Lithium-ion batteries burn. But the topic was "modern batteries", which at the instant moment means LiFeP batteries, not "previous-generation batteries".

Lithium is anyway not favored for use in utility-scale storage, where its light weight offers no compelling value. Up-and-coming chemistries include iron-air (no explosions), calcium-antimony (no explosions), and bromine-zinc (no explosions). Hundreds of other chemistries are available.