Sulfide Solid Electrolyte Coating for Battery Interface Resistance

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Solution Overview

Problem

Current all-solid state secondary batteries face challenges in achieving high initial voltage and cycle characteristics due to issues with the formation of high-resistance layers at the interface between the positive electrode active material and sulfide-based inorganic solid electrolytes, which affect battery performance.

Innovation Solution

A solid electrolyte composition is developed, comprising a sulfide-based inorganic solid electrolyte, an active material coated with an ion-conductive oxide, and a polar dispersion medium, which improves dispersion stability and ion conductivity, thereby enhancing the initial voltage and cycle characteristics of the battery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sulfide-based inorganic solid electrolyte is used in all-solid state secondary batteries, then safety and reliability are significantly improved compared to organic electrolytic solutions, but a high-resistance layer forms at the interface with the positive electrode active material during operation, increasing battery resistance

Engineering Contradiction:

Improvesafety and reliabilityVSAvoidhigh-resistance layer formation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies an ion-conductive oxide coating layer as an intermediary between the positive electrode active material and the sulfide-based solid electrolyte. This intermediate layer prevents direct contact and reaction between the two materials, thereby suppressing the formation of high-resistance layers while maintaining good ion conductivity. The coating acts as a buffer that preserves the safety and reliability benefits of sulfide-based electrolytes without suffering from their interfacial degradation problems.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If powder compacting is used to form positive electrode active material layers with ion-conductive material coating, then the interface resistance issue is addressed, but the manufacturing process becomes more complex and time-consuming

Engineering Contradiction:

Improveinterface resistanceVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent pre-coats the positive electrode active material particles with ion-conductive oxide before electrode fabrication. This preliminary coating action ensures that the protective layer is already in place before the electrode assembly process, simplifying the overall manufacturing by eliminating the need for complex post-assembly treatments or specialized compacting procedures to achieve good interface contact.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If the positive electrode active material is coated with ion-conductive oxide and dispersed in solvent, then dispersion stability is improved, but additional manufacturing steps are required

Engineering Contradiction:

Improvedispersion stabilityVSAvoidmanufacturing simplicity

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent changes the surface properties of the positive electrode active material by coating with ion-conductive oxide, which improves wettability and dispersion stability. The coating modifies the surface energy and chemical properties of the particles, enabling better dispersion in the electrode slurry without requiring excessive additional processing steps.

Inventive Principle:

Principle #35Parameter changes

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 proposed solution results in an all-solid state secondary battery with improved initial voltage and cycle characteristics by maintaining ion conductivity and suppressing the formation of high-resistance layers, leading to better battery performance.

Implementation Method 1

an active material having a surface coated with an oxide having an ion conductivity

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a polar dispersion medium, in which the dispersion medium (C) includes a polar dispersion medium (C1)

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentUS11114689B2Solid electrolyte composition, solid electrolyte-containing sheet, all-solid state secondary battery, and methods for manufacturing solid electrolyte-containing sheet and all-solid state secondary battery

Publication Date: 2021.09.07 FUJIFILM CORP

AI summary

Provided are a solid electrolyte composition containing a sulfide-based inorganic solid electrolyte, an active material having a surface coated with an oxide having an ion conductivity, and a dispersion medium, in which the dispersion medium includes a specific polar dispersion medium, a solid electrolyte-containing sheet having a layer containing a sulfide-based inorganic solid electrolyte, an active material having a surface coated with an oxide having an ion conductivity, and a specific polar dispersion medium, an all-solid state secondary battery, and methods for manufacturing a solid electrolyte-containing sheet and an all-solid state secondary battery.