Fluoride-Coated Active Material for Low-Resistance Solid-State Batteries

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Solution Overview

Problem

Conventional battery technologies face an increase in resistance during durability tests due to oxidative decomposition of solid electrolytes, particularly when using sulfide solid electrolytes with poor oxidation resistance, leading to inefficiencies and performance degradation.

Innovation Solution

A coated active material is developed with a fluoride-based solid electrolyte coating layer that has a low mass loss when dispersed, ensuring effective protection and reducing battery resistance by maintaining a favorable interface with other materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a sulfide solid electrolyte is used, then high ion conductivity is achieved, but oxidation resistance deteriorates leading to increased battery resistance during durability tests

Engineering Contradiction:

Improveion conductivityVSAvoidoxidation resistance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A coating layer comprising a fluoride solid electrolyte is applied to the surface of the active material particles. This coating layer acts as an intermediary protective barrier between the active material and the external environment, preventing oxidative decomposition while maintaining ion conductivity. The coating layer specifically targets and protects the surface where oxidation occurs, allowing the bulk sulfide solid electrolyte to maintain its high ion conductivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite structure where a fluoride-containing solid electrolyte coating is combined with the active material surface. This composite approach leverages the oxidation resistance of fluoride materials while preserving the high ion conductivity of the underlying sulfide solid electrolyte, achieving both properties simultaneously in a single system.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a coating layer is applied to protect the active material, then oxidation resistance is improved, but coating layer detachment increases leading to manufacturing difficulties

Engineering Contradiction:

Improveoxidation resistanceVSAvoidcoating layer stability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention optimizes the composition parameters of the coating layer by specifying that it must comprise a fluoride solid electrolyte with controlled content (1-50 mass% relative to active material). By adjusting these compositional parameters, the coating achieves optimal adhesion strength and mechanical stability, preventing detachment during electrode manufacturing processes while maintaining its protective function.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The coating layer is applied as a surface treatment specifically on the active material particles rather than as a bulk modification. This localized approach ensures that the protective properties are concentrated where needed (at the particle surface exposed to oxidation) while minimizing the overall amount of coating material, thereby reducing weight and improving adhesion through better interfacial contact.

Inventive Principle:

Principle #3Local quality

3Reliability

If the coating layer mass loss is reduced, then battery resistance increase is minimized, but manufacturing precision requirements increase

Engineering Contradiction:

Improveresistance stabilityVSAvoidcoating layer uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention specifies a coating layer content range of 1-50 mass% relative to the active material, allowing for some variation in coating thickness and distribution. This partial specification approach provides a practical manufacturing window that ensures sufficient protection (minimum 1% coating) while accommodating normal manufacturing tolerances, avoiding overly stringent precision requirements that would complicate production.

Inventive Principle:

Principle #16Partial or excessive 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

The coated active material significantly reduces battery resistance and improves durability by minimizing coating layer loss and enhancing ion conductivity, thereby maintaining efficient charge and discharge performance.

Implementation Method 1

oxidative decomposition of the solid electrolyte can occur during charging of a battery. This tendency is notable when the solid electrolyte is one having a poor oxidation resistance, such as a sulfide solid electrolyte

Methodology Applied

Scientific EffectOxidation resistance: Oxidation

Implementation Method 2

enhancing ion conductivity, thereby maintaining efficient charge and discharge performance

Methodology Applied

Scientific EffectIon conductivity: Conduction (electrical)

Data Source

PatentUS20250105281A1Coated active material, electrode material, battery, and battery manufacturing method

Publication Date: 2025.03.27 PANASONIC HOLDINGS CORP

AI summary

A coated active material of the present disclosure includes: an active material; and a coating layer including a first solid electrolyte and coating at least a portion of a surface of the active material, wherein the first solid electrolyte includes a fluoride, and a mass of the coating layer that falls off the active material by dispersing the coated active material in an organic dispersion medium is less than 42% of a total mass of the coating layer.