High capacity and rate capability of a layered Li2RuO3 cathode utilized in hybrid Na+/Li+ batteries

Abstract

A novel hybrid Na⁺/Li⁺ battery is established by using Li₂RuO₃ as the cathode, 1 M NaClO₄ in 1 : 1 EC/PC solution as the electrolyte and metallic sodium as the anode. In the working voltages between 2.0 and 4.0 V, Li₂RuO₃ delivers a high discharge capacity of 168 mA h g⁻¹ under the current density of 0.1 A g⁻¹ and an excellent capacity retention of about 88.1% after 50 cycles. The cathode also exhibits superior rate capability and long-term cycle life, whose discharge capacity reaches 85 mA h g⁻¹ after 300 cycles at the current density of 1 A g⁻¹. Importantly, both Na⁺ and Li⁺ can reversibly intercalate/deintercalate into Li₂RuO₃ in the same manner as in the typical Li-ion half cell. In addition, ex situ X-ray diffraction patterns of the initial charge and discharge processes as well as after long electrochemical cycles are examined to study its structural evolution. Our studies provide a strong insight into the design and application of novel rechargeable batteries.