Improving lithium storage of size-controllable nanostructured anatase, directed by an artificial protein genetically displayed on the surface of Escherichia coli

Abstract

Biomineralization-associated proteins are responsible for the structure-forming process of biominerals. Aiming to regulate the synthesis of nanostructured TiO2 anatase, an artificial protein 5R5 derived from silaffins was displayed on Escherichia coli surface through genetic manipulation. The genetically modified bacterial cells serve as the framework for the formation of rod-shaped TiO2, assembled by nanoparticles, as well as provide a carbon source in situ during the carbonization process. The particle size and carbon content were controllable by changing the heating temperature and time. The electrode annealed at 800 °C for 1 h shows the highest reversible capacity of 160.2 mA h g−1 after 200 cycles at a current rate of 1C. This unique nanostructured anatase not only shortens the diffusion pathway of lithium ions and electrons, but also improves the electric conductivity and tolerates the volume change during charging/discharging owing to carbon coating. However, the larger particle size and high carbon content were not advantageous to improve lithium storage performance.