Multi-Layer Solid Electrolyte Separator Against Lithium Dendrites

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Solution Overview

Problem

Rechargeable lithium metal batteries face issues with lithium metal dendrite formation leading to internal short circuits and thermal runaway, and the reactions between lithium metal and electrolyte result in capacity decay, which have not been adequately addressed by existing complex and costly solutions.

Innovation Solution

A flame-resistant composite separator with multiple layers, including a first layer of sintered inorganic solid electrolyte or polymer composite and a second layer with dispersed lithium salt, enhances lithium-ion conductivity and prevents dendrite penetration, while maintaining a stable contact with the anode and cathode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal is used as anode active material to achieve high capacity, then energy density is improved, but dendrite formation occurs leading to safety issues

Engineering Contradiction:

Improveenergy densityVSAvoidsafety

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A protective layer comprising a polymer matrix with lithium ion-conducting inorganic particles is introduced as an intermediary between the lithium metal anode and the electrolyte. This protective layer acts as a mediator that allows lithium ion transport while preventing direct contact between lithium metal and electrolyte, thereby eliminating dendrite formation and improving safety while maintaining high energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If complex multi-layer anode structures are used to prevent dendrite formation, then safety is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

ImprovesafetyVSAvoidanode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective layer integrates multiple functions into a single composite structure: the polymer matrix provides mechanical flexibility and ion conductivity, while embedded lithium ion-conducting inorganic particles enhance ion transport pathways. This merged structure eliminates the need for separate protective layers and complex multi-layer configurations, reducing device complexity while maintaining safety

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The protective layer is constructed as a composite material system combining organic polymer matrix with inorganic lithium ion-conducting particles. This composite approach leverages the advantages of both materials - the flexibility and processability of polymers with the high ion conductivity of inorganic particles - achieving effective dendrite prevention with a relatively simple single-layer structure

Inventive Principle:

Principle #40Composite materials

3Use of energy by moving object

If lithium metal anode is used to achieve high capacity, then energy density is improved, but capacity decay occurs due to reactions with electrolyte

Engineering Contradiction:

Improveenergy densityVSAvoidcycle life

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of stationary object

Solution Approach 1:

The protective layer serves as a stable intermediary barrier between lithium metal and electrolyte, preventing direct harmful reactions. This mediator allows beneficial lithium ion transport while blocking detrimental chemical reactions, thereby maintaining high capacity and extending cycle life without sacrificing energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

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 composite separator improves safety and cycle life by preventing dendrite-induced failures and reducing detrimental reactions, maintaining high specific capacity and energy density in lithium metal batteries.

Implementation Method 1

a first layer of inorganic solid electrolyte or a first layer of polymer composite

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

a first layer of sintered inorganic solid electrolyte or a first layer of polymer composite comprising 60%-99% by volume of inorganic material particles

Methodology Applied

Scientific EffectPhysical barrier effect: Physical Containment

Implementation Method 3

a second layer that comprises a second polymer and from 0.1% to 50% by weight of a lithium salt dispersed in the second polymer

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS12592453B2Multi-layer solid electrolyte separator for a lithium secondary battery and manufacturing method

Publication Date: 2026.03.31 HONEYCOMB BATTERY CO

AI summary

A flame-resistant composite separator for use in a lithium battery, wherein the composite separator comprises at least a first layer and a second layer laminated together, wherein: (A) the first layer comprises a layer of inorganic solid electrolyte (e.g., a sintered solid structure) or a layer of polymer composite comprising 60%-99% by volume of inorganic material particles, inorganic material fibers, and/or polymer fibers dispersed in or bonded by a first polymer; and (B) the second layer comprises a second polymer and from 0.1% to 50% by weight of a lithium salt dispersed in the second polymer; wherein the first layer and the second layer each has a thickness from 20 nm to 100 μm and a lithium-ion conductivity from 10−8 S/cm to 5×10−2 S/cm at room temperature.