Chemical Prepotassiation Realizes Scalable KC8 Foil Anodes for Potassium‐Ion Pouch Cells.

Currently, graphite (Gr) and potassium metal are two typical and widely used anodes for potassium‐ion batteries (PIBs). Unfortunately, the inevitable electrochemical prepotassiation of Gr anode and the unprocessable nature of K metal hinder the advancement of potassium‐ion pouch cells. There is an urgent need to develop alternative anodes for promoting the practical applications of PIBs. Herein, KC8 is proposed as a specialized anode for the research of PIBs. By taking a chemical prepotassiation strategy, a large‐area KC8 foil is successfully fabricated for the first time. Through molecularly tailoring K‐arene complex, the Gibb's free energy of the Gr prepotassiation reaction can be changed, thus enabling accurate preparation of pure‐phase KC8.The size‐controllable KC8 anode exhibits a high areal capacity of 1.49 mAh cm−2 comparable to the commercial Gr anode used in lithium‐ion batteries. Based on this, a stackable pouch cell delivers an unprecedented high capacity of 106 mAh and high energy density >100 Wh kg−1cathode+anode. This work highlights the prospect of scalable KC8 foil anodes to achieve practical PIBs. [ABSTRACT FROM AUTHOR]