Especially in the last few years, the varieties of Lithium Ion battery types have increased significantly. The original Li-Ion batteries used a graphite anode structure, and a Lithium Cobalt Oxide cathode. This combination provided good energy density and high capacity, but is relatively expensive, and uses Cobalt which is a relatively rare and hard to obtain material. As Li-Ion batteries became more popular, there was a need to find lower cost materials as well as optimize their performance for new and different kinds of applications. Some of the other Cathode materials which are now in use include Lithium-Manganese-Oxide, Lithium Iron Phosphate, Lithium Nickel/Metal/Cobalt blends, or Lithium Nickel/Cobalt/Aluminum blends. Other types of anodes are also available, and one of the newest types is Lithium Titanate. All of these variations will have somewhat different voltage discharge curves, with some of the typical voltages shown here. Some of the combinations have lower voltage and correspondingly lower energy density. However these types of cells are optimized for very high peak power output, and also can be recharge cycled many hundreds or even thousands of times. So they are well suited for high power applications where cycle life is important.