Japanese FDK recently announced it has developed a new high-capacity lithium-ion battery, which is more durable than existing ones and is said to have a very short recharging time, although a specific charging time was not mentioned. It measures 18mm in diameter and 65mm in length, and has an energy density of 12 watt-hours per liter, which is claimed to be the world's highest among next-generation batteries. Charging the battery for five minutes allows a mobile phone to play ring tones for 25 minutes. FDK plans to start selling the battery in the spring of 2006.