Composite Gas Diffusion Layer for Anode Moisture Retention
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Solution Overview
Problem
Existing gas diffusion layers in electrochemical hydrogen compressors lead to anode drying and poor compression performance, especially in low-humidity environments, due to unbalanced water management and high ohmic impedance.
Innovation Solution
A composite gas diffusion layer with a layered structure comprising a base layer, hydrophobic layer, and water-absorbing layer, where the water-absorbing layer includes carbon black, a water-absorbing agent, and solvents, and the hydrophobic layer includes carbon black, a hydrophobic agent, and a binder, is designed to enhance water absorption and retention, preventing anode drying and reducing ohmic impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gas diffusion layer structure (hydrophobic base layer + super hydrophobic microporous layer) is used, then the gas diffusion layer provides basic gas transport function, but the anode dries up during long-term operation leading to poor compression performance and high ohmic impedance
Solution Approach 1:
The gas diffusion layer is segmented into three distinct functional layers: a hydrophobic base layer for gas transport, a hydrophobic microporous layer for water management, and a hydrophilic layer adjacent to the anode for water absorption and retention. This segmentation allows each layer to perform its specific function optimally, preventing anode drying while maintaining compression performance.
Solution Approach 2:
Different regions of the gas diffusion layer are assigned different hydrophobicity properties: the base layer and microporous layer are hydrophobic to facilitate gas transport and water removal, while the layer adjacent to the anode is hydrophilic to absorb and retain water locally, preventing anode drying without affecting overall gas diffusion.
2Productivity
If the gas diffusion layer does not retain water effectively, then gas transport is facilitated, but ohmic impedance increases and compression efficiency decreases
Solution Approach 1:
The hydrophilic layer acts as an intermediary between the hydrophobic microporous layer and the anode, absorbing excess water from the microporous layer and retaining it near the anode. This intermediary function maintains optimal humidity at the anode interface, reducing ohmic impedance while allowing the hydrophobic layers to continue facilitating gas transport.
3Ease of manufacture
If a single-layer hydrophobic gas diffusion layer is used, then manufacturing is simple, but water management is unbalanced leading to anode drying
Solution Approach 1:
The gas diffusion layer is divided into three sequentially stacked layers with distinct functions: hydrophobic base layer, hydrophobic microporous layer, and hydrophilic layer. This segmentation enables optimized water management while maintaining a relatively simple sequential fabrication process, balancing manufacturing ease with functional complexity.
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 gas diffusion layer effectively maintains moisture, improving compression performance and reducing ohmic impedance, particularly in low-humidity conditions, by synergistically combining water absorption and hydrophobic properties, thus enhancing the electrochemical hydrogen compressor's efficiency and operational life.
Implementation Method 1
a water-absorbing layer, and the base layer, the hydrophobic layer, and the water-absorbing layer are sequentially stacked
Implementation Method 2
promote the water absorption and water retention effect of the gas diffusion layer
Implementation Method 3
a hydrophobic layer, and the base layer, the hydrophobic layer, and the water-absorbing layer are sequentially stacked
Implementation Method 4
the electroosmotic migration effect in the proton exchange membrane allows a large amount of water to migrate from the anode to the cathode
Implementation Method 5
the anode undergoes a hydrogen oxidation reaction to generate protons
Implementation Method 6
the protons transmitted from the anode through the electrolyte membrane combine with the electrons transmitted from the external circuit to recombine into hydrogen molecules, converting electrical energy into compression energy
Data Source
AI summary
The present application relates to the technical field of compressors, and in particular, to a composite gas diffusion layer, a preparation method thereof, a membrane electrode, and an electrochemical hydrogen compressor. The composite gas diffusion layer applied to an electrochemical hydrogen compressor includes: a base layer, a hydrophobic layer, and a water-absorbing layer, and the base layer, the hydrophobic layer, and the water-absorbing layer are sequentially stacked. The composite gas diffusion layer of the present application is designed for an inherent problem of the drying up of the anode during the operation of the electrochemical hydrogen compressor, and by arranging a layered structure for water absorption/hydrophobicity, the composite gas diffusion layer can improve the compression performance of the membrane electrode of the compressor and reduce the ohmic impedance of the membrane electrode.