Silver decorated beta-manganese oxide nanorods as an effective cathode electrocatalyst for rechargeable lithium–oxygen battery

• Ag/β-MnO2 was prepared by in-situ composite technique using polymeric additives.
• Ag/β-MnO2 can effectively improve the discharge capacity and the cycle life.
• Li2O is the main discharge product and no Li2CO3 is formed.

In this paper, Ag nanoparticles decorated β-MnO2 nanorods are studied as cathode catalyst for rechargeable lithium–oxygen battery (LOB). β-MnO2 nanorods are prepared using a simple hydrothermal method based on MnO4− and the decoration of Ag nanoparticles is performed by in-situ composite technique in the presence of polymeric additives. The as-prepared materials are characterized by XRD, TEM, XPS, BET and Raman spectrum. Electrochemical charging and discharging capacity of β-MnO2 and Ag/β-MnO2 electrodes are investigated at the current density of 0.02 mA cm−2 in the voltage window of 2.0–4.0 V. LOB with Ag/β-MnO2 electrode shows an initial discharge capacity of 873 mA hg−1(electrode), with reversible charge capacity of 811 mA hg−1(electrode) while battery with only β-MnO2 has discharge capacity of 541 mA hg−1(electrode) and charge capacity of 445 mA hg−1(electrode). Ag/β-MnO2 nanocomposite electrode shows good rate capability and cycle stability. After 10 cycles, the capacity of 742 mA hg−1(electrode) is still retained at the current density of 0.02 mA cm−2 while only 219 mA hg−1(electrode) is retained at 0.5 mA cm−2. The capacity retention rate is 84.9% and 70.2% at 0.02 and 0.5 mA cm−2, respectively. During discharging, Li2O is the main discharge product and no Li2CO3 is formed. The results show that the electrochemical performance of β-MnO2 is greatly enhanced when Ag nanoparticles are introduced. And it is highly effective for decreasing the charging potential close to the theoretical value. Ag nanoparticles can enhance the electronic conductivity of the network. The study confirms that Ag/β-MnO2 catalyst is a promising effective catalyst for LOB.