All-Solid-State Battery Separator With Segmented Binder Layers

Solution Overview

Problem

Conventional all-solid-state batteries face challenges in achieving both high ion conductivity and tensile strength due to the limitations of binder content in the solid electrolyte layer, which can lead to cracking or uneven distribution during production.

Innovation Solution

A separator for all-solid-state batteries is designed with a first solid electrolyte layer comprising a sulfide solid electrolyte and a hydrogenated rubber-based resin, where the resin content is between 15% to 30% by volume, and optionally a second solid electrolyte layer with a resin content of 0.1% to 15% by volume, enhancing both tensile strength and ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the binder content in the solid electrolyte layer is increased to improve tensile strength and prevent cracking, then the mechanical strength is improved, but the ion conductivity decreases due to reduced solid electrolyte content

Engineering Contradiction:

Improvetensile strengthVSAvoidion conductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The separator is divided into a first solid electrolyte layer and a second solid electrolyte layer with different binder contents. The first layer (15-30 vol% binder) provides high tensile strength to prevent cracking, while the second layer (0.1-15 vol% binder) provides high ion conductivity for battery performance. This segmentation allows each layer to optimize for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the separator have different binder concentrations optimized for their local functions. The first layer adjacent to electrodes has higher binder content for mechanical support and crack prevention, while the second layer has lower binder content for maximum ion conductivity. This local quality differentiation resolves the contradiction by assigning different material properties to different spatial locations.

Inventive Principle:

Principle #3Local quality

2Reliability

If the binder content is kept low to maintain high ion conductivity, then the ion conductivity is improved, but the tensile strength decreases leading to cracking during production and use

Engineering Contradiction:

Improveion conductivityVSAvoidtensile strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The separator is divided into a first solid electrolyte layer and a second solid electrolyte layer with different binder contents. The first layer (15-30 vol% binder) provides high tensile strength to prevent cracking, while the second layer (0.1-15 vol% binder) provides high ion conductivity for battery performance. This segmentation allows each layer to optimize for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the separator have different binder concentrations optimized for their local functions. The first layer adjacent to electrodes has higher binder content for mechanical support and crack prevention, while the second layer has lower binder content for maximum ion conductivity. This local quality differentiation resolves the contradiction by assigning different material properties to different spatial locations.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If a single-layer structure with uniform binder content is used, then the manufacturing process is simplified, but it is difficult to achieve both high tensile strength and high ion conductivity simultaneously

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidoverall performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The separator is divided into a first solid electrolyte layer and a second solid electrolyte layer with different binder contents. The first layer (15-30 vol% binder) provides high tensile strength to prevent cracking, while the second layer (0.1-15 vol% binder) provides high ion conductivity for battery performance. This segmentation allows each layer to optimize for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The separator uses a composite structure combining two different solid electrolyte layers with different binder concentrations. This composite material approach allows the system to exhibit both high mechanical strength (from the first layer) and high ion conductivity (from the second layer), achieving overall superior performance that neither single-layer configuration could provide alone.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11349176B2Separator for all-solid-state batteries, method for producing the same, and all-solid-state battery

Publication Date: 2022.05.31 TOYOTA JIDOSHA KK

AI summary

To provide a separator for all-solid-state batteries, which is configured to achieve both increased tensile strength and excellent ion conductivity, a method for producing the same, and an all-solid-state battery comprising the separator for all-solid-state batteries. Disclosed is a separator for all-solid-state batteries, the separator comprising a first solid electrolyte layer comprising a solid electrolyte and a hydrogenated rubber-based resin where a content of the hydrogenated rubber-based resin in the first solid electrolyte layer is 15% by volume or more and 30% by volume or less, and the separator optionally further comprising, on at least one surface of the first solid electrolyte layer, a second solid electrolyte layer comprising a solid electrolyte and a hydrogenated rubber-based resin where a content of the hydrogenated rubber-based resin in the second solid electrolyte layer is 0.1% by volume or more and less than 15% by volume.