Gradient Sulfide Oxide Electrolyte for Copper Current Collector

Solution Overview

Problem

Sulfide solid-state batteries face issues with copper sulfide generation due to copper elution from the negative electrode current collector, leading to leak currents and reduced battery capacity, especially under high-temperature conditions or over-discharge states, and existing solutions either increase resistance or require complex multilayer structures.

Innovation Solution

Incorporating an oxide solid electrolyte material into the negative electrode mixture layer, with a higher concentration near the current collector to reduce copper sulfide generation and using a single-layer structure with a higher sulfide solid electrolyte material concentration further from the current collector, optimizing the ratio of sulfide to oxide materials and particle diameters to minimize resistance and maintain high-rate cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sulfide solid electrolyte material is used in the negative electrode mixture layer, then ionic conductivity is improved, but copper sulfide generation increases leading to reduced reliability

Engineering Contradiction:

Improveionic conductivityVSAvoidcopper sulfide generation

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating a gradient distribution of sulfide and oxide solid electrolyte materials within the negative electrode mixture layer. The sulfide solid electrolyte material concentration is higher near the positive electrode where high ionic conductivity is needed, while the oxide solid electrolyte material concentration is higher near the copper current collector where chemical stability is critical. This spatial variation in material composition allows simultaneous optimization of ionic conductivity and prevention of copper sulfide generation at different locations within the same layer.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining sulfide solid electrolyte material and oxide solid electrolyte material in a gradient distribution within the negative electrode mixture layer. The sulfide solid electrolyte material (e.g., Li2S-P2S5 system) provides high ionic conductivity, while the oxide solid electrolyte material (e.g., LLZO, LLTO) provides chemical stability against copper. The composite structure with controlled gradient composition enables the system to achieve both high ionic conductivity and resistance to copper sulfide formation.

Inventive Principle:

Principle #40Composite materials

2Reliability

If oxide solid electrolyte material is used to prevent copper sulfide generation, then reliability is improved, but resistance increases deteriorating high-rate cycle characteristics

Engineering Contradiction:

Improvecopper sulfide generation preventionVSAvoidhigh-rate cycle characteristics

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by creating a gradient distribution of sulfide and oxide solid electrolyte materials within the negative electrode mixture layer. The sulfide solid electrolyte material concentration is higher near the positive electrode where high ionic conductivity is needed, while the oxide solid electrolyte material concentration is higher near the copper current collector where chemical stability is critical. This spatial variation in material composition allows simultaneous optimization of ionic conductivity and prevention of copper sulfide generation at different locations within the same layer.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining sulfide solid electrolyte material and oxide solid electrolyte material in a gradient distribution within the negative electrode mixture layer. The sulfide solid electrolyte material (e.g., Li2S-P2S5 system) provides high ionic conductivity, while the oxide solid electrolyte material (e.g., LLZO, LLTO) provides chemical stability against copper. The composite structure with controlled gradient composition enables the system to achieve both high ionic conductivity and resistance to copper sulfide formation.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If uniform distribution of solid electrolyte materials is used, then manufacturing is simplified, but both copper sulfide generation and resistance cannot be simultaneously optimized

Engineering Contradiction:

Improvematerial distributionVSAvoidcopper sulfide generation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating a gradient distribution of sulfide and oxide solid electrolyte materials within the negative electrode mixture layer. The sulfide solid electrolyte material concentration is higher near the positive electrode where high ionic conductivity is needed, while the oxide solid electrolyte material concentration is higher near the copper current collector where chemical stability is critical. This spatial variation in material composition allows simultaneous optimization of ionic conductivity and prevention of copper sulfide generation at different locations within the same layer.

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

This configuration effectively inhibits copper sulfide formation, reduces resistance, and maintains high battery capacity even after repeated high-rate charge and discharge cycles, while simplifying the manufacturing process by eliminating the need for additional coatings and reducing costs.

Implementation Method 1

an oxide solid electrolyte material having high chemical stability instead of the sulfide solid electrolyte material from the viewpoint of preventing the generation of copper sulfide

Methodology Applied

Scientific EffectChemical stability:

Implementation Method 2

a sulfide solid electrolyte layer that contains the sulfide solid electrolyte material and is disposed between the negative electrode mixture layer and the positive electrode mixture layer

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 3

when Cu reacts with sulfur (S) of a sulfide solid electrolyte material in the negative electrode mixture layer, copper sulfide (e.g., Cu2S, CuS) may be generated

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS11476497B2Sulfide solid-state battery

Publication Date: 2022.10.18 TOYOTA JIDOSHA KK

AI summary

According to an aspect of the present invention, provided is a sulfide solid-state battery including a negative electrode current collector that contains copper, and a negative electrode mixture layer that contains a negative electrode active material, a sulfide solid electrolyte material, and an oxide solid electrolyte material. Assuming that the negative electrode mixture layer is virtually divided into two portions in a thickness direction, the upper layer portion contains a larger amount of the sulfide solid electrolyte material than the lower layer portion, and the lower layer portion contains a larger amount of the oxide solid electrolyte material than the upper layer portion.