Solid-State Battery Electrode Layout Against Li Dendrite Shorts

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Solution Overview

Problem

Solid-state batteries experience internal short-circuiting due to the contact between the negative electrode layer and the solid electrolyte layer, which is exacerbated by the expansion and contraction during charging, leading to Li dendrite deposition and stretching.

Innovation Solution

A solid-state battery design featuring a negative electrode layer, a protection layer, and a solid electrolyte layer with protruded portions that prevent direct contact between these layers, using different metal elements for alloying with lithium and ensuring the protection layer extends beyond the negative electrode layer and the solid electrolyte layer extends beyond the protection layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection layer is provided between the negative electrode layer and solid electrolyte layer to prevent contact, then the reliability is improved, but the protection layer may skirt to the positive electrode layer side during expansion and contraction, causing short-circuiting

Engineering Contradiction:

Improveprevention of contact between negative electrode and solid electrolyteVSAvoidshort-circuiting due to protection layer movement

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An insulating layer is introduced as an intermediary between the protection layer and the positive electrode layer. This insulating layer prevents direct contact between the protection layer (which may move during expansion/contraction) and the positive electrode layer, thereby eliminating the short-circuiting hazard while maintaining the protective function against negative electrode contact with the solid electrolyte.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the negative electrode layer is designed to expand during charging, then the alloying reaction with lithium is improved, but the negative electrode layer may extend to regions without protection layer coverage, causing Li dendrite deposition

Engineering Contradiction:

Improvealloying reaction efficiency with lithiumVSAvoidprevention of Li dendrite formation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The protection layer is designed to extend beyond the initial boundaries of the negative electrode layer in the discharged state. This preliminary extension ensures that when the negative electrode layer expands during charging, the protection layer is already in place to cover the extended regions and prevent Li dendrite formation at the interfaces with the solid electrolyte.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the protection layer completely covers the solid electrolyte layer, then the reliability is improved, but the device complexity and material consumption increase

Engineering Contradiction:

Improveinterface coverage between protection layer and solid electrolyteVSAvoidprotection layer configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protection layer is designed with spatially varying thickness and coverage: it extends beyond the negative electrode layer boundaries to provide preliminary coverage, and the insulating layer is applied selectively only in regions where the protection layer may contact the positive electrode layer during operation. This localized approach ensures reliability while minimizing unnecessary material consumption and device complexity.

Inventive Principle:

Principle #3Local quality

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

Inhibits internal short-circuiting by preventing direct contact between the negative electrode and solid electrolyte layers, enhancing cycle and rate characteristics by maintaining a reliable interface coverage with the protection layer.

Implementation Method 1

a first metal element M1 that is able to alloy with lithium; the protection layer includes a second metal element M2 that is able to alloy with lithium

Methodology Applied

Scientific EffectAlloying reaction:

Implementation Method 2

uses a deposition-dissolution reaction of metal lithium

Methodology Applied

Scientific EffectDeposition-dissolution reaction:

Implementation Method 3

the protection layer has a first protruded portion that is protruded outward beyond an end face of the negative electrode layer; the solid electrolyte layer has a second protruded portion that is protruded outward beyond an end face of the protection layer

Methodology Applied

Scientific EffectPhysical barrier effect: Physical Containment

Data Source

PatentUS20250372729A1Solid-state battery

Publication Date: 2025.12.04 TOYOTA JIDOSHA KK

AI summary

This disclosure provides a solid-state battery that has a negative electrode layer, a protection layer, a solid electrolyte layer, and a positive electrode layer in this order and uses a deposition-dissolution reaction of metal lithium. The negative electrode layer includes a first metal element that is able to alloy with lithium. The protection layer includes a second metal element that is able to alloy with lithium. The first and the second metal elements are different elements; and, as seen in a sectional view of the solid-state battery along a thickness direction, the protection layer has a first protruded portion that is protruded outward beyond an end face of the negative electrode layer in a direction orthogonal to the thickness direction, and the solid electrolyte layer has a second protruded portion that is protruded outward beyond an end face of the protection layer in the direction orthogonal to the thickness direction.