Prevention of side reactions with a unique carbon-free catalyst biosynthesized by a virus template for non-aqueous and quasi-solid-state Li-O2 batteries

The rational architecture and composition of electrocatalysts are crucial factors for highly efficient lithiumoxygen (Li-O-2) systems. In this study, one-dimensional MnO2 polymorphisms (alpha-, gamma-, -MnO2) and a hybrid nanostructure composed of alpha-MnO2 nanowires and Ru nanoparticles are designed through a bio-templated method. Their electrochemical properties are assessed as efficient electrocatalysts for a non-aqueous Li-O-2 cell. The virus-templated alpha-MnO2 , delta-MnO2, and gamma-MnO2 nanowires in combination with carbon additives indicate specific capacities of 10,875 mAh g(-1), 9726 mAh g(-1), and 6575 mAh g(-1), respectively. However, the presence of carbon inhibits the reversible reaction during cycling performance due to the formation of Li2CO3. Therefore, the incorporation of Ru nanoparticles on the surface of virus-templated alpha-MnO2 nanowires is studied as an efficient carbon-free cathode material. Notably, the virus-templated Ru/alpha-MnO2 hybrid electrode is delivered a high specific capacity of 14,383 mAh g(-1) with the stability of 48 cycles at a fixed capacity of 1000 mAh g . Meanwhile, lithium corrosion and electrolyte decomposition are observed during cycling, which restricts the life cycle of the cell. Therefore, a quasi-solid-state Li-O-2 cell is also fabricated by designing an integrated gel polymer electrolyte/cathode, and remarkably the Li-O-2 cell shows cycling up to 95 cycles.

Automated summary

The rational design of one-dimensional MnO2 polymorphisms and a hybrid nanostructure with Ru nanoparticles as efficient electrocatalysts for non-aqueous Li-O-2 cells is studied in this research. Incorporating Ru nanoparticles on virus-templated alpha-MnO2 nanowires showed high specific capacity and stable cycling performance, improving the efficiency of the Li-O-2 system.