Lithium Ion vs Lead Acid

One of my nieces' husbands. . . hmm, lets rephrase that. :o The husband of one of my nieces is an engineer with an electric vehicle/lithium battery company and this year he had been twice to Europe to replace the batteries and/or drives in a couple of large ferries. Guess it's coming.

I tried to get him to design me an electric toad that could be towed 4 down and recharge if necessary while doing do. He declined!