Na2SnO3 as a novel anode for high performance lithium storage and its electrochemical reaction mechanism

Abstract Herein, Na 2 SnO 3 is employed as an anode for rechargeable lithium ion battery (LIB). We thoroughly investigated the electrochemical performance of Na 2 SnO 3 in comparison with the most commonly used Sn based oxides, such as SnO 2 and Li 2 SnO 3 . It is found that Na 2 SnO 3 is greatly superior to SnO 2 and Li 2 SnO 3 in terms of capacity, cycling stability and rate capability. Impressively, Na 2 SnO 3 presents favorable specific capacity of 480 mA h g −1 at current density of 200 mA g −1 after 100 cycles and still delivers a capacity of 439 mA h g −1 at extremely large current density of 1000 mA g −1 , which are leading the performance in anodes for LIBs. Ex situ SEM analysis of anodes after different cycles revealed the surface microstructure of anodes plays a critical role in determining cycling stability. The SEM results show big cracks on the surface of electrode for SnO 2 after less 15 cycles and for Li 2 SnO 3 after more 100 cycles, resulting from their severe volume change during charging-discharging process. However, Na 2 SnO 3 electrode exhibits uniform surface morphology after 100 cycles. It is concluded the “Na 2 O″ intrinsic matrix of Na 2 SnO 3 combining with “Li 2 O″ formed from the conversion reaction can act as a mixture buffering matrix that contributes to keeping the electrochemically formed nanoscale Sn particles apart and preventing their agglomeration during Li−Sn alloy formation and decomposition, thus inhibiting the volume expansion and the capacity fading by maintaining the electrode integrity. In addition, the electrochemical reaction mechanism of Na 2 SnO 3 with Li is investigated by ex situ XRD technique. The findings in this study provide a new valuable anode for high-performance LIBs and an insightful viewpoint of developing anode materials with high electrochemical performance by introducing the electrochemical inactive intrinsic matrix.