Solid Electrolyte Laminate Balancing Dendrite Blocking and Cycle Life

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Solution Overview

Problem

All-solid state secondary batteries face issues with internal short circuits due to dendrite growth and deterioration of cycle characteristics, which existing technologies have not adequately addressed, particularly in the context of lithium ion batteries where lithium dendrites are a significant concern.

Innovation Solution

A solid electrolyte laminated sheet with a multilayer structure is introduced, comprising a porous support with a high void ratio and a dense solid electrolyte layer with a lower void ratio, where the inorganic solid electrolyte particles are smaller than the porous support openings, and the layers are pressure-bonded to prevent dendrite penetration and stress propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a solid electrolyte layer with low void ratio is used to block dendrites, then reliability is improved, but cycle characteristics deteriorate due to volume change during charging and discharging

Engineering Contradiction:

Improvedendrite blocking capabilityVSAvoidcycle characteristics

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The solid electrolyte is divided into multiple layers with different void ratios. The first solid electrolyte layer (closer to negative electrode) has a higher void ratio to accommodate volume change, while the second solid electrolyte layer (closer to positive electrode) has a lower void ratio to block dendrites. This segmentation allows each layer to perform its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the solid electrolyte structure are assigned different properties. The first layer near the negative electrode is designed with higher porosity to handle metal precipitation and volume expansion, while the second layer near the positive electrode is designed with lower porosity to prevent dendrite penetration. This local differentiation optimizes both cycle stability and dendrite blocking.

Inventive Principle:

Principle #3Local quality

2Duration of action of moving object

If a porous support with high void ratio is used to accommodate metal precipitation, then cycle characteristics are improved, but reliability deteriorates due to dendrite penetration

Engineering Contradiction:

Improvecycle characteristicsVSAvoiddendrite blocking capability

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The electrolyte structure is segmented into multiple layers with progressively lower void ratios from the negative electrode side toward the positive electrode side. This gradient structure allows the first layers to accommodate volume change while subsequent layers progressively block dendrite growth.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solid electrolyte comprises a composite structure of multiple layers with different porosity characteristics. This composite design combines the advantages of high porosity (accommodating volume change) and low porosity (blocking dendrites) in a single integrated system.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If inorganic solid electrolyte particles smaller than porous support openings are used, then manufacturing ease is improved, but reliability worsens due to potential isolation of metal precipitation

Engineering Contradiction:

Improveparticle filling processVSAvoidmetal precipitation connectivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The solid electrolyte layers are designed with controlled porosity and interconnected pore structures that accommodate metal precipitation while maintaining connectivity. The porous structure allows metal to precipitate and remain connected to the electrode, preventing isolation even with small particles.

Inventive Principle:

Principle #31Porous materials

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 configuration effectively inhibits internal short circuits and enhances cycle characteristics by accommodating metal precipitation without isolation and blocking dendrite growth into the positive electrode, leading to improved safety and reliability of the battery.

Implementation Method 1

an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or Group 2 in the periodic table

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a sheet-shaped porous support which internally contains an inorganic solid electrolyte

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS20240006715A1Solid electrolyte laminated sheet, all-solid state secondary battery, and manufacturing method for all-solid state secondary battery

Publication Date: 2024.01.04 FUJIFILM CORP

AI summary

There is provided a solid electrolyte laminated sheet including a sheet-shaped porous support internally containing an inorganic solid electrolyte and a solid electrolyte layer internally containing an inorganic solid electrolyte, in which a void ratio of the porous support is 20% or more, and a void ratio of the solid electrolyte layer is smaller than the void ratio of the porous support. There are also provided a manufacturing method for an all-solid state secondary battery in which this solid electrolyte laminated sheet is used to carry out pressurization and manufacturing while adjusting void ratio of the porous support and the solid electrolyte layer, and an all-solid state secondary battery.