Boosting Efficient K-Ion Storage of Sb 2 S 3 -Based Conversion-Alloying Dual Mechanism Anode via Synergistic Effect of Physical Protection and Chemical Bonding

Conversion-alloying dual mechanism anode materials have become the research hotspot for potassium-ion batteries (PIBs) due to its high theoretical specific capacity and low operating voltage. However, the large volume expansion and sluggish dynamic behavior are still the key bottleneck to suppress its further development. 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 between Sb2S3 and graphene boosts superior electrochemical kinetics behavior and great electrode stability to buffer the huge lattice stress. As a result, Sb2S3@rGO@NC composite 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 multi-electron transfer process (Sb2S3 ↔ Sb + K2S ↔ KSb + K3Sb) based on the redox center of Sb-ion, 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.