Two-Phase Electrolytic Cell for High-Rate Hydrogen Generation
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Solution Overview
Problem
Current systems for hydrogen production through electrolysis are inefficient for large-scale applications, as they have a low hydrogen evolution rate, leading to high capital investment requirements and limited scalability in meeting renewable energy demands.
Innovation Solution
The use of a two-phase electrolytic system with a zinc-based solution and specially adapted electrodes, where the charging phase involves zinc deposition and oxygen evolution, followed by a discharging phase with a short circuit to enhance hydrogen evolution, along with optimized electrode gap and zinc concentration, and optional heating to reduce internal resistivity and increase production rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electrolysis systems are used for hydrogen production, then hydrogen can be generated, but the hydrogen evolution rate is low leading to high capital investment requirements
Solution Approach 1:
The electrolysis process is divided into two distinct phases: a charging phase where zinc is deposited and oxygen is evolved, and a discharging phase where zinc dissolves and hydrogen is evolved. This segmentation allows optimization of each phase independently, achieving high hydrogen evolution rates during discharge while using simple electrode configurations that reduce capital investment.
Solution Approach 2:
The system operates periodically by alternating between charging and discharging phases. During the charging phase, zinc deposition prepares the electrode for high-rate hydrogen evolution in the subsequent discharging phase. This periodic operation enables the system to achieve high productivity during hydrogen production while maintaining simpler device requirements overall.
2Productivity
If conventional electrolysis systems are used, then hydrogen production can occur, but scalability for large-scale applications is limited
Solution Approach 1:
The system dynamically switches between charging and discharging modes based on operational requirements. The electrodes transition between different chemical states (zinc deposition during charging, zinc dissolution during discharging), enabling the system to adapt to varying production demands and scale from small to large applications by adjusting operational parameters rather than fundamentally changing the system architecture.
3Device complexity
If electrode area is reduced to lower capital investment, then device cost decreases, but hydrogen production rate may be insufficient
Solution Approach 1:
The system changes operational parameters by switching between charging and discharging phases. During the discharging phase, the electrochemical conditions are optimized for high-rate hydrogen evolution from zinc dissolution, allowing smaller electrode areas to achieve the same hydrogen production rates that would require much larger electrodes in conventional continuous electrolysis systems.
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 approach significantly increases hydrogen evolution rates, reducing the required electrode surface area and capital investment, making it suitable for large-scale renewable energy storage and meeting demand fluctuations.
Implementation Method 1
During the charging phase of the cell containing a solution of a zinc salt, the first and second electrodes are connected to an external electric energy source. The electron flow supported by the external electrical source is fed to the first electrode where zinc of the zinc salt is reduced. The electrons, fed to the first electrode, are withdrawn from the second electrode where oxygen is evolved via the electrooxidation of water
Implementation Method 2
When hydrogen is required, that is during the discharging phase of operation, the known prior art teaches to connect the first and second electrodes to an external resistive electrical circuit which allows the electrons to flow from the first electrode, where zinc is then dissolved via oxidation, towards the second electrode, on the surface of which they generate hydrogen via electroreduction of water
Data Source
AI summary
Two phased production of hydrogen involving an electrolytic cell containing first and second electrodes and a solution comprising a metal salt. The first and second electrodes are connected to an external electric energy source during a charging phase, which deposits the metal of the metal salt on the first electrode and evolves oxygen on the second electrode. Once the charging phase has been completed the first and second electrodes are disconnected from the external electric energy source with the cell containing the deposited metal kept in a standby condition until hydrogen production is required. During a discharging phase, the first and second electrodes are short circuited, whereby the metal is dissolved from the first electrode and hydrogen is evolved from the second electrode without any appreciable simultaneous withdrawal of electrical energy. The production of hydrogen is thereby increased accordingly. Variations of the above are also provided.