TOBACCO MOSAIC VIRUS ENABLED SI ANODES AND LIFEPO4 CATHODES FOR LI-ION BATTERIES

摘要

The emerging fields of electric vehicles and renewable energies demand significant improvements in Li-ion battery technologies. To enhance the energy and power densities of Li-ion batteries, high capacity Si anodes and high power LiFePO4 cathodes, with long cycle life, were investigated. Self-aligned Si and LiFePO4 nanorods were fabricated on a genetically-modified Tobacco mosaic virus (TMV) template and shown both improved Li~+ and electronic conductance. Specifically, TMV templated Ni nanorods were directly attached to the main current collector in a near-vertical manner. The sequential layering of active materials creates a unique architecture where the highly conductive Ni layers act as nano-scale current collectors connecting the electrochemically active species covering each virus nanorod directly to the main current collector. TMV enabled Si nanorod anodes (Figure 1) [1-3] and LiFePO4 nanorod cathodes (Figure 3) demonstrated exceptionally high capacity and cycling stability. This composite silicon anode produced high capacities (3300mAh/g), excellent charge-discharge cycling stability (0.0% loss per cycle at 1C), and consistent rate capabilities (46.4% at 4C) between 0 and . V (Figure 2). Dense forests of LiFePO4 composite nanorods averaging of 500 nm diameter can deliver up to ～165 mAh/g at 0.C rate or ～ 105 mAh/g at 10 C rate, with no discernible capacity decay over 450 charge/discharge cycles at 1 C (Figure 4). This finding represents a significant performance improvement over previously reported LiFePO4-based cathode materials of similar nanosizes.