Widely used in laptop computers, digital cameras, and many other devices, lithium ion batteries store more energy for their weight, operate at a higher voltage, and hold a charge much longer than other rechargeable batteries. However, in some applications, such as hybrid electric vehicles, lithium ion batteries are limited by their poor ability to be quickly charged and discharged (as would be needed to capture the energy of a car when breaking). MRSEC researchers at MIT, in collaboration with scientists from the State University of New York at Stony Brook (SUNY), have modified the crystal structure of Li(Ni.5 Mn.5)O2, a material that exhibits high energy density but loses almost of all its storage capacity when charged quickly. The new re-engineered crystalline form of this material exhibits more than a ten-fold increase in its capacity under high rate conditions.The directed reengineering of this material was only possible through a combination of first principles modeling to identify the rate-limiting aspects of the structure, and the utilization of sophisticated characterization tools such as NMR and neutron diffraction. Because this material does not contain cobalt, a relatively expensive element present in current battery materials, it has the potential to be a safer, non-toxic and inexpensive battery material for use in hybrid electric cars.
