Unveiling the Nature of Ultrastable Potassium Storage in Bi0.48Sb1.52Se3 Composite

The conversion and alloying-type anodes for potassium-ionbatteries(PIBs) have drawn attention. However, it is still a challenge to relievethe huge volume expansion/electrode pulverization. Herein, we synthesizeda composite material comprising Bi0.48Sb1.52Se3 nanoparticles uniformly dispersed in carbon nanofibers(Bi0.48Sb1.52Se3@C). Benefiting fromthe synergistic effects of the high electronic conductivity of Bi0.48Sb1.52Se3 and the mechanical confinementof the carbon fiber that buffers the large chemomechanical stress,the Bi0.48Sb1.52Se3@C//K half cellsdeliver a high reversible capacity (491.4 mAh g(-1), 100 cycles at 100 mA g(-1)) and an extraordinarycyclability (80% capacity retention, 1000 cycles at 1000 mA g(-1)). Furthermore, the Bi0.48Sb1.52Se3@C-based PIB full cells achieve a high energy densityof 230 Wh kg(-1). In situ transmissionelectron microscopy (TEM) reveals an intercalation, conversion, andalloying three-step reaction mechanism and a reversible amorphoustransient phase. More impressively, the nanofiber electrode can almostreturn to its original diameter after the potassiation and depotassiationreaction, indicating a highly reversible volume change process, whichis distinct from the other conversion type electrodes. This work revealsthe stable potassium storage mechanisms of Bi0.48Sb1.52Se3@C composite material, which provides aneffective strategy to enable conversion/alloying-type anodes for highperformance PIBs for energy storage applications.

Automated summary

The researchers synthesized a composite material consisting of Bi0.48Sb1.52Se3 nanoparticles uniformly dispersed in carbon nanofibers (Bi0.48Sb1.52Se3@C), which exhibited high capacity and cycling stability for potassium-ion batteries. The study reveals the stable potassium storage mechanisms of the Bi0.48Sb1.52Se3@C composite material, providing an effective strategy for high-performance potassium-ion batteries for energy storage applications.