Help with charging lithium ion batteries
Any time that you connect batteries in parallel, you generate a system where one charges the other or one discharges the other.  Unless the cells are very tightly matched, this does not work well.  

Connecting them in series for a higher voltage pack is possible, but unless the cells are matched very well and of a chemistry that allows this without extra circuitry, you will need to balance. 

The saying "a chain is only as strong as its weakest link" applies to a mixed combination of lithium cells.  You can only source as much power until your smallest cell is drained.  Then you start to destroy it.  

Lithium batteries are highly dangerous.  The can catch fire and burn very rapidly when charged improperly.  Just by asking this question it is highly suggestive that you may not have the knowledge to put something like this together safely.  I would never attempt it, because there is no benefit over using matched cells.