Ionic liquids are well suited to the electrochemical synthesis of freestanding metallic nanowires as well as macroporous metals and semiconductors. Such materials are potentially interesting for future generation Li-ion batteries. As the energy density of current Li-ion batteries barely exceeds 0.15 kWh/kg (in contrast to the 12 kWh/kg of hydrocarbons), there is a need for new anode and cathode materials if electrically driven cars are to have more than a 150 km cruising range at an affordable price. Freestanding aluminum nanowires and macroporous aluminum are easily feasible from AlCl3-based ionic liquids and show promising charge/discharge behavior even with ionic liquids as electrolytes. The challenges and the potential to make nanowires or macroporous structures of semiconductors (Si, Ge) are also briefly discussed.
