Understanding the Formation of a Cubic Mn0.6fe0.4s Solid-Solution Anode and its High Performance for Rechargeable Lithium-Ion Batteries

Solid solution materials show promising performance for applications in rechargeable lithium-ion batteries, but their synthesis and conversion mechanism are still quite a difficult task that needs to be tackled. Herein, a cubic Mn 0.6 Fe 0.4 S solid solution based on conversion reactions is successfully synthesized by a scalable in situ sulfuration treatment of Prussian-blue analogue, and its phase formation process and Li-storage mechanism is investigated. A further increase in treatment temperature and time promotes the phase transformation from hexagonal Fe 7 S 8 to cubic FeS 2 during sulfuration process, which result in formation of solid solution between cubic FeS 2 and cubic MnS. Meanwhile, the Mn 0.6 Fe 0.4 S solid solution electrode exhibits high initial coulombic efficiency, excellent rate performance and superior cycling stability (520 mA h g −1 after 1000 cycles at 1.0 A g -1 ) . This study is further demonstrated by ex-situ X-ray diffractometer and electro-kinetics test that the doping-induced structural phase transition in Mn 0.6 Fe 0.4 S solid solution could create a favorable electronic structure and ensure rapid charge transfer kinetics during the lithiation/delithiation process, thus achieving high energy conversion efficiency and considerable lifespan simultaneously