Air Electrode-Separator Assembly for Hydroxide Ion Conduction
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Solution Overview
Problem
Metal-air secondary batteries face issues with low hydroxide ion conductivity due to the use of LDH separators that block electrolyte permeation, leading to decreased charge/discharge performance and increased overvoltage, and the challenge of arranging LDH platy particles continuously in the planar direction is difficult.
Innovation Solution
An air electrode/separator assembly is constructed using a hydroxide ion conductive composite material with hydrophilic fibers supporting interconnected hydroxide ion conductive particles, particularly LDH platy particles, to enhance hydroxide ion conductivity and reduce overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an LDH separator is used to block electrolyte permeation and prevent dendrite penetration, then reliability is improved, but hydroxide ion conductivity deteriorates
Solution Approach 1:
The patent employs a porous polyolefin nonwoven fabric as the base separator structure, which provides both mechanical integrity and controlled porosity. The porous structure allows selective permeation - blocking zinc dendrites while maintaining pathways for hydroxide ion transport through the pores, thus resolving the contradiction between reliability and ion conductivity.
Solution Approach 2:
The patent creates a composite structure by combining the porous polyolefin nonwoven fabric with a hydrophilic polymer coating layer. This composite material integrates the dendrite-blocking capability of the porous substrate with the hydroxide ion conductivity of the hydrophilic polymer, simultaneously achieving both reliability improvement and harmful factor reduction.
2Reliability
If an LDH separator is used to prevent short circuit, then reliability is improved, but charge/discharge performance deteriorates
Solution Approach 1:
The porous polyolefin nonwoven fabric provides a three-dimensional network structure with controlled pore size and distribution. This porous architecture ensures reliable short circuit prevention while maintaining sufficient ion transport pathways, thereby preserving charge/discharge performance despite the use of a separator.
Solution Approach 2:
The patent applies local quality enhancement by coating only the surface of the porous separator with hydrophilic polymer. This localized modification provides the necessary ion conductivity at the critical interface without compromising the overall porous structure's mechanical and transport properties, thus maintaining productivity.
3Object-generated harmful factors
If LDH platy particles are arranged continuously in planar direction, then hydroxide ion conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes self-service by employing a dip-coating process where the hydrophilic polymer solution automatically forms a uniform coating layer on the porous separator. The capillary action and surface tension of the solution naturally promote continuous particle distribution without requiring complex external arrangement mechanisms, thus improving conductivity while minimizing manufacturing complexity.
Solution Approach 2:
The patent introduces a hydrophilic polymer solution as an intermediary medium to facilitate the uniform distribution of LDH platy particles. This intermediary carries the particles and enables their continuous arrangement during the coating process, achieving high ion conductivity through a relatively simple manufacturing step.
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 assembly improves hydroxide ion conductivity, increasing the reaction rate of charge/discharge reactions and reducing overvoltage by ensuring continuous contact of LDH platy particles, thereby enhancing battery performance.
Implementation Method 1
a catalyst layer that covers one side of the hydroxide ion conductive separator and comprises an air electrode catalyst, a hydroxide ion conductive composite material, an electrically conductive material, and a binder
Implementation Method 2
a plurality of hydroxide ion conductive particles supported on a surface of the hydrophilic fibers in an interconnected manner
Implementation Method 3
At the air electrode, during discharge an oxygen reduction reaction (ORR) that produces hydroxide ions occurs
Implementation Method 4
during charging an oxygen evolution reaction (OER) that consumes hydroxide ions and produces oxygen occurs
Implementation Method 5
a battery including a layered double hydroxide (LDH) separator that blocks the penetration of zinc dendrites while selectively allowing hydroxide ions to pass through
Implementation Method 6
carbon dioxide in the air passes through the air electrode, dissolves in the electrolytic solution, and precipitates an alkali carbonate
Data Source
AI summary
There is provided an air electrode/separator assembly including a hydroxide ion conductive separator, a catalyst layer that covers one side of the hydroxide ion conductive separator and includes an air electrode catalyst, a hydroxide ion conductive composite material, an electrically conductive material, and a binder, and a gas diffusion electrode arranged on the catalyst layer opposite to the hydroxide ion conductive separator side. The hydroxide ion conductive composite material contains hydrophilic fibers and a plurality of hydroxide ion conductive particles supported on a surface of the hydrophilic fibers in an interconnected manner.