Dual‐Gradient Engineering of Conductive and Hierarchically Potassiophilic Network for Highly Stable Potassium Metal Anode.

Potassium (K) metal anodes are the most competitive candidates for low‐cost and high‐energy density rechargeable batteries. However, uncontrolled K dendrite growth strictly impedes the practical application of K metal anodes. Herein, a potassiophilic and conductive dual‐gradient free‐standing host (named TS‐PKS) composed of the bottom layer with Ti3CN and F doped SnO2 (F‐SnO2) and the top layer with perfluorinated sulfonic acid K (PFSA‐K) and ordered mesoporous silica (SBA15) is constructed to achieve dendrite‐free K deposition. The potassiophilicity and conductivity of the TS‐PKS host increase along with the depth direction to generate a bottom‐up dual‐gradient of K+ affinity and electroconductivity. Such bottom‐up dual‐gradient of K+ affinity and electroconductivity can synergistically manipulate uniform K metal deposition following the bottom‐up manner, preventing the notorious K dendrite growth. As a result, the TS‐PKS@K symmetric cell can stably cycle over 2800 h at 0.5 mA cm−2/0.5 mAh cm−2. Meanwhile, the TS‐PKS@K//PTCDA full battery also exhibits an initial specific capacity of 118.3 mAh g−1 at a high current density of 500 mA g−1 and maintains up to 81.1 mAh g−1 after 1000 cycles. This novel dual‐gradient strategy design offers a straightforward approach to effectively manipulate K metal deposition manner for achieving dendrite‐free K metal anodes. [ABSTRACT FROM AUTHOR]