Composite Active Material Sulfide Electrolyte Layer Optimization

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Solution Overview

Problem

Current solid-state batteries face limitations in achieving high battery output due to suboptimal ion and electron conducting paths, which are affected by the thickness and specific surface area of the sulfide solid electrolyte layer.

Innovation Solution

A composite active material is developed with a sulfide solid electrolyte layer having a specific surface area of 1.06 m2/g to 1.22 m2/g and a thickness of 15 nm to 25 nm, coated over an oxide active material and oxide solid electrolyte layer, produced using a compression shearing treatment under controlled conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sulfide solid electrolyte layer is made thicker to improve ion conductivity, then ion conductivity is improved, but electron conducting path may be broken and battery output decreases

Engineering Contradiction:

Improveion conductivityVSAvoidbattery output

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent optimizes the thickness parameter of the sulfide solid electrolyte layer to a specific range (10-30 nm) to simultaneously achieve sufficient ion conductivity and maintain electron conducting path integrity. This parameter optimization resolves the contradiction by finding the optimal thickness value that balances both requirements.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the specific surface area of the sulfide solid electrolyte layer is increased to improve contact area, then ion conductivity is improved, but the electron conducting path may be disrupted

Engineering Contradiction:

Improveion conductivityVSAvoidbattery output

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent optimizes the specific surface area parameter of the sulfide solid electrolyte layer to a specific range (0.5-2.0 m²/g) to achieve sufficient ion conductivity while maintaining electron conducting path continuity. This parameter control resolves the contradiction between contact area and electron path integrity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the coverage of the sulfide solid electrolyte layer is increased to improve ion conductivity, then ion conductivity is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveion conductivityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent optimizes the coverage parameter of the sulfide solid electrolyte layer to a specific range (70-95%) to achieve sufficient ion conductivity while avoiding excessive manufacturing complexity. This parameter optimization balances performance requirements with manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10122017B2Composite active material, solid battery and producing method for composite active material

Publication Date: 2018.11.06 TOYOTA JIDOSHA KK

AI summary

The main object of the present disclosure is to provide a composite active material with a capability of improving a battery output. The present disclosure achieves the object by providing a composite active material comprising: an oxide active material, an oxide solid electrolyte layer that coats a surface of the oxide active material, and a sulfide solid electrolyte layer that coats a surface of the oxide solid electrolyte layer; wherein the sulfide solid electrolyte layer has a specific surface area in a range of 1.06 m2/g to 1.22 m2/g, and a thickness the sulfide solid electrolyte layer is in a range of 15 nm to 25 nm.