Carbonaceous Skin-Optimized Reversibility of Bismuth- and Antimony-Based Selenide as an Ultrastable Anode for Potassium Ion Storage

Because of the abundant potassium reserves, low redox potential, and rocking chair mechanism similar to lithium-ion batteries, potassium ion batteries (PIBs) are highly attractive in the field of energy storage. Bi2Se3 is regarded as a desirable anode material for PIBs according to the large interlayer spacing and high theoretical capacity. Nevertheless, the electrochemical properties of Bi2Se3 are restricted by the poor reversibility of conversion reactions and huge volume fluctuation during the insertion and extraction of K+ ions. Herein, two-dimensional bismuth- and antimony-based selenide (Bi1.66Sb0.34Se3@C) is designed, with the incorporation of antimony to further elevate the specific capacity and carbonaceous skin to address the issue of irreversibility of conversion reactions. Bi1.66Sb0.34Se3@C achieves an admired potassium storage capability of 483.5 mA h g–1 under 0.1 A g–1, as well as a promising reversible capacity of 289 mA h g–1 at 2 A g–1. Owing to the robust carbonaceous skin, the reversibility of Bi1.66Sb0.34Se3@C is greatly improved, achieving reserved capacities of 372 mA h g–1 after 150 cycles under 0.2 A g–1 and 253 mA h g–1 at 1500th cycle under 1 A g–1. The mechanism of the optimized potassium storage performance is explored, and the tactic for achieving an ultrastable conversion-alloy-based anode for PIBs is proposed.