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

Abstract

The rational architecture and composition of electrocatalysts are crucial factors for highly efficient lithium-oxygen (Li–O 2 ) systems. In this study, one-dimensional MnO 2 polymorphisms (α-, δ-, γ-MnO 2 ) and a hybrid nanostructure composed of α-MnO 2 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 α-MnO 2 , δ-MnO 2 , and γ-MnO 2 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 Li 2 CO 3 . Therefore, the incorporation of Ru nanoparticles on the surface of virus-templated α-MnO 2 nanowires is studied as an efficient carbon-free cathode material. Notably, the virus-templated Ru/α-MnO 2 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 −1 . 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. • An effective carbon-free cathode catalyst is developed. • The efficient catalysts are designed using filamentous M13 phage as a bio-template. • The virus-templated Ru/α-MnO 2 nanowires inhibit the side reactions occurrence. • The integrated gel polymer electrolyte/cathode enhances the cyclability of Li–O 2 .