Which battery type uses a glass mat to absorb and hold the electrolyte?

• A. Wet-cell battery
• B. Nickel-cadmium battery
• C. Lithium-ion battery
• D. Absorbed Glass Mat (AGM) battery

Answer: (D)

The key idea here is how the electrolyte is contained inside the battery. An Absorbed Glass Mat (AGM) battery keeps the electrolyte soaked into a fiberglass mat that sits between the plates, immobilizing the liquid and making the battery maintenance-free and spill-resistant. This mat acts like a sponge, holding the electrolyte in place even when the battery is oriented or jostled.

In contrast, a wet-cell battery uses a free-flowing liquid electrolyte inside the case, which isn’t held in a mat and can spill or vent under harsh conditions. Nickel-cadmium cells use a different alkaline electrolyte arrangement that isn’t absorbed into a glass mat, and lithium-ion cells rely on liquid or gel-based electrolytes with separators rather than a glass mat to hold the electrolyte. So, the defining feature that matches the description—holding electrolyte in a glass mat—is the AGM design.