Ok a few things:

Batteries don’t need “a few sparks” to catch fire. They will generate plenty of heat if punctured and self-ignite.

You don’t pour water on a grease fire because grease floats and it will spill out of your pot and catch the rest of your kitchen on fire. Also the water will boil and splatter oil everywhere.

Also pouring water on a battery fire is the preferred way to put it out. Many of the chemicals in the battery will release oxygen when heated, so the best way to put it out is to cool it down as much as possible by dousing it with a shitload of water. It isn’t always possible to apply enough water to the core of the fire which is why they are hard to put out. Sand won’t do anything because the fire is self-oxidizing.

Yes lithium metal reacts with water, but that’s not what makes batteries hard to put out.