How to reduce current?
My component is a battery, which should not be able to draw more than
  150mA from the power source.


You aren't looking for a current divider but rather a current limiter and this is an active device because, in principle, it doesn't restrict current into (or out of) a device until the "limit value" is reached.

So, trying to make one from passive components or diodes isn't going to be effective as a protection against over charging with too high a current.