Here are some things I have learned that may be useful to others:
1. The Energi uses what is called the Euro key fob. It looks identical to fobs used on other Ford products but is electrically different than the Edge, F150, etc. It even has the same FCC ID as those other fobs which leads to a lot of confusion on eBay. I think only the Escape and Focus EV use the same fob as the Energi. If you are buying a used fob, be sure it has 7812A-xxxx on the right side under the mechanical key head.
2. The Energi fob has two electronic key plus the mechanical key. If you look on the right side of the steering column, you will see a notch with a radiation symbol under it. When the proximity key isn't working (maybe has a dead battery), you can hold the fob in the slot and the car will sense the transponder key in the fob. You can still drive the car with a dead battery in the fob.
3. You can make a more traditional door key from one of the Focus ignition keys available on eBay. You have to cut 7mm off of the ignition key to make it the correct length for a door key. It is difficult to find someone to cut an eBay sidewinder key. The cutters are expensive and they want to sell you the key blank to help pay off their investment. I have been able to cut my own keys but you have to have a lathe. Here is a link to how I cut sidewinder keys: