Na2Ru0.8Mn0.2O3: A novel cathode material for ultrafast sodium ion battery with large capacity and superlong cycle life.

Abstract Sodium ion batteries have attracted special research interests world widely for large-scale electrical stationary applications due to the abundant reserve and wide distribution of Na element. However, most cathodes suffer from limited capacity, poor rate capability or inferior cycling stability, which cannot meet the requirements of high-performance sodium ion batteries. Thus, developing cathode materials with improved capacity, rate and cycling performance is in urgent demand. Herein, we design a series of Na 2 Ru 1-x Mn x O 3 using both cationic and anionic redox activities to achieve high capacity. Mn-doped Na 2 RuO 3 has been found to be capable of enhancing the oxygen redox activity, raising the redox potential, preventing the generation of spinel phase and moisture-sensitive phase upon charge process, facilitating charge transfer kinetics and suppressing the O3→P3 phase transition in a long cycle. As a result, Na 2 Ru 0.8 Mn 0.2 O 3 exhibits outstanding electrochemical performance by delivering a large capacity of over 90 mAh g−1 for long cycling of 1000 times at a high rate of 5 C. This study provides a prototype of high-performance ion-doped Na-rich cathode and could encourage scientists to explore more Na 2 MM'O 3 materials for ultrafast sodium ion batteries with large capacity and superlong cycle life. Graphical abstract Image 1 Highlights • A novel O3-type of cathode material was designed for high-performance SIBs. • The cathode shows excellent rate capability and high energy density (471 Wh kg−1). • The cathode mitigates O3→P3 phase transition upon cycling. • The cathode owns long-term cycling durability after 1000 cycles at ultrahigh rate. [ABSTRACT FROM AUTHOR]