Its an interesting idea, but with all the hazards of lithium ion batteries (Which are some of the best rechargable batteries out there), I have to wonder how it behaves during a crash. If you hit your head and it busts the battery are you now covered in highly flammable liquid? Is it going to catch fire when the lithium hits the air?
Current helmets are made to deform when you impact something so that it absorbs the impact (It is hard up to a point and plastic after that). With wires and electronics and batteries in the helmet, how good is it really at protecting your head. I wouldn't invest in or buy this product until I saw more safety testing data.