"You can change the molecular structure to pack in more active materials," he said. "Think of an hourglass. If you have finer grains of sand, you can put more in." Sony has also reduced the size of metallic components to increase space for active materials.
Lithium polymer, a battery gel material that can be shaped to fit efficiently inside phones or handhelds, has also grown in performance and popularity. One phone maker has completely converted to lithium polymer.
"People want slim phones. They don't want to go back to 10-millimeter cells," Chaudhury said.
Trouble ahead?
Problems, though, are brewing. For one thing, the end appears to be in sight for improvements to lithium ion. "The theoretical maximum will be reached by 2006 for lithium-ion chemistry," Chaudhury said.
Digital agenda
To continue to improve performance, device makers will begin to combine batteries with other technologies, such as superconductors and fuel cells. Toshiba has shown off a prototype fuel cell that it says can power an MP3 player for 20 hours. It may come out in 2006. Different types of fuel cells could be used to run laptops or televisions.
"That would truly be portable TV," said Fumio Ueno, an executive in the company's Display Devices & Components Control Centre.
Companies will still manage to eke improvements out of batteries, Chaudhury added. Another company, Japan's Pionics, is working on technology to increase the density of lithium ion, while Zinc Matrix Power is coming out with an alkaline battery in 2006 that it says could double the run time of notebooks.
Still, customers may never be fully satisfied. "Things (in notebooks) are going in the direction of greater power consumption," which could sap battery performance, said Roger Kay, an analyst at IDC.
Then again, Kay admits that he gets close to eight hours of battery life out of his notebook, thanks to a nine-cell battery in the back and a lithium-polymer battery in the DVD bay.
