Battery chemistry has undergone significant changes in recent years to meet the demands of the marketplace. Market drivers include increased power requirements and the desire for long battery life, coupled with the appeal of small size and weight. Another concern is reducing environmental impact. Lithium-ion batteries are a family of rechargeable battery types with high energy density both by weight and size. The casual battery user may think there is only one lithium-ion battery. However, there are actually several types, and new chemistries are being researched. The customer will choose the ideal battery chemistry/characteristic depending on the end application. The different chemistries have varying specific energy, specific power, safety, cost, life span, and performance.