PEM Fuel Cell Electrolysis Activation Under Humid Gas Supply
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Solution Overview
Problem
Current methods for activating proton exchange membrane fuel cells (PEMFCs) are inefficient in improving electrochemical performance, especially at high current densities, and do not effectively reduce platinum oxides formed during electrolysis.
Innovation Solution
A method involving an activation phase with an external electric supply applying a voltage greater than or equal to 1V and a humid gas with 40% ≤ RH < 100% is used, causing carbon corrosion and altering porosity to enhance access to catalytic sites, while maintaining the reversibility of platinum oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional low-voltage generator operation (≤1V) is used for activation, then the membrane can be hydrated, but the electrochemical performance at high current density cannot be improved
Solution Approach 1:
The patent inverts the conventional activation approach by using electrolysis mode instead of generator mode. By applying a voltage ≥1V in electrolysis mode, the method achieves both membrane hydration and improved electrochemical performance at high current density, resolving the contradiction that prevented both objectives from being met simultaneously
Solution Approach 2:
The patent changes the activation parameter from low voltage (≤1V) to high voltage (≥1V) and switches the operational mode from generator to electrolysis. This parameter change enables simultaneous achievement of membrane hydration and enhanced electrochemical performance, overcoming the limitations of conventional low-voltage activation
2Reliability
If electrolysis operation is used to form platinum oxides, then the catalytic layers are modified, but the platinum oxides cannot be reduced
Solution Approach 1:
The patent employs periodic alternation between electrolysis mode (to form platinum oxides and modify catalytic layers) and generator mode (to reduce platinum oxides). This periodic switching enables both catalytic layer modification and oxide reduction to occur sequentially, resolving the contradiction where only formation was possible before
Solution Approach 2:
The patent temporarily forms platinum oxides during electrolysis phase, then reduces and recovers them during generator phase. This cycle of discarding (forming) and recovering (reducing) platinum oxides enables both catalytic modification and oxide removal, overcoming the one-way formation limitation
3Reliability
If extensive conditioning phase is used to activate catalytic layers, then nominal performance is reached, but activation time is prolonged
Solution Approach 1:
The patent performs preliminary high-voltage electrolysis activation before nominal operation to pre-modify catalytic layers and hydrate the membrane. This preliminary action accelerates the activation process, enabling nominal performance to be reached faster without extensive conditioning time
Solution Approach 2:
The patent uses high-voltage electrolysis mode during activation to accelerate catalytic layer modification and membrane hydration. This parameter change from conventional low-voltage generator mode dramatically reduces the time required to achieve nominal performance while maintaining activation effectiveness
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 method significantly improves the cell's performance by increasing current density and reducing the number of cells needed in a stack, thereby lowering costs, with minimal additional conditioning time and no irreversible degradation of the catalyst.
Implementation Method 1
A method involving an activation phase with an external electric supply applying a voltage greater than or equal to 1V... causing carbon corrosion and altering porosity
Implementation Method 2
A method involving an activation phase with an external electric supply applying a voltage greater than or equal to 1V and a humid gas with 40% ≤ RH < 100%
Implementation Method 3
The fuel cell thus operates in electrolysis during the activation phase. It receives an electric current and water vapour coming from the humid gas, and produces, in particular, hydrogen and oxygen
Data Source
AI summary
A method may activate a fuel cell including a plurality of electrochemical cells in a stack, the fuel cell being intended to operate, during at least one nominal operating phase, as an electric generator. Such a method may include, during an activation phase by electrolysis, prior to the at least one nominal operating phase: electrically supplying the fuel cell by an external electric generator, the electric supply being configured to apply an activation voltage greater than the voltage of the cell in an open circuit (OCV); fluid supplying a humid gas fluid at a first electrode and/or a second electrodes. The humid gas may have a relative humidity (RH) such that 40%≤RH<100%. The fuel cell may operate in electrolysis during the activation phase called by electrolysis.