Solid Electrolyte Composition for Uniform All-Solid Battery Layers

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Solution Overview

Problem

All-solid state secondary batteries face challenges in achieving uniform thickness and excellent ion conductivity due to insufficient adhesiveness between solid particles, leading to defects like cracking, and variations in layer thickness affecting battery performance, especially in large-sized batteries.

Innovation Solution

A solid electrolyte composition comprising an inorganic solid electrolyte, a binder with specific ratios of precipitating and non-precipitating components, and a dispersion medium, which includes a polymer with a polyalkylene oxide chain and a nitrile group, is used to form a uniform layer with enhanced ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a binder formed of resin is added to improve binding properties between solid particles, then adhesiveness is improved, but ion conductivity decreases due to increased resistance

Engineering Contradiction:

ImproveadhesivenessVSAvoidion conductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the binder by incorporating specific functional groups (polyalkylene oxide chains and nitrile groups) in controlled ratios. This allows the binder to maintain both adhesiveness and ion conductivity by adjusting the molecular structure rather than simply changing material type or concentration.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite binder system combining organic resin with inorganic solid electrolyte particles. This composite structure allows the organic component to provide binding while the inorganic component maintains ion conductivity pathways, resolving the contradiction between adhesiveness and ion conductivity.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If solid particles are laminated under pressurization to increase energy density, then energy density is improved, but layer uniformity deteriorates causing thickness variation and cracking

Engineering Contradiction:

Improveenergy densityVSAvoidlayer uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The binder acts as an intermediary material between solid particles during lamination. It provides a matrix that holds particles together while accommodating pressurization forces, preventing direct particle-to-particle contact that would cause cracking and ensuring uniform thickness distribution across the layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention optimizes the ratio parameters of different binder components (polyalkylene oxide chain content and nitrile group content) to achieve the right balance between flexibility and structural integrity. This allows the layer to withstand pressurization while maintaining uniform thickness and preventing cracks.

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 composition achieves a uniform thickness and excellent ion conductivity, reducing defects and performance variations, making it suitable for large-sized batteries and improving safety and reliability.

Implementation Method 1

a binder (B), wherein the binder (B) includes a first binder (B1) that precipitates by a centrifugal separation process and a second binder (B2) that does not precipitate by the centrifugal separation process

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

an inorganic solid electrolyte (A) 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 3

a first binder (B1) that precipitates by a centrifugal separation process and a second binder (B2) that does not precipitate by the centrifugal separation process, the centrifugal separation process being performed in the dispersion medium (C) at a temperature of 25° C. at a centrifugal force of 610000 G for 1 hour

Methodology Applied

Scientific EffectCentrifugal separation: Centrifugal Separation

Data Source

PatentUS11552331B2Solid electrolyte composition, solid electrolyte-containing sheet, all-solid state secondary battery, method of manufacturing solid electrolyte-containing sheet, and method of manufacturing all-solid state secondary

Publication Date: 2023.01.10 FUJIFILM CORP

AI summary

A solid electrolyte composition includes: an inorganic solid electrolyte (A) having ion conductivity of a metal belonging to Group 1 or Group 2 in the periodic table; a binder (B); and a dispersion medium (C), in which the binder (B) includes a first binder (B1) that precipitates by a centrifugal separation process and a second binder (B2) that does not precipitate by the centrifugal separation process, the centrifugal separation process being performed in the dispersion medium (C) at a temperature of 25° C. at a centrifugal force of 610000 G for 1 hour, and a content X of the first binder (B1) and a content Y of the second binder (B2) satisfy the following expression,0.01≤Y/(X+Y)<0.10.