Ternary chalcogenide anodes for high-performance potassium-ion batteries and hybrid capacitors via composition-mediated bond softening and intermediate phase

Despite the high potassium-ion storage of chalcogenide anodes relative to intercalation-based graphite, inhibition of their large volume change during the potassiation/depotassiation process, and stabilization of reversible electrochemical reactions to ensure efficient electron/ion transfer remain challenging. Here we report composition-tunable ternary chalcogenides that achieve highly reversible potassium-ion storage through synergistic interactions between elements. A series of Bi2-xSbxSe3 ternary chalcogenide (x = 0, 0.25, 1, 1.75, 2) solid solutions with a full composition range are designed using a facile high energy mechanical milling method. Sb2Se3 substituted by Bi gives rise to a chemical bond softening effect that accompanies structural transition and maintains excellent structural stability. Meanwhile, the intermediate quaternary-phase K3(Bi,Sb)Se3 enables a highly reversible 12-electron transfer conversion/alloying reaction during the potassiation/depotassiation process. Various electrochemical analyses show that Bi2-xSbxSe3 inherits the advantages of binary Sb2Se3 (high capacity) and Bi2Se3 (stability) while balancing their respective disadvantages, confirming the synergistic effect of ternary chalcogenide systems. By engineering Bi2- xSbxSe3 implemented into potassium-ion based full cells, we demonstrate a high energy/power density of 76.9 W h kg- 1/1964.2 W kg- 1 for batteries and 54.3 W h kg-1/ 3685.7 W kg- 1 for hybrid capacitors. This work illustrates how to exploit the underlying multilateral science and the relevant electrochemistry of ternary chalcogenides to achieve excellent electrochemical performance, suggesting a new avenue of anode design for potassium-ion storage.

Automated summary

This study reports composition-tunable ternary chalcogenides that achieve highly reversible potassium-ion storage through synergy between elements. By using a combination of Bi and Sb, the ternary chalcogenide system demonstrates excellent structural stability and a reversible 12-electron transfer reaction during the potassiation/depotassiation process. The engineered ternary chalcogenides show high energy and power density in both batteries and hybrid capacitors. This work highlights the potential of ternary chalcogenides for anode design in potassium-ion storage.