Carbon quantum dots/carbon-coated SnS₂ as a high-performance potassium-ion battery cathode material

Potassium-ion batteries (PIBs) are considered to be an alternative to lithium-ion batteries because of their more affordable manufacturing cost and lower potential (2.936 V compared to standard hydrogen electrodes). However, the large ionic radius and unstable structure of potassium ions have hindered their satisfactory electrochemical performance from being satisfactory. In this study, a layered SnS₂@CQDs composite material was prepared using hydrothermal and pyrolysis methods as a promising anode material for PIBs. The composite material possessed a significant specific surface area, and the layered structure of SnS₂ contributed to its unique potassium-ion intercalation/deintercalation properties. The anchoring of the CQDs and carbon coating restricted the volume effect of SnS₂ and enhanced the electron transfer efficiency. PIBs prepared from this electrode exhibited a high potassium storage capacity (235 mA h g⁻¹ after 120 cycles at 100 mA g⁻¹) and excellent cycling stability (144.8 mA h g⁻¹ after 500 cycles at 500 mA g⁻¹).