LDH Separator Plugging Pores to Block Zinc Dendrites

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Solution Overview

Problem

Secondary zinc batteries face short circuits due to metallic zinc dendrites penetrating through separators, leading to reduced service life, despite the use of layered double hydroxide (LDH) separators that selectively permeate hydroxide ions and block zinc dendrites.

Innovation Solution

A LDH separator with a porous polymeric substrate having pores plugged with LDH, achieving a mean porosity of 0.03% to less than 1.0%, which effectively prevents zinc dendrite penetration by densifying the substrate and maintaining hydroxide ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a porous separator is used to allow ion permeation, then ion conductivity is improved, but zinc dendrites can penetrate through the separator causing short circuits

Engineering Contradiction:

Improveion conductivityVSAvoidshort circuit prevention

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses a composite structure combining a porous substrate with an LDH coating layer. The porous substrate provides ion conductivity while the LDH coating layer blocks zinc dendrite penetration. This composite approach allows the separator to simultaneously achieve good ion permeation properties and effective dendrite blocking capability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs a porous substrate as the base structure of the separator. This porous structure enables efficient ion transport between electrodes while providing a framework for the LDH coating. The porosity is optimized to balance ion conductivity with dendrite blocking when combined with the LDH layer.

Inventive Principle:

Principle #31Porous materials

2Reliability

If the separator is made dense to block zinc dendrites, then short circuit prevention is improved, but ion permeation is reduced

Engineering Contradiction:

Improveshort circuit preventionVSAvoidion conductivity

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies different properties to different parts of the separator structure. The porous substrate maintains high porosity for ion conductivity, while the surface layer is covered with LDH coating that provides dense blocking against zinc dendrites. This local differentiation allows each layer to optimize its function without compromising the other.

Inventive Principle:

Principle #3Local quality

3Reliability

If a thick separator is used to prevent dendrite penetration, then short circuit prevention is improved, but flexibility and strength are reduced

Engineering Contradiction:

Improveshort circuit preventionVSAvoidflexibility and strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent extracts the dendrite-blocking function from the bulk separator structure and concentrates it in a thin LDH coating layer on the surface. This allows the majority of the separator thickness to remain as porous substrate, maintaining flexibility and strength while achieving effective dendrite blocking with minimal additional thickness.

Inventive Principle:

Principle #2Taking out (Extraction)

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 LDH separator significantly enhances the prevention of short circuits caused by zinc dendrites while maintaining flexibility and strength, ensuring effective ion conductivity and gas/water impermeability, thus extending the service life of secondary zinc batteries.

Implementation Method 1

layered double hydroxide (LDH) separators that selectively permeate hydroxide ions while blocking the penetration of zinc dendrites

Methodology Applied

Scientific EffectSelective permeation: Semipermeable Membrane

Implementation Method 2

a LDH with which pores of the porous substrate are plugged

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentUS11145935B2LDH separator and zinc secondary cell

Publication Date: 2021.10.12 NGK INSULATORS LTD

AI summary

Provided is a layered double hydroxide (LDH) separator including a porous substrate made of a polymeric material; and a LDH with which pores of the porous substrate are plugged. The LDH separator has a mean porosity of 0.03% to less than 1.0%.