In-situ Nano-Crystallization and Solvation Modulation to Promote Highly Stable Anode Involving Alloy/De-alloy for Potassium Ion Batteries

For advanced anode materials involving alloy/de-alloy chemistry for potassium ion batteries (PIBs), two-dimensional (2D) bismuth subcarbonate (BCO) nanosheets that possess high theoretical capacity of 631 mAh g(-1) are proposed. The large lattice spacing of 0.683 nm along b axis facilitate insertion of K+ ion to boost high-capacity delivery of ca. 610 mAh g(-1), and the in situ nano-crystallization well ease volume changes of the integrated particle and shorten ion diffusion path during potassiation/depotassiation. After coupling with a concentrated KFSI-G2 electrolyte, the robust and efficient SEI built from enhanced participation of FSI- synergistically endow structural stability of the flower-like BCO, and enable a prolonged cycling performance with capacity of ca. 300 mAh g(-1) at 0.2 A g(-1) for 1500 cycles, achieving an ultralow decay rate of 0.007 %. Mechanistic investigations probe the electrochemistry involving alloy/de-alloy and phase transition of the electrode.

Automated summary

The proposal of 2D bismuth subcarbonate nanosheets for advanced anode materials in potassium ion batteries shows improved capacity and cycling performance, with the ability to withstand numerous cycles at a low decay rate.