Did anyone really read the title thinking that the article was about alkaline batteries? I think not.

The title is not misleading. It's incomplete, as titles are by nature. Titles are not supposed to include all caveats and modifications. The title also doesn't say that the decline is measured in dollars. Probably the price has dropped much less or much more when measured in other currencies that have moved relative to the dollar. The title also doesn't mention whether it's adjusted for inflation. It also doesn't specify whether that's the price at the consumer level or the price paid by manufacturers. Whether it's when you buy the battery in America or somewhere else on the planet.

As long as a title doesn't deliberately seek to mislead, it's not misleading. The intended audience expected this to be about lithium ion batteries.