Materials for rechargeable lithium-ion batteries

The lithium-ion battery is the most promising battery candidate to power battery-electric vehicles. For these vehicles to be competitive with those powered by conventional internal combustion engines, significant improvements in battery performance are needed, especially in the energy density and power delivery capabilities. Recent discoveries and advances in the development of electrode materials to improve battery performance are summarized. Promising substitutes for graphite as the anode material include silicon, tin, germanium, their alloys, and various metal oxides that have much higher theoretical storage capacities and operate at slightly higher and safer potentials. Designs that attempt to accommodate strain owing to volumetric changes upon lithiation and delithiation are presented. All known cathode materials have storage capacities inferior to those of anode materials. In addition to variations on known transition metal oxides and phosphates, other potential materials, such as metal fluorides, are discussed as well as the effects of particle size and electrode architecture. New electrolyte systems and additives as well as their effects on battery performance, especially with regard to safety, are described.