Not a valid question.
The PowerCore II 10000 is a portable charger, it is a battery, it requires a charger which it connects to which then connects to the local mains wall socket.
That charger then must plug into the German power socket, so the question is actually one of your chosen charger.
In theory if you plugged in the cheapest nastiest charger designed only for say 110V and you then plugged that charger into 220V then it would fry and be rendered totally permanently bust, or worse, pass on a dangerously high power to the Powercore.
In general however, most chargers are international voltage, they will easily handle any voltage worldwide, you need only a physical plug shape adapter, they will then output the required voltage and current to the Powercore II 10000.
So really you need to ask about your charger....