Lithium-Air Battery Conductive Coating Segmentation
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Solution Overview
Problem
Lithium-air batteries face challenges in increasing discharge capacity and cycle life due to limitations in the amount of conductive material that can be coated, which also restricts the resolution of over-voltage issues.
Innovation Solution
A lithium-air battery design that includes a gas diffusion layer with a coating of a first conductive material on the air electrode and a coating of a second conductive material on the separator, allowing for a sufficient amount of conductive material to be used, with the layers facing and in direct contact with each other to enhance discharge capacity and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of conductive material is increased to improve discharge capacity, then the discharge capacity increases, but the conductive material layers split and the manufacturing becomes difficult
Solution Approach 1:
The conductive material coating is divided into two separate locations: the air electrode and the separator. Each location receives a portion of the total conductive material, preventing the excessive thickness that causes layer splitting while still achieving the desired total amount of conductive material for high discharge capacity.
Solution Approach 2:
The separator acts as an intermediary component that also serves as a substrate for conductive material coating. By coating the separator with conductive material, the system effectively increases the total conductive material content without over-coating either the air electrode or separator alone, thus avoiding layer splitting.
2Quantity of substance
If the coating amount of conductive material is restricted to prevent layer splitting, then the manufacturing stability is maintained, but the discharge capacity cannot be increased enough
Solution Approach 1:
The total conductive material requirement for high discharge capacity is segmented across two components (air electrode and separator). This allows each component to have a moderate coating amount that maintains manufacturing stability, while the combined effect achieves the desired high discharge capacity.
Solution Approach 2:
Instead of increasing conductive material amount in a single dimension (one component), the solution distributes the conductive material across two dimensions (air electrode and separator). This multi-dimensional approach achieves higher total conductive material content without the drawbacks of excessive coating at any single location.
3Reliability
If the coating amount of conductive material is restricted, then layer splitting is prevented, but the over-voltage problem and cycle life cannot be significantly improved
Solution Approach 1:
The conductive material is segmented between the air electrode and separator, allowing sufficient total conductive material to be used for improving cycle life and reducing over-voltage, while each individual coating remains at a manageable thickness that prevents manufacturing issues.
Solution Approach 2:
The separator, coated with conductive material, serves as an intermediary that facilitates better electrochemical performance. This additional conductive material on the separator contributes to reduced over-voltage and improved cycle life without requiring excessive coating at any single location.
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 battery achieves significant improvements in discharge capacity and cycle life by utilizing a sufficient amount of conductive material on both the air electrode and separator, demonstrating a substantial increase in areal discharge capacity and extended cycle life.
Implementation Method 1
the separator includes a coating layer of a second conductive material for coating the surface of the separator... the second conductive material in the separator and the first conductive material in the air electrode may be different from each other
Implementation Method 2
The gas diffusion layer of the air electrode may include any one selected from the group consisting of carbon cloth, carbon paper, carbon felt, selective oxygen-permeable membrane
Data Source
Figure 1~2
AI summary
The present invention provides a lithium-air battery comprising: an air electrode using oxygen as a positive electrode active material; a negative electrode which is disposed apart from the positive electrode; and a separator which is immersed in an electrolyte disposed between the positive electrode and the negative electrode, wherein the air electrode comprises a gas diffusion layer coated with a conductive material, and the separator has a part coated with the conductive material.