Stamped microbattery electrodes based on self-assembled M13 viruses

Abstract

The fabrication and spatial positioning of electrodes are becoming central issues in battery technology because of emerging needs for small scale power sources, including those embedded in flexible substrates and textiles. More generally, novel electrode positioning methods could enable the use of nanostructured electrodes and multidimensional architectures in new battery designs having improved electrochemical performance. Here, we demonstrate the synergistic use of biological and nonbiological assembly methods for fabricating and positioning small battery components that may enable high performance microbatteries with complex architectures. A self-assembled layer of virus-templated cobalt oxide nanowires serving as the active anode material in the battery anode was formed on top of microscale islands of polyelectrolyte multilayers serving as the battery electrolyte, and this assembly was stamped onto platinum microband current collectors. The resulting electrode arrays exhibit full electrochemical functionality. This versatile approach for fabricating and positioning electrodes may provide greater flexibility for implementing advanced battery designs such as those with interdigitated microelectrodes or 3D architectures.

Fig. 1.

Schematic procedure for constructing virus based microbattery electrodes. The virus-based cobalt oxide nanowires assembled on the polyelectrolyte multilayer were together stamped onto Pt microband current collectors.

Fig. 2.

Virus-based microbattery electrodes on PDMS stamp. (A) Height-mode AFM images of virus-based microbattery electrode on PDMS stamp (4-μm-diameter cylinders, pattern I) measured before the transfer to the current collectors. Z range is 2 μm. (B) Phase-mode AFM image of virus assembly before cobalt oxide growth. (C) AFM image of virus based microelectrode after cobalt oxide growth.

Fig. 3.

Self-assembled and stamped microbattery electrode based on the M13 viruses. (A) Image of microbatteries on the Pt current collector. (B) Optical microscopy image of the microbattery electrode (4-μm diameter) on four Pt microband current collectors (10-μm width). (C) SEM image of the stamped microbattery electrode.

Fig. 4.

Electrochemical testing of stamped microbatteries based on the M13 viruses (A) Charge-discharge curve for a virus assembled cobalt oxide microelectrode tested vs. Li/Li⁺, cell cycled between 3 and 0.01 V at a rate of 26 nA. (B) Capacity vs. cycle number for the same cell at six different charging currents. (C) Charge-discharge curve at a rate of 255 nA. A 2-h rest after charging and discharging in each cycle allows for cell equilibration. Stable cycling of the microbattery is exhibited.