But aside from tiny incremental improvements in solid-electrolyte efficiency, lithium ion polymer batteries for handheld tech products haven't changed drastically in more than 15 years. Almost all of the batteries that power today's smartphones and tablets run on some variant of the lithium ion polymer battery--a cell in which the anode and the cathode are packaged with a solid, gel-like electrolyte (the substance that makes the battery conduct electricity). This solid-electrolyte design was developed commercially in 1996 as manufacturers sought a sturdier battery for mobile tech products. Previously, cell phones had run on lithium ion batteries with liquid electrolytes, which were bulky and relatively unstable.
Today, battery researchers continue to increase the capacity of lithium ion polymer batteries. Since a battery's power comes from its transfer of electric-charge-bearing electrons between the anode and the cathode, battery researchers focus primarily on optimizing the multitude of mini-transfers. "A lot of chemical reactions can take on a life of their own, and battery scientists try to control that," said Irving Echavarria of Gold Peak Industries, a company that manufactures all types of consumer batteries, including lithium ion variations. Echavarria estimates that 80% of the processes in a battery can be accurately harnessed. And the smaller the battery's window of errant chemical reactions, the more efficiently the battery will provide power. Battery makers continue to achieve capacity gains by pushing closer to that 80% efficiency limit.
But the incremental advances in efficiency aren't keeping pace with the increasing energy demands of smartphones and other mobile devices. Frustrated by the chemical and physical limits of batteries, developers who want to get longer run times out of smartphone batteries must either add active material to the battery by making the inactive parts of the battery smaller (a technique that has already reached limits of its own) or move from lithium ion polymer to a different, as yet not fully researched material.
Venkat Srinivasan, a battery technology researcher at the Lawrence Berkeley National Laboratory in Berkeley, California, notes that, "the physics that dictates evolution in batteries is different from the physics that dictates evolution in smartphone electronics." It seems that batteries are doomed to drag along behind the wagon train until a Eureka moment happens occurs with a better material.
New Ideas Coming, Slowly
Small signs of innovation are visible on the battery-life horizon. The unanswered questions are how quickly they'll emerge, and whether the technology involved will be scalable to serve the entire mobile world.