Virus-Enabled 3D Electrodes with Rapid Electronic Charge Transport

For 3D battery electrodes exhibiting extremely high rate capability (several hundred C), it is necessary to engineer rapid electronic conduction through the active matrix. In order to achieve this, we present a novel and highly tunable system employing an engineered M13 bacteriophage virus as a template for lithium-ion battery positive and negative electrodes. Genetically modified viruses are first cross-linked in order to form a hydrogel, then an electroless deposition process is used to form biotemplated nanoscale networks.  We demonstrate control over the geometry of these networks viagenetic manipulation of the virus and through processing conditions, engineering tunable nanostructures with pore sizes and strut widths making them amenable for use as 3D current collectors.  These networks are shown to be highly conductive, to retain a nanoporous architecture following heat treatments in excess of 450°C, and to be mechanically flexible. After fabricating such biotemplated nanostructures, both positive and negative electrodes were produced through subsequent processing steps. Electrodeposition was used to deposit manganese oxide onto nickel and tin was deposited onto copper through galvanic displacement, demonstrating the compatibility of these biotemplated current collectors with a wide range of active materials. Furthermore, as M13 bacteriophage have been engineered in our lab to bind a wide range of inorganic materials, the use of this surface functionality to directly embed active material particles into metallic current collectors is being explored. The high degree of control over nanostructural morphology inherent to this fabrication method combined with the mechanical flexibility of the resulting electrodes is expected to enable novel strategies for the integration of biotemplated batteries into vehicles ranging in size from automobiles to micro-robots.

Figure 1 (attached): Nanoporous nickel current collector fabricated through M13 virus-based biotemplating process