All-Solid-State Battery Electrode Layout to Suppress Edge Dendrites

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Solution Overview

Problem

All-solid-state secondary batteries face durability issues due to the inward shifting of active material layers, leading to lithium dendrite formation and potential internal short circuits, which reduces charge-discharge capacity over cycles.

Innovation Solution

The battery design includes a positive electrode collector layer with an insulating layer around the perimeter edges of the active material layer, ensuring the outer edges of the collector layer are inward from the active material layer, thereby reducing lithium ion concentration and inhibiting dendrite formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the active material layer is formed by coating and drying slurry onto a transfer substrate and then transferred onto the solid electrolyte layer, then the active material layer can be efficiently formed, but the outer edges of the active material layer are rounded due to surface tension and shifted inward from the outer edges on the current collector layer side

Engineering Contradiction:

Improveease of forming active material layerVSAvoidpositioning precision of active material layer edges

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by forming the insulating layer on the current collector layer before transferring the active material layer. This pre-formed insulating layer serves as a boundary that prevents the active material from spreading beyond desired edges during the transfer process, thereby compensating for the inward shifting caused by surface tension effects in the slurry coating method.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the outer edges of the positive electrode active material layer on the solid electrolyte layer side are shifted inward from the outer edges on the current collector layer side, then the active material layer formation is simplified, but lithium dendrites form at the outer edges and potential internal short circuits occur, reducing durability

Engineering Contradiction:

Improveease of active material layer formationVSAvoiddurability against lithium dendrite formation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent converts the harmful inward-shifting effect caused by surface tension into a beneficial feature by designing the insulating layer to extend beyond the active material layer edges. The shifted edges now align with the insulating layer boundaries, preventing lithium dendrite formation at the problematic interface between active material and solid electrolyte, while the insulating material itself acts as a physical barrier against dendrite penetration.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If an insulating layer is disposed around the perimeter edges of the positive electrode active material layer and the outer edges of the collector layer are positioned inward from the active material layer, then lithium dendrite formation is inhibited, but the device structure becomes more complex

Engineering Contradiction:

Improvedurability against lithium dendrite formationVSAvoidstructural complexity of electrode layers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The insulating layer serves multiple functions simultaneously: it acts as a boundary during the transfer process to define active material edges, provides a physical barrier to prevent lithium dendrite formation and penetration, and serves as an electrical insulator. By combining these functions into a single layer, the patent avoids the need for separate structural elements, thereby limiting the increase in device complexity while achieving enhanced reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 durability of the battery by preventing lithium dendrite growth, maintaining high charge-discharge capacity over repeated cycles and reducing the risk of internal short circuits.

Implementation Method 1

a positive electrode layer having a positive electrode active material layer and an insulating layer disposed around perimeter edges of the positive electrode active material layer

Methodology Applied

Scientific EffectPhysical barrier (insulating layer):

Implementation Method 2

all-solid-state secondary batteries in which the electrolyte solution is replaced with solid electrolyte powder

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS11961973B2All-solid-state secondary battery

Publication Date: 2024.04.16 TOYOTA JIDOSHA KK

AI summary

The all-solid-state secondary battery of the disclosure comprises a positive electrode collector layer, a positive electrode layer, a solid electrolyte layer, a negative electrode layer and a negative electrode collector layer stacked in that order, wherein the positive electrode layer has a positive electrode active material layer and an insulating layer disposed around the perimeter edges of the positive electrode active material layer, and when the all-solid-state secondary battery is viewed from the stacking direction, the outer edges of the positive electrode active material layer on the solid electrolyte layer side are further inward than the outer edges of the positive electrode active material layer on the positive electrode collector layer side, and the outer edges of the positive electrode collector layer are further inward than the outer edges of the positive electrode active material layer on the positive electrode collector layer side.