Inside the Alloy Mechanism of Sb and Bi Electrodes for K-Ion Batteries

For a long time p-block elements such as Sb and Bi have stimulated the battery research community due to their interesting alloying/ dealloying processes in Li-ion as well as in Na-ion batteries. In fact, high capacity and good cyclability can be reached provided that an adapted electrode formulation is applied. Can we extend such electrochemical behavior and performance to potassium? K with a bigger atomic radius was ignored for a long time in spite of its low standard potential in conventional electrolyte and its low cost, which would make K-ion batteries excellent systems. The present study explores the potentiality of Sb and Bi electrodes in K-ion batteries and investigates the electrochemical mechanism occurring through operando XRD. The mechanism in Sb/K and Bi/K systems is then compared to those previously proposed for Li- and Na-ion batteries.