Hybrid nanostructure designs facilitated by M13 virus for lithium ion battery and lithium air battery electrodes

Abstract

The development of technology and population growth will demand 56 percent increase of the energy consumption in 30 years. An efficient energy storage system will be necessary to meet these increased needs to deliver and store the energy. After the first release of commercial Li ion batteries in 1991, they were widely adapted to various applications from small portable devices to electric vehicles. However, the current Li ion battery can only store -250 Wh/kgcell of gravimetric energy, a far limited energy storage capability especially to replace gasoline in powering vehicles. This limitation originated either from the incomplete utilization of active materials or their low theoretical energy density. Therefore, a rational design of electrodes as well as the new battery chemistry needs to be investigated to further develop the current energy storage system. In this thesis, high theoretical energy density batteries are investigated. First, the power performance of conversion reaction cathode materials, bismuth oxyfluorides, was improved. By rationally designing genetic sequences of the M13 virus, graphene sheets were homogeneously distributed throughout bismuth oxyfluorides cathodes as conducting paths. Second, large surface area cathodes were developed with virus-templated manganese oxide nanowires. These electrodes were applied to Li-0₂ battery systems to achieve large capacities and a long cycle life. Furthermore, the chemical composition of virus-templated inorganic nanowires was easily tuned to study the catalytic behavior of transition metal oxides in Li-0₂ batteries. These bio-directed methods to develop high performance battery electrodes, in conclusion, suggest an eco-friendly and cost effective way to manufacture energy storage devices. The design strategy established in this thesis could be applied not only to batteries but also to electronic devices requiring sophisticated nanoscale controls.