Uniform potassium metal deposition under fast ion transportation kinetic: Porous carbon nanotube/metal–organic frameworks composite host

Abstract

Potassium Metal Batteries (KMBs) are emerging as favorable candidates for next-generation high-efficiency energy storage technologies, due to their impressive specific capacity, low redox potential, and the abundance of K. Nevertheless, challenges such as dendrite growth and considerable volume expansion have been hindering in their commercial utilization. Herein, a lightweight and self-supporting flexible three-dimensional (3D) composite host with porous metal–organic frameworks and carbon-nanotube (CNT@ZIF-8) is developed. The unique design of CNT@ZIF-8 composite host offers a multitude of potassiophilic N/Zn active nuleation sites, extensive surface area, and a porous structure. These features play a pivotal role in the management of K transport dynamics, facilitating K+ prestoring and predistribution. Benefiting from the narrowed concentration polarization and uniform nucleation, a dendrite-free K metal anode is constructed. The K@CNT@ZIF-8 anode demonstrates a remarkable durability, operating for 3200 h under 0.35 mA cm−2 and 0.35 mAh·cm−2 conditions, while also maintaining stability over 650 h at 1.0 mA cm−2 and 1.0 mAh·cm−2. Additionally, the full cell of PTCDA||K@CNT@ZIF-8 variant exhibits a boosted cycling stability (88 mAh g−1 at 5 C after 1000 cycles) and rate performance (98 mAh g−1 at 20 C). The results underscore the immense potential of CNT@ZIF-8 in facilitating practical applications for energy storage.