Uniform implantation of ultrafine Cu₂S nanoparticles into carbon nanowires for efficient potassium-ion battery anodes

Owing to their high capacities and abundant resources, transition metal sulfides (TMSs) have been proven attractive anode materials for potassium-ion (K-ion) batteries. Nevertheless, TMSs are usually limited by poor electrical conductivity and large volume expansion, leading to structural instability and inferior battery cyclability. Herein, we significantly alleviated the nanoparticle aggregation and pernicious structural degradation by embedding ultrasmall Cu₂S nanoparticles in carbon nanowires (Cu₂S@C NWs). The volume change in every NW was effectively accommodated compared with conventional Cu₂S particles, dramatically improving morphological integrity and leading to a noticeable enhancement in cycle life. As expected, the Cu₂S@C NW anode can deliver a large reversible capacity of 391.1 mA h g⁻¹, an excellent rate capability of 118.1 mA h g⁻¹ at 5 A g⁻¹, and a high-capacity retention of 77.2% after 500 cycles at 2 A g⁻¹. In addition, when the Cu₂S@C NW anode was assembled with the KVPO₄F/carbon nanotubes (CNTs) cathode to form a K-ion full cell, it showed a good discharge capacity of 110.8 mA h g⁻¹ after 100 cycles at 50 mA g⁻¹. This nanoparticle agglomeration-retardant strategy broadens the horizons for nanoengineering to release the stress induced by potassium (de)intercalation and facilitate the further development of efficient anodes for K-ion batteries. © 2023, Science China Press.