MnO2-x nanosheets on stainless steel felt as a carbon- and binder-free cathode for non-aqueous lithium-oxygen batteries

•MnO2-x nanosheets were prepared with an electrodeposition-solvothermal route.•The nanosheets have high content of Mn(III) and oxygen vacancies.•A carbon-/binder-free cathode for Li–O2 batteries was made with MnO2-x nanosheets.•The cathode shows improved catalytic activity and good cycle stability.

Manganese dioxide (MnO2) has been recognized as an effective catalyst for the oxygen reduction and oxygen evolution reactions in non-aqueous lithium-oxygen batteries. However, a further improvement in battery performance with the MnO2 catalyst is limited by its low electronic conductivity and catalytic activity, which strongly depend on the morphology and composition. In this work, we develop a carbon- and binder-free MnO2-x nanosheets/stainless steel (SS) cathode via a simple and effective electrodeposition-solvothermal route. The created Mn(III) and oxygen vacancy in MnO2-x nanosheets allows an significant increase in the electronic conductivity and catalytic activity. It is experimentally shown that the use of the present nanostructure MnO2-x/SS cathode in a non-aqueous lithium-oxygen battery results in a rechargeable specific capacity of 7300 mAh g−1 at a current density of 200 mA g−1, which is 39% higher than that with the MnO2/SS cathode. In addition, the specific capacities at 400 mA g−1 and 800 mA g−1 reach 5249 mAh g−1 and 2813 mAh g−1, respectively, which are over 30% higher than that with the MnO2/SS cathode. Furthermore, the discharge/charge cycle test shows no degradation for 120 cycles. All the results show that the present nanostructure MnO2-x/SS cathode is a promising candidate for high-performance lithium-oxygen batteries.