Ion-Conductive Protective Layer for Lithium Anode

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Solution Overview

Problem

The consumption of electrolyte in lithium-based batteries during cycling due to reactions between metallic lithium and the electrolyte reduces the cycle life of electrochemical cells, necessitating the isolation of metallic lithium to prevent side reactions.

Innovation Solution

The use of an ion-conductive layer comprising fused inorganic particles, which allows lithium ions to diffuse while preventing electrolyte contact, thereby acting as a protective barrier to enhance the cycle life of lithium-based electrochemical cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If a lithium ion conductive material layer is coated on the surface of metallic lithium to prevent side reactions with electrolyte, then the cycle life of the cell is improved, but the device complexity increases

Engineering Contradiction:
Improvecycle lifeVSAvoidstructure complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent employs a porous coating layer made of lithium ion conductive material on the metallic lithium surface. The porous structure allows lithium ions to diffuse through while physically blocking electrolyte contact with the lithium metal, thereby extending cycle life without requiring a complete solid barrier that would increase complexity.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The invention uses composite structures combining metallic lithium with lithium ion conductive materials in a layered configuration. This composite approach enables the system to simultaneously achieve high ionic conductivity and electrolyte exclusion, resolving the contradiction between performance enhancement and structural simplicity.

Inventive Principle:
Principle #40Composite materials

2Reliability

If a protective layer is applied to isolate metallic lithium from electrolyte, then the reliability of the electrochemical cell is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveprotection effectivenessVSAvoidcoating uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The porous nature of the protective layer provides tolerance to manufacturing variations. The interconnected pore structure ensures continuous lithium ion transport pathways even if the coating thickness varies locally, maintaining reliability without requiring extremely precise coating control.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent allows the protective layer to have varying local properties, including thickness and porosity distribution. This local quality variation approach enables the coating to maintain overall protection effectiveness while accommodating manufacturing tolerances, as different regions can compensate for each other's deviations.

Inventive Principle:
Principle #3Local quality

3Reliability

If conventional protective structures are used for lithium electrodes, then some protection is achieved, but the cycle life and performance are still insufficient

Engineering Contradiction:
Improveprotection effectivenessVSAvoidcycle life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent specifically designs a porous protective layer with optimized porosity and pore size distribution. This porous structure provides superior lithium ion conductivity compared to conventional dense coatings, while simultaneously maintaining effective electrolyte exclusion, thereby achieving enhanced cycle life and performance.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The invention employs advanced composite material systems combining metallic lithium with specifically engineered lithium ion conductive materials. This composite structure achieves better interfacial compatibility and ion transport properties than conventional protective structures, resolving the insufficiency in cycle life and performance.

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 ion-conductive layer effectively prevents chemical reactions between polysulfides and the lithium anode, increasing sulfur utilization, reducing electrolyte depletion, and enhancing mechanical and chemical stability, leading to improved cycle life and performance in lithium-sulfur and lithium-ion batteries.

Implementation Method 1

This material allows lithium ions to diffuse to and from the metallic lithium surface while excluding the electrolyte from contacting the lithium surface

Methodology Applied
Scientific EffectIon diffusion: Diffusion

Implementation Method 2

The ion-conductive layer effectively prevents chemical reactions between polysulfides and the lithium anode

Methodology Applied
Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentEP3096376B1Protective layers for electrodes
Publication Date: 2019.03.20 BASF SE
  • EP3096376B1 patent drawingFigure 1A
  • EP3096376B1 patent drawingFigure 1B
  • EP3096376B1 patent drawingFigure 1C

AI summary

Articles and methods including layers for protection of electrodes in electrochemical cells are provided. As described herein, a layer, such as a protective layer for an electrode, may comprise a plurality of particles (e.g., crystalline inorganic particles, amorphous inorganic particles). In some aspects, at least a portion of the plurality of particles (e.g., inorganic particles) are fused to one another. For instance, in some aspects, the layer may be formed by aerosol deposition or another suitable process that involves subjecting the particles to a relatively high velocity such that fusion of particles occurs during deposition. In some aspects, the layer (e.g., the layer comprising a plurality of particles) is an ion-conducting layer.