Solid-State Battery Layer Structure with Polymer Protective Coating

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Solution Overview

Problem

Current lithium-ion solid-state batteries face challenges in large-scale production, high energy density, and dendrite growth, which leads to short circuits, and the use of expensive lithium-indium alloys and graphite-based anodes results in lower energy density and increased manufacturing costs.

Innovation Solution

A method for producing a layered structure for lithium-ion solid-state batteries involving the application of a cathode composite material, a sulfidic electrolyte layer, an electrolyte protective layer, and an anode layer with elemental lithium, which suppresses dendrite growth and allows for scalable production with adjustable layer thicknesses, reducing the need for expensive alloys and graphite-based anodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sulfidic electrolytes are used in combination with lithium metal, then high electrical conductivity at room temperature is achieved, but intrinsic instability at low potentials occurs leading to dendrite growth

Engineering Contradiction:
Improveelectrical conductivityVSAvoiddendrite growth
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A protective layer comprising a polymer conductive to lithium ions is introduced as an intermediary between the sulfidic electrolyte and lithium metal anode. The polymer layer (containing functional groups such as -SO3Li, -COOLi, or -OLi) serves as a mediator that prevents direct contact between the sulfidic electrolyte and lithium metal, thereby suppressing dendrite growth while maintaining ionic conductivity for lithium ion transport.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If lithium-indium alloys or graphite-based anodes are used, then manufacturing is simplified, but energy density and specific energy are reduced

Engineering Contradiction:
Improveanode productionVSAvoidenergy density
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent employs a protective polymer layer that can be applied as a thin film on the lithium metal anode surface. This disposable-like protective coating prevents dendrite growth and electrolyte degradation without requiring expensive alloying elements like indium or complex composite structures with graphite, thereby maintaining high energy density while simplifying manufacturing.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If solid-state accumulators are produced as pellets on laboratory scale, then dendrite growth can be suppressed, but large-scale production is not enabled and energy density is limited due to greater electrolyte layer thickness

Engineering Contradiction:
Improvedendrite suppressionVSAvoidlarge-scale production capability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent changes the critical parameter of electrolyte layer thickness by introducing a protective polymer layer that enables the use of much thinner sulfidic electrolyte layers (5-50 μm) compared to conventional pellet production (hundreds of micrometers). This parameter change allows transition from laboratory-scale pellet production to large-scale manufacturing while maintaining dendrite suppression and achieving high energy density.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If protective layers comprising polymers conductive to lithium ions are applied, then dendrite growth is suppressed and intrinsic stability is enhanced, but manufacturing complexity increases

Engineering Contradiction:
Improveintrinsic stabilityVSAvoidlayer structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protective polymer layer is applied locally only at the critical interface between the sulfidic electrolyte and lithium metal anode where dendrite growth occurs. This localized application approach enhances stability at the specific problem area without requiring complex modifications throughout the entire battery structure, thereby limiting the increase in manufacturing complexity.

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

The method efficiently suppresses dendrite growth, enhances the intrinsic stability of sulfidic electrolytes, enables high specific energy and energy density, and reduces manufacturing costs by allowing large-scale production with adjustable layer thicknesses, thus improving the safety, stability, and environmental friendliness of lithium-ion solid-state batteries.

Implementation Method 1

sulfidic electrolyte layer...exhibit high electrical conductivity at room temperature

Methodology Applied
Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

anode layer with elemental lithium, which suppresses dendrite growth

Methodology Applied
Scientific EffectDendrite growth suppression:

Implementation Method 3

lithium-ion solid-state rechargeable battery...store and provide electrical energy

Methodology Applied
Scientific EffectElectrochemical energy conversion: Battery (electricity)

Data Source

PatentEP3553867A1Method for producing a layer structure for a lithium-ion solid body battery
Publication Date: 2019.10.16 KARLSRUHER INST FUR TECH
  • EP3553867A1 patent drawingFigure 1
  • EP3553867A1 patent drawingFigure 2a~2b
  • EP3553867A1 patent drawingFigure 2c

AI summary

A method for producing a layered structure (110) for a lithium-ion solid-state battery (108) is proposed. Furthermore, a lithium-ion solid-state battery (108) and its use are proposed.The method comprises the following steps: a) providing a dispersion of a cathode composite material; b) applying the dispersion of the cathode composite material to a substrate (120) such that at least one cathode layer (118) is formed on at least one substrate surface (122) of the substrate (120); c) applying a sulfide electrolyte layer (116) to at least one cathode surface (124) of the cathode layer (118) opposite the substrate surface (122); d) applying an electrolyte protective layer (114) to at least one electrolyte surface (126) opposite the cathode surface (124); and e) applying an anode layer (112) to at least one electrolyte protective layer surface (128) opposite the electrolyte surface (126), thereby forming the layer structure (110), wherein the anode layer (112) comprises elemental lithium.