Lithium Foil Electrode Assembly With Diffusion-Bonded Collector Interface

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Solution Overview

Problem

Lithium metal in lithium-ion batteries does not readily adhere to common current collector materials, leading to delamination and potential premature electrochemical cell failure, which diminishes performance.

Innovation Solution

The development of electrode assemblies with nano-scale solid solution interfaces that chemically bind current collectors and lithium metal foils, achieved through heating a precursor assembly to allow lithium atoms to diffuse into the current collector, forming a solid solution interface that enhances adhesion and electrical contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal is used in the negative electrode to achieve high theoretical capacity and lowest electrochemical potential, then energy storage performance is improved, but adhesion to current collector deteriorates leading to delamination and cell failure

Engineering Contradiction:

Improveenergy storage capacityVSAvoidadhesion stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A diffusion barrier layer is introduced as an intermediary between the lithium metal foil and the current collector. This barrier layer prevents direct contact while allowing lithium ion transport, thereby maintaining the high capacity benefits of lithium metal while preventing delamination and improving adhesion stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrode structure is designed as a composite system comprising lithium metal foil, a diffusion barrier layer with specific composition and structure, and current collector. This composite approach combines the high capacity of lithium metal with the adhesion properties of the barrier layer, resolving the contradiction between energy storage and reliability.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If physical or mechanical techniques are used to attach lithium metal to current collector, then attachment is achieved, but delamination occurs and performance diminishes

Engineering Contradiction:

Improveattachment processVSAvoidbond stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The mechanical attachment techniques are replaced with a chemical/diffusion-based approach. The diffusion barrier layer enables lithium atoms to diffuse into the current collector, creating a metallurgical bond that is superior to mechanical attachment methods in terms of stability and reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If lithium metal foil is directly placed on current collector to simplify structure, then device complexity is reduced, but delamination and premature failure occur

Engineering Contradiction:

Improveelectrode structureVSAvoidcell performance stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Rather than uniformly complicating the entire electrode structure, the diffusion barrier layer is applied locally at the critical interface between lithium metal and current collector. This targeted approach provides the necessary adhesion improvement only where delamination occurs, minimizing overall structural complexity while maximizing reliability.

Inventive Principle:

Principle #3Local quality

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 approach improves the adhesion and electrical contact between the lithium metal foil and the current collector, leading to enhanced performance and stability of lithium-ion batteries by creating a stable chemical bond, thereby preventing delamination and extending the battery's lifespan.

Implementation Method 1

heating a precursor electrode assembly that includes a current collector and a lithium metal film disposed on one or more surfaces of the current collector to a temperature that is less than a melting point of lithium, so that lithium atoms from the lithium metal film diffuse into the current collector during the heating forming a solid solution interface

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20240047693A1Electrode assemblies prepared using diffusion coupling

Publication Date: 2024.02.08 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

An electrode assembly that includes a current collector, a lithium foil, and a solid solution interface that chemically binds the current collector and the lithium foil is provided. The solid solution interface includes a portion of the current collector that is impregnated with lithium atoms diffused from the lithium foil. In some variations, a method for forming the electrode assembly includes heating a precursor electrode assembly that includes a current collector and a lithium metal film to a temperature that is less than a melting point of lithium, so that lithium atoms diffuse into the current collector during the heating. In other variations, a method for forming the electrode assembly includes disposing a molten lithium onto a heated current collector to form a precursor electrode assembly, and cooling the assembly to form a lithium metal layer that is chemically bonded to the current collector.