MnO_2-x nanosheets on stainless steel felt as a carbon- and binder-free cathode for non-aqueous lithium-oxygen batteries

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 MnO_2-x nanosheets/stainless steel (SS) cathode via a simple and effective electrodeposition-solvothermal route. The created Mn(III) and oxygen vacancy in MnO_2-x nanosheets allows an significant increase in the electronic conductivity and catalytic activity. It is experimentally shown that the use of the present nanostructure MnO_2-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 MnO_2-x/SS cathode is a promising candidate for high-performance lithium-oxygen batteries.