All-Solid-State Battery Stack Bonding at Low Binding Pressure

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Solution Overview

Problem

All-solid-state batteries face a decrease in service capacity unless bound at high pressures of about 5 to 10 MPa, which requires large binding members and results in reduced energy density.

Innovation Solution

The battery is designed with a monopolar structure where two or more stacked battery units are bonded at a low binding pressure of 1.0 MPa or lower, using conductive carbon coating on the current collector layers and adhesive bonding between the active substance and current collector layers, allowing for effective contact even at lower pressures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high binding pressure (5 to 10 MPa) is applied to maintain service capacity, then service capacity is preserved, but binding members become large and energy density decreases

Engineering Contradiction:
Improveservice capacityVSAvoidenergy density
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The invention changes the binding pressure parameter from conventional high pressure (5-10 MPa) to low pressure (1.0 MPa or lower) by modifying the battery structure to include adhesive layers between stacked battery units, enabling effective bonding without requiring large binding members that would reduce energy density

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

An adhesive layer is introduced as an intermediary substance between the stacked battery units to enable effective bonding at low binding pressures. The adhesive compensates for the reduced mechanical pressure, maintaining service capacity without requiring large binding members

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If high binding pressure (5 to 10 MPa) is applied to maintain service capacity, then service capacity is preserved, but binding members become large and structure becomes complex

Engineering Contradiction:
Improveservice capacityVSAvoidbinding process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention changes the binding pressure parameter from high to low and simplifies the binding process by using adhesive layers during assembly, eliminating the need for complex post-assembly binding operations and large binding members

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The adhesive layers are applied in advance during the assembly process before stacking the battery units, enabling effective bonding without requiring subsequent high-pressure binding operations or large binding members

Inventive Principle:
Principle #10Preliminary action

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 design suppresses the decrease in service capacity even at low binding pressures, maintaining performance while simplifying the binding process and reducing the need for large binding members, thus preserving energy density.

Implementation Method 1

The first current collector layer and the first active substance layer that are stacked adjacently are bonded together with an adhesive

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

using conductive carbon coating on the current collector layers and adhesive bonding between the active substance and current collector layers, allowing for effective contact even at lower pressures

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3703168B1All-solid-state battery and method for manufacturing the same
Publication Date: 2023.12.13 TOYOTA JIDOSHA KK
  • EP3703168B1 patent drawingFigure 1
  • EP3703168B1 patent drawingFigure 2
  • EP3703168B1 patent drawingFigure 3

AI summary

An all-solid-state battery includes two or more stacked battery units (10, 11, 12) stacked together and having a monopolar structure. The stacked battery unit (10, 11, 12) includes a first current collector layer (1a, 3a, 5a), a first active substance layer (1b, 3b, 5b), a solid electrolyte layer (1c, 3c, 5c), a second active substance layer (1d, 3d, 5d), a second current collector layer (1e, 3e, 5e), a second active substance layer (2d, 4d, 6d), a solid electrolyte layer (2c, 4c, 6c), a first active substance layer (2b, 4b, 6b), and a first current collector layer (2a, 4a, 6a), which are stacked in this order. The first current collector layer (1a, 3a, 5a) and the first active substance layer (1b, 3b, 5b) that are stacked adjacently are bonded together with an adhesive.