Solid Electrolyte Binder Composition for Low-Resistance Battery Interfaces

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Solution Overview

Problem

All-solid state secondary batteries face issues with low interface contact between solid particles and poor binding properties between solid particles and current collectors, leading to increased interface resistance and decreased battery performance, which is critical for high-performance applications like electric vehicles.

Innovation Solution

A solid electrolyte composition is developed using an inorganic solid electrolyte combined with binder particles formed from a specific branched resin, including a polymer chain with a Solubility Parameter (SP) value of 19.5 or higher and a macromonomer-derived component, enhancing the binding properties between solid particles and current collectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solid particles (inorganic solid electrolyte, active material) are used to form constituent layers, then the all-solid state secondary battery structure is achieved, but the interface contact between solid particles is low and interface resistance increases

Engineering Contradiction:

Improveinterface contact qualityVSAvoidinterface resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces binder particles as an intermediary substance between solid particles (inorganic solid electrolyte and active material). These binder particles improve interface contact quality by filling gaps and creating better physical contact between solid particles, thereby reducing interface resistance without compromising the all-solid state battery structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite material system combining solid particles (inorganic solid electrolyte and active material) with binder particles. This composite approach allows the binder particles to enhance the overall interface contact properties of the constituent layers, resolving the contradiction between maintaining solid-state structure and reducing interface resistance.

Inventive Principle:

Principle #40Composite materials

2Reliability

If binding properties of binder particles between solid particles are weak, then the structure is simpler, but poor contact between solid particles occurs

Engineering Contradiction:

Improvecontact between solid particlesVSAvoidbinding properties

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent modifies the binding properties parameter of the binder particles by selecting materials with appropriate adhesive characteristics. This parameter change ensures strong binding between binder particles and solid particles, preventing poor contact while maintaining structural integrity of the all-solid state battery layers.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If binding properties between solid particles and current collector are weak, then the manufacturing process is simpler, but poor contact between active material layer and solid electrolyte layer occurs due to expansion and contraction during charging and discharging

Engineering Contradiction:

Improvecontact between active material layer and solid electrolyte layerVSAvoidbinding properties between solid particles and current collector

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The binder particles serve as an intermediary layer between the solid particles (including active material and solid electrolyte) and the current collector. This intermediary binding system accommodates expansion and contraction during charging and discharging while maintaining consistent contact, preventing poor interface contact without requiring complex manufacturing processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If poor contact occurs between layers, then the device complexity is reduced, but the battery performance decreases

Engineering Contradiction:

Improvebattery performanceVSAvoidbinding structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a composite material approach where binder particles are combined with solid particles to form the constituent layers. This composite structure enhances battery performance by ensuring good contact between layers while avoiding excessive device complexity, as the binder particles are integrated directly into the layer formation process.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12142723B2Solid electrolyte composition, sheet for all-solid state secondary battery, electrode sheet for all-solid state secondary battery, all-solid state secondary battery, method of manufacturing sheet for all-solid state secondary battery, and method of manufacturing all-solid state secondary battery

Publication Date: 2024.11.12 FUJIFILM CORP

AI summary

Provided is a solid electrolyte composition including: an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or Group 2 in the periodic table; and binder particles including a resin represented by a specific formula. In addition, provided are a sheet for an all-solid state secondary battery, an electrode sheet for an all-solid state secondary battery, and an all-solid state secondary battery that include the above-described solid electrolyte composition, and a method of manufacturing the sheet for an all-solid state secondary battery and a method of manufacturing the all-solid state secondary battery.