All-Solid Secondary Battery Buffering Polysulfide Side Reactions

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

All-solid secondary batteries face challenges with side reactions between polysulfide and lithium metal, disconnection of ion and electron transfer paths, and defects in the solid electrolyte layer leading to potential short circuits and reduced lifespan.

Innovation Solution

The battery design includes a lithium-containing sulfide-based positive electrode active material, a specific ratio of initial charge capacities for the negative and positive electrode layers, and an inactive member to prevent side reactions and disconnection of ion and electron transfer paths, while reducing defects in the solid electrolyte layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a sulfur-based material is used as a positive electrode active material to increase capacity, then the energy density is improved, but polysulfide is generated and moves to the negative electrode causing side reactions that degrade lifespan

Engineering Contradiction:

Improveenergy densityVSAvoidlifespan

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A buffer layer is introduced between the positive electrode active material layer and the solid electrolyte layer. This buffer layer acts as an intermediary that prevents polysulfide generated from the sulfur-based material from migrating to the negative electrode, thereby eliminating side reactions while maintaining high energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If the volume of the sulfur-based material is increased during initial discharging, then the capacity is improved, but the transfer path of ions and/or electrons in the electrode may be disconnected during the charging process

Engineering Contradiction:

ImprovecapacityVSAvoidtransfer path continuity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The buffer layer functions as a flexible thin film structure that can accommodate volume changes of the sulfur-based material during charging and discharging cycles. This flexible layer maintains continuous transfer paths for ions and electrons even when the active material expands or contracts, preventing disconnection while allowing high capacity operation

Inventive Principle:

Principle #30Flexible shells and thin films

3Ease of manufacture

If defects occur in the solid electrolyte layer during manufacturing or charging/discharging, then cracks may occur and grow, but lithium growth through cracks causes short circuits

Engineering Contradiction:

Improvemanufacturing processVSAvoidshort circuit prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The buffer layer serves as a preventive cushioning layer that compensates for defects and cracks in the solid electrolyte layer before lithium can grow through them. By providing this protective barrier in advance, the system prevents short circuits even when manufacturing defects or charging-induced cracks are present in the electrolyte layer

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

This design enhances the battery's cycle characteristics, prevents short circuits, and improves safety by suppressing side reactions and defects, leading to increased energy density and extended lifespan.

Implementation Method 1

a solid electrolyte layer between the positive electrode layer and the negative electrode layer

Methodology Applied

Scientific EffectPhysical barrier (solid electrolyte):

Implementation Method 2

because a volume of the sulfur-based material is increased during initial discharging, and the volume is decreased again during a charging process

Methodology Applied

Scientific EffectVolume expansion/contraction: Thermal Expansion

Implementation Method 3

a first inactive member on one surface of the positive electrode layer

Methodology Applied

Scientific EffectMechanical support/stress distribution:

Implementation Method 4

During a charging/discharging process of a secondary battery, polysulfide is generated from a sulfur-based material, and the generated polysulfide moves to (toward) a negative electrode and reacts with the negative electrode

Methodology Applied

Scientific EffectElectrochemical reaction:

Data Source

PatentUS20240079556A1All-solid secondary battery

Publication Date: 2024.03.07 SAMSUNG SDI CO LTD

AI summary

An all-solid secondary battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer includes a lithium-containing sulfide-based positive electrode active material, the lithium-containing sulfide-based positive electrode active material includes Li2S, a Li2S-containing composite, or a combination thereof, the all-solid secondary battery includes a first inactive member on one surface of the positive electrode layer, the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer, a ratio of initial charge capacity of the first negative electrode active material layer to initial charge capacity of the positive electrode active material layer is in a range of about 0.005 to about 0.45.