Exactly. Table salt has an LD50 of 0.5-1g/kg, 1.5-3x more toxic. I weigh ~85kg, I'd have to eat about 46 cubic centimeters of potassium ferrocyanide (on the conservative side) to consume an LD50 worth.

If you're talking about the chemicals in batteries we have today, the LD50 is probably way lower for most of them. If we're talking about batteries for consumer electronics, you'd have to eat (density wise) multiple batteries worth of potassium ferrocyanide to hit LD50.