Metal-free water electrolyzer
Carbon fibers with sodium sulfate electrolyte and a designed separator system address the cost and safety issues of existing electrolytic hydrogen production, enabling efficient and scalable hydrogen/oxygen separation.
Patent Information
- Application Number
- DE202025000379
- Authority / Receiving Office
- DE · DE
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2025-04-24
- Estimated Expiration
- 2035-02-28
AI Technical Summary
Existing electrolytic hydrogen production methods using platinum electrodes and sulfuric acid electrolytes are costly and pose environmental and safety risks, while metal-based electrodes suffer from corrosion, and finding suitable electrolytes for carbon fiber systems is challenging.
Employing carbon fibers with sodium sulfate as an electrolyte, which is non-toxic and recyclable, and designing a separator with carbon electrodes and small holes to prevent gas mixing, allowing for efficient hydrogen and oxygen production using green electricity.
Achieves cost-effective and safe hydrogen production with high electrical penetration and separation efficiency, enabling scalable systems from demonstration to industrial scales.
Smart Images
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Abstract
Description
[0001] There are various devices for the electrolytic production of hydrogen, each with its own design, electrode material, and suitable electrolyte. Each design meets certain requirements (e.g., the ability to refill electrolyte water, extract gases, separate gas types, etc.).
[0002] A famous example is the "Hoffmann water decomposition apparatus." The glass body makes it possible to visualize the internal processes, the separation of oxygen and hydrogen, and the possibility of refilling used water during operation. The electrodes used are platinized platinum electrodes, and sulfuric acid is used as the electrolyte. This makes production expensive, because a large electrode surface requires a large electrode, and manufacturing one from platinum is very expensive. On the other hand, the use of sulfuric acid is actually not very problematic; however, if the glass apparatus bursts, it can pose a danger to the eyes, skin, and the environment. Other solutions use different metal electrodes (e.g., titanium-coated stainless steel), which are usually subject to a certain degree of corrosion and therefore require high maintenance.
[0003] The combination of carbon fibers with suitable electrolytes represents an attractive, inexpensive, and safe alternative. The extremely large surface area of the very thin individual fibers enables high throughputs of electricity and the resulting gas. Finding suitable electrolytes alone appeared difficult. In series of tests, sodium sulfate dissolved in the electrolyte water proved to be suitable. It is nontoxic (available commercially as a laxative), relatively inexpensive, and easily recycled. The electrolyte is not consumed during operation. Sodium sulfate is added only when refilling the battery.
[0004] The drawing shows a possible design. Here, carbon fibers are inserted inside the separator tube (negatively polarized, "hydrogen side") and wired; the tube is also wrapped with carbon fibers on the outside and wired (positively polarized, "oxygen side"). The housing consists of standard tubing (prototype made of "HT tubing" in sizes DN40, 50, and 90), which can also be made of transparent material (used in teaching). The separator must have numerous, preferably small, drilled holes at the level of the carbon fibers. This allows for an exchange of the otherwise static charges while simultaneously preventing mixing of the gases. If small holes are not possible, an additional layer of permeable material (filter fleece) is recommended.
[0005] When a direct current is applied, hydrogen (inside) and oxygen (outside) gases are formed. The gases can be continuously removed from the respective gas taps. Filling with water during operation is also possible. Such a setup allows for the production of an electrolyzer for hydrogen / oxygen production with minimal resources. This is known as "green hydrogen," for example, when using "green electricity." Through cascading or scaling, various system sizes are possible, from demonstration units to large-scale industrial plants. List of reference symbols 1 tap “hydrogen” 2 Oxygen tap 3 Housing (plastic tube) 4 Pure water with dissolved electrolyte (e.g. Na2SO4) 5 Inner reactor tube with separator (carbon electrode inside; “negatively polarized”) 6 Carbon electrode around the separator tube
Claims
[1] Carbon fibers as fabric or roving as electrode material for the electrolysis of water. [2] Sodium sulfate dissolved in water as a suitable electrolyte for the carbon fiber electrodes. [3] 3. Cylindrical separator tube, which has the following design: a negatively polarized carbon electrode inside, a positively polarized carbon electrode outside; holes in the area of the carbon electrodes for charge equalization while simultaneously separating the gases. If separation is insufficient, layers of permeable material such as filter fleece can be placed between the carbon fibers and the tube.