Question

Does the loading-curve from a capacitor look like the loading-curve from a device with a lithium ion accumulator?

Answer 1

No. The capacitor voltage will rise linearly if charged with constant current, but the li-ion accumulator voltage will rise nonlinearly:
http://www.powerstream.com/ultra-light.htm

Same applies to discharge curves, see http://www.mpoweruk.com/performance.htm
for example.

Answer 2

In school we drew a t-q Diagramm and it was a curve - some e function not a linear function.

Answer 3

Yes, if you have a constant voltage source, a resistor and a capacitor, it's an exponential curve:
http://en.wikipedia.org/wiki/RC_circuit#Time-domain_considerations

If you have a constant current (not voltage) source the voltage of the capacitor will rise linearly.