Thickening of Sulfuric Acid for
Accumulators with AEROSIL® Fumed Silica
The use of AEROSIL® 200 and its compacted version, AEROSIL® 200 V, can improve the limitations of the widely used lead acid accumulators containing liquid electrolytes.
Conventional batteries, like the ones used in most automobiles, usually are not secure regarding acid containment and can only be used in upright positioning. Though this is currently acceptable for paved road conditions, it is not safe in other conditions. Highly corrosive battery acid can flow or leak out in off road conditions, at sea or in the air.
Adding AEROSIL® 200 / 200 V to the battery acid changes the acid to a gel like consistency, and prevents the leaking of the battery content. The accumulator continues to function, but the danger of leaking acid is reduced. Actually, the electrolyte thickened with AEROSIL® 200 / 200 V significantly increases the current capability and service life of the lead accumulators. These improved batteries are now being used in electric vehicles, forklifts, solar plants, radio stations, and emergency generators. AEROSIL® fumed silica is also available as easy to handle water based dispersions, marketed as AERODISP®.
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=> Productinformation and Safety Data Sheets (MSDS) can be displayed or downloaded as a pdf-file at the Productfinder |
| Application: BATTERY GEL |
| AEROSIL® grade |
Concentration in wt% |
Effect |
Incorporation method |
| AEROSIL® 200 |
5 - 6 |
Thickening,
Thixotropy,
Gel Formation |
Cowless-Dissolver, Ultra-Turrax,
Inline Rotor Stator, Silverson Mixer |
| AEROSIL® 200 V |
| AEROSIL® 200 VS (USA) |
| AERODISP® W 7520 N |
25 - 30 |
How to prepare Battery Gels?
There are two methods to incorporate AEROSIL® fumed silica into battery gels.
Dispers AEROSIL® 200 / 200 V directly into the battery acid with 5-6 % concentration.
AEROSIL® 200 is the more effective rheology control additive, especially when low shear mixing equipment is available. The advantages of AEROSIL® 200 V are easier handling, less dust, reduced storage cost and easier processing due to decelerated gelling of the sulphuric acid. The use of AEROSIL® 200 V requires high shear mixing equipment.
Disperse AEROSIL® 200 / 200 V into deionized water with about 12 % loading. Dilute with concentrated sulphuric acid to achieve 37 % acid and about 6 % AEROSIL® fumed silica concentration in the final formulation.
This method does require acid resistant equipment only in the very last step.
- Equipment:
- acid resistant container; Teflon coated
- cooling during dispersion is needed
- Dispersing equipment:
- Cowless-Dissolver 10-30 m/sec tip speed
- Ultra-Turrax
- Ystral Conti-TDS 4
- Silverson Mixer
- Filling Time:
The AEROSIL® fumed silica containing sulfuric acid must be filled into the battery before gelling. Depending on the mixing and shear energy, gelling of the sulfuric acid starts 30 - 50 minutes after mixing with AEROSIL® 200 / 200 V.
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