Potassium ion storage has been given mushrooming attention and estimated the system could provide suitable energy density and low expense ascribed to the high operating potential and abundance of potassium source for deployment in grid-scale production and applications. Herein, we have designed and synthesized the ultrasmall SnSb encapsulated in disordered carbon matrix (SnSb@C) via a facile sol-gel approach. SnSb@C composites exhibited outstanding cycling lifetime with a demonstrated capacity of 200 mA h g-1 over 5000 cycles. A full battery assembled by coupling the SnSb@C anode with cathode (PTCDA) also showed an attractive electrochemical performance. We proposed and believed that this concept and work would give a fabrication direction to design large-scale and stable anodes for PIBs.