[de_watcher]

Not counting turbopumps for chemical engines there is also an electric propulsion when in space.

[ben-schaaf]

To expand on this there's these things called ion thrusters that use an electrically generated magnetic field to accelerate gas particles at extremely high velocities out the spacecraft thereby generating thrust. These are stupidly efficient but also very low thrust. Due to the high power usage I don't see much of an application for even incredibly dense batteries as you still need a sufficiently large power source anyway - though I'm no rocket scientist.