No moving parts, no maintenance
Let's see you couple that battery directly to a wheel and see how far that gets you moving before you wish you had moving parts between them. I am looking forward to electric cars being more common but blind optimism doesn't help, the fact is you still need an electric motor and batteries have too small a charge, too short a life and too much environmental impact.
You still have maintenance on the electric motor, you still have a motor and you still have toxic emissions albeit they are now suspended until the battery replacement.
Thus spake the master programmer: "After three days without programming, life becomes meaningless." -- Geoffrey James, "The Tao of Programming"