Solid Electrolyte Battery Anode Structure for Stable Interface Adhesion

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Solution Overview

Problem

In solid electrolyte batteries using graphite as the negative electrode active material, the mechanical strength at the interface with the bonded solid electrolyte layer decreases due to repeated expansion and contraction during charging and discharging, leading to micro void generation and decreased homogeneous reactivity, which results in increased battery resistance and reduced durability.

Innovation Solution

A solid electrolyte battery configuration is introduced, featuring a first negative electrode layer with crystalline carbon and a second negative electrode layer with amorphous carbon, both mixed with a negative electrode layer solid electrolyte. The average particle size of the negative electrode layer solid electrolyte is smaller than that of the amorphous carbon, which is in turn smaller than that of the crystalline carbon, enhancing adhesion and suppressing resistance increases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If graphite is used as the negative electrode active material to achieve high capacity, then the discharge capacity per unit weight or unit volume increases, but the mechanical strength at the interface with the solid electrolyte layer decreases due to repeated expansion and contraction, leading to micro void generation and reduced homogeneous reactivity

Engineering Contradiction:

Improvedischarge capacityVSAvoidinterface mechanical strength

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a composite structure combining crystalline carbon (graphite) and amorphous carbon in the negative electrode. The crystalline carbon provides high capacity, while the amorphous carbon acts as a buffer to suppress expansion and contraction, maintaining interface mechanical strength and preventing micro void generation during charge-discharge cycles.

Inventive Principle:

Principle #40Composite materials

2Reliability

If high confining pressure is applied to maintain adhesion between electrode layers and solid electrolyte, then homogeneous reactivity is maintained, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvehomogeneous reactivityVSAvoidconfining pressure mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent designs the negative electrode composite structure to self-maintain adhesion with the solid electrolyte layer through the amorphous carbon component that suppresses volume changes. This eliminates the need for complex external confining pressure mechanisms, as the structure itself prevents micro void formation and maintains homogeneous reactivity during cycling.

Inventive Principle:

Principle #25Self-service

3Device complexity

If the negative electrode structure is simplified to reduce manufacturing complexity, then the device complexity decreases, but the adhesion between electrode layers deteriorates and resistance increases

Engineering Contradiction:

Improvenegative electrode structureVSAvoidadhesion between layers

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent employs a composite material approach using both crystalline and amorphous carbon in the negative electrode. This composite structure inherently provides both good adhesion to the solid electrolyte layer and suppression of expansion-contraction movements, maintaining reliable electrical contact without requiring complex multi-layer structures or additional adhesion-promoting components.

Inventive Principle:

Principle #40Composite 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 suppresses the increase in battery resistance after charge-discharge cycles, improves adhesion between electrode layers, and enhances the durability of the battery, while also reducing the need for high confining pressures during charging and discharging.

Implementation Method 1

repeated expansion and contraction of the graphite during charging and discharging

Methodology Applied

Scientific EffectExpansion and contraction of crystalline carbon: Thermal Expansion

Implementation Method 2

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

Methodology Applied

Scientific EffectIon conduction: Fast Ion Conductor

Data Source

PatentUS20250038253A1Solid electrolyte battery and method for producing solid electrolyte battery

Publication Date: 2025.01.30 VEHICLE ENERGY JAPAN INC

AI summary

A solid electrolyte battery comprises a positive electrode layer, a negative electrode layer and a solid electrolyte layer formed between the positive electrode layer and the negative electrode layer, and which is characterized in that: the negative electrode layer comprises a first negative electrode layer, and a second negative electrode layer that is superposed on the first negative electrode layer so as to be in contact with the solid electrolyte layer; the active material of the first negative electrode layer is a crystalline carbon; the active material of the second negative electrode layer is an amorphous carbon; a negative electrode layer solid electrolyte is mixed into the first negative electrode layer and the second negative electrode layer; and (average particle size (D50) of negative electrode layer solid electrolyte 32)<(average particle size (D50) of crystalline carbon 2)<(average particle size (D50) of amorphous carbon 1) is satisfied.