Halogen-Modified Sulfide Electrolyte for Battery Cycle Life

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Solution Overview

Problem

Sulfide-based inorganic solid electrolytes used in all-solid state secondary batteries have high reactivity, leading to degradation in charging and discharging processes, which negatively impacts cycle characteristics and overall battery performance.

Innovation Solution

A solid electrolyte composition comprising a first sulfide-based inorganic solid electrolyte with a halogen element and a crystal phase, in contact with an active material, and a second sulfide-based inorganic solid electrolyte with a different composition, enhancing ion conductivity and reducing reactivity, is used to improve cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sulfide-based inorganic solid electrolyte is used, then ion conductivity is improved, but reactivity increases causing degradation and poor cycle characteristics

Engineering Contradiction:

Improvecycle characteristicsVSAvoidreactivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A surface-modified layer is introduced as an intermediary between the sulfide-based inorganic solid electrolyte and the active material. This surface layer acts as a protective barrier that reduces direct contact and chemical reactions between the highly reactive sulfide electrolyte and the active material, thereby suppressing degradation while preserving the high ion conductivity of the bulk electrolyte material.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface properties of the sulfide-based inorganic solid electrolyte are modified by changing its chemical composition or physical state at the surface. This surface modification alters the reactivity parameters of the electrolyte, reducing its tendency to react with active material while maintaining the bulk properties that provide high ion conductivity.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If sulfide-based inorganic solid electrolyte is used, then ion conductivity is improved, but degradation occurs during charging and discharging

Engineering Contradiction:

Improvebattery performanceVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The surface-modified layer serves as a protective intermediary that prevents direct degradation reactions between the sulfide electrolyte and active material during charging and discharging cycles. This intermediary layer maintains electrical and ionic contact while protecting both the electrolyte and active material from harmful chemical interactions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface modification is applied in advance to the sulfide-based inorganic solid electrolyte before assembly into the battery. This pre-applied protective layer cushions against degradation that would otherwise occur during subsequent charging and discharging operations, extending the service life of the battery.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 solid electrolyte composition significantly improves the cycle characteristics of all-solid state secondary batteries by reducing degradation and maintaining ion conductivity, leading to enhanced battery performance and extended service life.

Implementation Method 1

a first sulfide-based inorganic solid electrolyte which is in contact with the active material, contains a halogen element, and has a crystal phase at least in part

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

sulfide-based inorganic solid electrolytes have a high reactivity, deteriorate in the process of charging and discharging

Methodology Applied

Scientific EffectChemical stability:

Data Source

PatentUS10818967B2Solid electrolyte composition, electrode sheet for all-solid state secondary battery, all-solid state secondary battery, and methods for manufacturing electrode sheet for all-solid state secondary battery and all-solid state secondary battery

Publication Date: 2020.10.27 FUJIFILM CORP

AI summary

Provided are a solid electrolyte composition including an active material, a first sulfide-based inorganic solid electrolyte, and a second sulfide-based inorganic solid electrolyte having a composition different from that of the first sulfide-based inorganic solid electrolyte, in which the first sulfide-based inorganic solid electrolyte contains a halogen element and has a crystal phase at least in part, and the active material and the first sulfide-based inorganic solid electrolyte are in contact with each other, an electrode sheet for an all-solid state secondary battery and an all-solid state secondary battery for which the solid electrolyte composition is used, and methods for manufacturing an electrode sheet for an all-solid state secondary battery and an all-solid state secondary battery.