'Nanoscoop' Li-ion battery charges over 40 times faster

Scientists have developed a completely new nanomaterial that can offer recharge times for automotive batteries over 40 times faster than previously achievable, as well as opening up possibilities for th swift charging of mobile and laptop batteries.

The new generation of high power lithium (Li)-ion batteries, discovered by Professor Nikhil Koratkar at Rensselaer Polytechnic Institute, are expected to provide extremely high charge and discharge rates that causes the current incarnation of the Li-ion batteries to deteriorate quickly before failing to work at all.

The technology used is the new nanomaterial, dubbed ‘nanoscoop’ due to its resemblance to a scoop of ice cream, featuring a unique material composition, structure and size.

The research team at Rensselaer has successfully demonstrated how a nanoscoop electrode can be charged and discharged between 40 and 60 times faster than that of a conventional battery, managing to maintain this performance over 100 continuous charge cycles, opening the door for new high power, high capacity Li-ion rechargeable batteries.

“Charging my laptop or cell phone in a few minutes, rather than an hour, sounds pretty good to me,” said Koratkar. “By using our nanoscoops as the anode architecture for Li-ion rechargeable batteries, this is a very real prospect. Moreover, this technology could potentially be ramped up to suit the demanding needs of batteries for electric automobiles.”

Electric cars currently use supercapacitors to perform power-intensive functions, including starting the vehicle and rapid acceleration, in conjunction with conventional batteries that deliver high energy density for normal cruise driving and other operations. The researchers believe that nanoscoops may now enable these two separate systems to be combined into a single, more efficient battery unit.

According to the team at Rensselaer, the reason that contemporary batteries take so long to charge is that they are purposefully programmed to do so.  This is because the anode structure of a Li-ion battery physically grows, with discharging having the opposite effect, causing an amount of stress that will cause the battery to fail if done too quickly.  

Nanoscoop technology effectively relieves the need to protect against battery failure by intentional slowing down the charging.

The nanomaterial is constructed to withstand such a build up of stress, made with a carbon nanorod base topped with a thin layer of nanoscale aluminum (Al) and a ‘scoop’ of nanoscale silicon (Si).  Being engineered in this manner means that the nanomaterial is able to accept and discharge Li-ions at extremely fast rates  without sustaining damage.

It is the segmented structure of the nanoscoop that allows the strain to be gradually transferred from the C base to the Al layer, and finally to the Si scoop. This natural strain gradation provides for a less abrupt transition in stress across the material interfaces, leading to improved structural integrity of the electrode. 

The minute scale of the structure also lends strength to the material. “Due to their nanoscale size, our nanoscoops can soak and release Li at high rates far more effectively than the macroscale anodes used in today’s Li-ion batteries,” said Koratkar. “This means our nanoscoop may be the solution to a critical problem facing auto companies and other battery manufacturers – how can you increase the power density of a battery while still keeping the energy density high?”