LDH Air Electrode Assembly for Hydroxide Ion Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Metal-air secondary batteries with layered double hydroxide (LDH) separators face challenges in achieving high charge/discharge performance due to low hydroxide ion conductivity caused by blocking electrolyte permeation into the air electrode layer, leading to decreased performance compared to batteries with general porous polymer separators.
Innovation Solution
An air electrode/separator assembly is designed with a two-layered structure, featuring an internal catalyst layer filled with hydroxide ion conductive materials, electron conductive materials, and an organic polymer, and an outermost catalyst layer with a porosity of 60% or more composed of a porous current collector and LDH, allowing for enhanced hydroxide ion conductivity and catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an LDH separator is used to block zinc dendrite penetration and prevent carbon dioxide inclusion, then reliability is improved, but hydroxide ion conductivity deteriorates due to blocking electrolyte permeation into the air electrode layer
Solution Approach 1:
The air electrode layer is divided into two distinct layers: a first layer adjacent to the LDH separator containing hydroxide ion conductive material, electron conductive material, and catalyst; and a second layer adjacent to the electrolyte containing only catalyst and electron conductive material. This segmentation allows the first layer to facilitate hydroxide ion transfer from the LDH separator while the second layer maintains catalytic activity, resolving the contradiction between blocking dendrites and enabling ion conduction.
Solution Approach 2:
Different regions of the air electrode layer are assigned different compositions and functions. The first layer near the LDH separator is designed with hydroxide ion conductive material to enable ion transfer, while the second layer near the electrolyte is designed with catalyst for electrochemical reactions. This local differentiation allows each region to optimize its specific function, maintaining both reliability and conductivity.
2Object-generated harmful factors
If a porous polymer separator is used to allow electrolyte permeation into the air electrode, then hydroxide ion conductivity is improved, but zinc dendrite penetration and short circuit risk increase
Solution Approach 1:
The first layer of the air electrode layer acts as an intermediary between the LDH separator and the electrolyte. It contains hydroxide ion conductive material that facilitates ion transfer from the dense LDH separator, while the catalyst and electron conductive material enable electrochemical reactions. This intermediary layer resolves the contradiction by enabling ion conduction without requiring the separator itself to be porous.
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 configuration improves charge/discharge performance by creating a wider reaction region and reducing reaction resistance, effectively transferring hydroxide ions and maintaining the benefits of using an LDH separator, such as preventing short circuits and carbon dioxide inclusion.
Implementation Method 1
a battery comprising a layered double hydroxide (LDH) separator that blocks the penetration of zinc dendrite while selectively permeating hydroxide ions
Implementation Method 2
effectively transferring hydroxide ions
Implementation Method 3
Upon discharge, O2 is reduced on an air electrode (positive electrode) side to generate OH−
Implementation Method 4
zinc is oxidized on a negative electrode to generate ZnO
Data Source
AI summary
Provided is an air electrode/separator assembly including a hydroxide ion conductive dense separator and an air electrode layer provided on one side of the hydroxide ion conductive dense separator. The air electrode layer includes: an internal catalyst layer provided closer to the hydroxide ion conductive dense separator and filled with a mixture containing a hydroxide ion conductive material, an electron conductive material, an organic polymer, and an air electrode catalyst (provided that the hydroxide ion conductive material may be the same material as the air electrode catalyst, and provided that the electron conductive material may be the same material as the air electrode catalyst); and an outermost catalyst layer provided away from the hydroxide ion conductive dense separator having a porosity of 60% or more, composed of a porous current collector and a layered double hydroxide (LDH) covering a surface thereof.