The invention provides an anode comprising a nanocomposite of graphene-oxide and a silicon-based polymer matrix. The anode exhibits a high energy density such as ˜800 mAhg−1 reversible capacity, a superlative power density that exceeds 250 kW/kg, a good stability, and a robust resistance to failure, among others. The anodes can be widely used in a lithium-ion battery, an electric car, a hybrid electromotive car, a mobile phone, and a personal computer etc. The invention also provides a liquid phase process and a solid-state process for making the nanocomposite, both involving in-situ reduction of the graphene-oxide during a pyrolysis procedure.