IRG-IV Highlight
Virus-grown battery materials
Figure. Top: Cartoon of a virus facilitating the growth of nanoparticles (inset shows an image of a virus decorated with FePO4·2H2O nanoparticles).
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Widely used in small electronic devices and in the nascent market for HEV (Hybrid Electric Vehicle), lithium ion batteries store more energy for their weight, operate at a higher voltage, and hold a charge much longer than other rechargeable batteries. As a new approach, Belcher and Ceder of the MIT MRSEC's IRG-IV have explored a biological way to create new charge storage materials for lithium ion batteries by using a virus as a scaffold to template the growth and assembly of nano scale electrode materials. The genetically engineered M13 virus (E4 virus) successfully provided a platform for the growth of amorphous iron phosphate, which can be used as a promising positive electrode material (Top Figure). For electrochemical testing of the obtained amorphous iron phosphate, silver nano rods, which were also grown on a separate E4 virus, were added as a conducting agent. Preliminary electrochemical data show that more than 120mAh/g of capacity can be delivered (the theoretical capacity of FePO4·2H2O is 140mAh/g). A small coin cell battery made from the virus-grown material powering an LED is shown in the Bottom Figure. Because of self-replication, virus growth of nanomaterials can be easily scaled up as an effective way to fabricate novel battery materials.
