lithium metal ingredient and formed on the surface of the lithium diffusion rate-controlling layer.