We report amorphous-Si nanowire shell anodes, supported by NiSix nanowire cores, by catalyst-free two-step SiH4 chemical vapor deposition, where the metallic core acts as a mechanical supporter and a kinetically unlimited charge supplier. We have achieved highly reversible capacitance of over 3000 mAh g(-1) even at a 2C rate, with stable cyclic retention which stems from the altered electrochemical reactions with relatively small volume expansion routes by a kinetic effect.