Potassium-sulfur batteries in carbonate-based electrolytes cannot work well due to side reactions between polysulfide ions and ester molecules. Currently, removing superficial sulfur is an effective way to solve this issue. Here, we successfully achieved the deep encapsulation of sulfur and removal of superficial sulfur by a simple filtration-washing approach. As expected, the obtained products exhibited improved electrochemical stability and are promising candidates for better potassium-sulfur batteries.