Batteries are on everybody’s mind these days. As smart devices evolve to perform more complex actions, the batteries that power those devices must hold up their end of the deal and provide sufficient charge time. Battery issues have plagued the newest release of the most popular smartphone in the world: the iPhone 4S.
Will the lithium-ion batteries of the future hold a charge for over a week and only take 15 minutes to fully recharge? According to engineers at Northwestern University, that reality is only 3 to 5 years away.
When creating their new super-lithium-ion battery, the researchers attempted to tackle two big problems of the technology – “energy capacity and charge rate.” Basically, how long the battery holds a charge and how quickly you can charge it back up from dead.
Lithium-ion batteries work through a reaction that sends ions back and forth between the battery ends, the anode and cathode, through the electrolyte. As of right now, lithium-ion batteries are limited by the charge density – or how full you can pack the ends with the ions. That affects how long the batteries last. They are also limited by how fast ions can travel from the electrolyte to the anode. That limits how fast they can be recharged.
Here is the current state of these batteries:
In current rechargeable batteries, the anode — made of layer upon layer of carbon-based graphene sheets — can only accommodate one lithium atom for every six carbon atoms. To increase energy capacity, scientists have previously experimented with replacing the carbon with silicon, as silicon can accommodate much more lithium: four lithium atoms for every silicon atom.
Except silicon is unstable during the charging process. The engineers have apparently fixed that issue:
To stabilize the silicon in order to maintain maximum charge capacity, they sandwiched clusters of silicon between the graphene sheets. This allowed for a greater number of lithium atoms in the electrode while utilizing the flexibility of graphene sheets to accommodate the volume changes of silicon during use.
So the addition of silicon allows for the batteries to hold a charge longer, lasting 10 times as long as current lithium-ion batteries. As far as the speed of the recharge is concerned, the team uses tiny holes to create “shortcuts” for the ions traveling back to the anode. This apparently reduces the recharge time tenfold.
iPhones, tablets, even electric cars could benefit from this research. Can you even imagine a world where your smartphone only needed a charge once a week and that charge only took a few minutes? Let us know in the comments.