In view of accelerating climate change, the transition to an environmentally sustainable energy economy is among the most pressing global challenges. Recent years have seen tremendous progress in the generation of clean electric energy from renewable sources such as photovoltaic and wind turbines. However, the potential of renewable energy resources remains largely untapped because energy storage technology is lacking behind: Grid-level energy storage is needed to compensate for fluctuations in solar and wind energy production with the weather and the time of day; improved high-energy-density storage is needed for electric vehicles (and aircrafts) to become truly competitive with conventional combustion engines in range and refuel time.
