Sb₂S₃-based conversion-alloying dual mechanism anode for potassium-ion batteries

The large volume expansion and sluggish dynamic behavior are the key bottleneck to suppress the development of conversion-alloying dual mechanism anode for potassium-ion batteries (PIBs). Herein, Sb₂S₃ nanorods encapsulated by reduced graphene oxide and nitrogen-doped carbon (Sb₂S₃@rGO@NC) are constructed as anodes for PIBs. The synergistic effect of dual physical protection and robust C-Sb chemical bonding boosts superior electrochemical kinetics and great electrode stability. Thus, Sb₂S₃@rGO@NC exhibits a high initial charge capacity of 505.6 mAh·g^-1 at 50 mA·g^-1 and a great cycle stability with the lifetime over 200 cycles at 200 mA·g^-1. Ex situ XRD, XPS, and TEM characterizations confirm that the electrode undergoes a multielectron transfer process (Sb₂S₃↔ Sb + K₂S ↔ KSb + K₃Sb), where K-ion insert into/extract from the material via dual mechanisms of conversion and alloying. This work sheds a light on the construction of high-performance anode materials and the understanding of K-ion storage mechanism.