an electrical current drives the lithium ions out of the...

an electrical current drives the lithium ions out of the cathode, into a fluid filled with electrically conducting ions, and into another layer, called the anode, which is made up of stacks of graphite

http://www.livescience.com/50726-how-tesla-home-batteries-work.html

I am a holder but not a fan of MOZ as I have held them for a loooooooong time and been disapointed many times, however I am a fan of the graphite story unfolding, and if the new gen EV's and the powerwall are making ME think I want one each, then I am sure many more people around the world feel the same ... unfortunatley I hold O&G stocks as well but IMO graphite , lithium , cobalt are going to be claer winners over the next decade.
It took a few hundred million people to kick of the industrial revolution............there  billions of people on the planet now ...just imagine this battery storage and EV / save the planet revolution takes off , I get what Elon M is on about GL