Solid-State Lithium-Ion Cell Protective Layer for Moisture-Stable Sintering

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Solution Overview

Problem

Lithium-ion batteries with solid-state electrolytes are unstable to atmospheric moisture and oxygen, requiring protective atmospheres and resulting in lithium evaporation during sintering, which reduces conductivity.

Innovation Solution

A method for producing lithium-ion batteries with a solid electrolyte that involves forming a protective layer with a lithium alloy base element to prevent moisture and oxygen exposure, and using a sintering process to create a solid electrolyte while maintaining lithium conductivity, eliminating the need for protective atmospheres and reducing lithium loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a solid-state electrolyte is used in lithium-ion batteries, then the energy density and safety are improved, but the stability against atmospheric moisture and oxygen deteriorates, requiring protective atmospheres during production

Engineering Contradiction:
Improveenergy densityVSAvoidstability against moisture and oxygen
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

A protective layer is introduced as an intermediary between the solid-state electrolyte and the atmosphere. This protective layer contains a base element for a lithium alloy that reacts with moisture and oxygen to form a stable protective oxide layer, thereby protecting the underlying solid-state electrolyte from atmospheric degradation without requiring a protective atmosphere during production

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective layer is applied in advance to the green body layer before sintering. This preliminary protective coating prevents moisture and oxygen from reaching the solid-state electrolyte during the sintering process and subsequent handling, eliminating the need for protective atmosphere facilities

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a protective atmosphere is used during sintering, then the stability of solid-state electrolyte is maintained, but the production complexity and cost increase

Engineering Contradiction:
Improvestability of solid-state electrolyteVSAvoidproduction complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protective layer serves as a mediator that eliminates the need for complex protective atmosphere facilities. By applying this layer before sintering, the solid-state electrolyte is protected from atmospheric degradation during production, simplifying the manufacturing process while maintaining product stability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The requirement for protective atmosphere facilities is extracted and removed from the production process. The protective layer enables sintering and handling to proceed in normal atmospheric conditions, eliminating the need for expensive and complex vacuum or inert gas systems

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If sintering is performed without a protective layer, then the production process is simplified, but lithium evaporates from the material reducing conductivity

Engineering Contradiction:
Improveproduction process simplicityVSAvoidlithium evaporation
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

The protective layer acts as a mediator that prevents lithium evaporation during sintering. The base element in the protective layer forms a stable oxide layer that acts as a barrier, preventing lithium from evaporating while allowing the sintering process to proceed without complex protective atmosphere facilities

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The base element in the protective layer, which would normally be considered an additional material step, actually benefits the process by forming a protective oxide layer that prevents lithium loss. The potential harm of added process steps is converted into the benefit of reduced lithium evaporation and simplified production

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 prevents lithium evaporation and maintains conductivity by forming a protective layer that converts into the negative electrode, allowing for stable and efficient production of lithium-ion batteries without the need for protective atmospheres during sintering.

Implementation Method 1

the green body layer is sintered so that the solid electrolyte is formed from the green body layer

Methodology Applied
Scientific EffectSintering: Sintering

Implementation Method 2

lithium is drawn from the solid electrolyte to the protective layer by means of an electrical voltage, thereby forming the lithium alloy from the base element and the lithium

Methodology Applied
Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentEP4372840A1Accumulator and method for producing an accumulator
Publication Date: 2024.05.22 VOLKSWAGEN AG
  • EP4372840A1 patent drawingFigure 1~2
  • EP4372840A1 patent drawingFigure 3~4
  • EP4372840A1 patent drawing

AI summary

The invention relates to a method for manufacturing a battery (2) which has at least one lithium-ion cell (4) in which a negative electrode (14), a positive electrode (12) and a solid electrolyte (10) are arranged, wherein an electrolyte suspension (28) is mixed to form the solid electrolyte (10) which has an electrolyte material, wherein a green body layer (30) is formed with the electrolyte suspension (28) and wherein a protective layer (26) is applied to the green body layer (30) which has a base element for a lithium alloy.