What are the advantages of lithium ion batteries?

When compared with conventional Lead acid, Nickel Cadmium or Nickel metal hydride batteries, lithium ion batteries have major advantages:

• Considerably higher voltage
• High capacity and power rating at low weight and volume (3 – 5 fold energy and power density)
• Extremely high cycle stability also at full depth of discharge with an outstanding lifetime
• Low self-discharge
• No memory effect
• Maintenance free