Sulfide Solid Electrolyte Composition for Stable All-Solid Batteries

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Solution Overview

Problem

Current sulfide-based solid electrolytes for all-solid secondary batteries face challenges in achieving high crystallinity without high-temperature heat treatment and maintaining stability with lithium metal, leading to instability and side reactions during charge and discharge.

Innovation Solution

A sulfide-based solid electrolyte composition including an ionic conductor with PS43−, P2S64−, and P2S74− units, along with a lithium compound containing a halogen element, is developed, which can be prepared at lower temperatures and exhibits improved stability and ionic conductivity when used in all-solid secondary batteries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If high-temperature heat treatment (500°C or greater) is applied to achieve high crystallinity, then crystallinity is improved, but compositional stability deteriorates

Engineering Contradiction:

ImprovecrystallinityVSAvoidcompositional stability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the temperature parameter from high-temperature (500°C or greater) to low-temperature (350°C or less) heat treatment, and adjusts the composition parameters (molar ratios of P2S6 4- to PS4 3- units from 1:4 to 1:1, and P2S7 4- unit content to 60% or less) to achieve both crystallinity and compositional stability simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite solid electrolyte membrane containing both crystalline regions (providing stability) and amorphous regions (providing ionic conductivity), achieved by controlling the heat treatment temperature and composition to form a mixed-phase structure

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If amorphous sulfide-based solid electrolyte is prepared using low heat treatment temperature (350°C or less), then manufacturing complexity is reduced, but stability with lithium metal deteriorates

Engineering Contradiction:

Improveheat treatment temperatureVSAvoidstability with lithium metal

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the heat treatment temperature parameter to 350°C or less (reducing manufacturing complexity) while simultaneously adjusting the composition parameters (molar ratios and P2S7 4- unit content) to maintain stability with lithium metal, resolving the contradiction between ease of manufacture and reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent forms a composite structure with both crystalline and amorphous phases, where the crystalline regions provide stability with lithium metal while the amorphous regions maintain ionic conductivity, achieving both ease of manufacture and reliability

Inventive Principle:

Principle #40Composite materials

3Device complexity

If amorphous sulfide-based solid electrolyte is used, then manufacturing complexity is reduced, but reactivity with lithium metal increases causing side reactions

Engineering Contradiction:

Improvecrystallinity requirementVSAvoidside reactions with lithium metal

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the composition parameters (molar ratios of P2S6 4- to PS4 3- units to 1:1 to 5:1, and P2S7 4- unit content to 60% or less) to reduce reactivity with lithium metal while maintaining the amorphous structure, thereby reducing device complexity and eliminating harmful side reactions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the typically harmful amorphous structure (which causes high reactivity) into a beneficial configuration by optimizing the composition ratios, where the amorphous structure now provides good ionic conductivity without the harmful side reactions, turning a disadvantage into an advantage

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 novel sulfide-based solid electrolyte enhances the cycle characteristics of all-solid secondary batteries by suppressing side reactions with lithium metal and maintaining high ionic conductivity, thereby improving the battery's performance and safety.

Implementation Method 1

an ionic conductor including a PS43− unit, a P2S64− unit, and a P2S74− unit

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

improved stability with respect to lithium metal

Methodology Applied

Scientific EffectChemical stability:

Data Source

PatentUS11682790B2Sulfide-based solid electrolyte, all-solid secondary battery including the same, and method of preparing the sulfide-based solid electrolyte

Publication Date: 2023.06.20 SAMSUNG ELECTRONICS CO LTD

AI summary

A sulfide solid electrolyte includes: an ionic conductor including a PS43− unit, a P2S64− unit, and a P2S74− unit; and a lithium compound containing a halogen element, wherein a molar ratio of the P2S64− unit to the PS43− unit is about 1:1 to about 5:1, and a molar amount of the P2S74− unit with respect to the total molar amount of the PS43− unit, the P2S64− unit, and the P2S74− unit is greater than 0 to about 60%.