Structure‐Engineered Low‐Cost Carbon Microbelt Hosts for Highly Robust Potassium Metal Anode

Abstract Potassium metal as anode is an ideal material for the assembly of high specific energy batteries. However, safety issues caused by unrestricted dendrite growth and “dead K” generation severely limit their application. Here, based on the concept of waste recycling, a structural engineering strategy (chemical exfoliation and enzyme‐assisted synergistic method) is proposed to prepare oxygen‐containing functionalized porous carbon microbelts (OPCMs) as freestanding K metal hosts. The porous structure, uniformly distribution of carbon nanospheres, and the presence of oxygen‐containing functional groups reduce the energy barrier of K nucleation and promote the deposition kinetics. Benefitting from these advantages of OPCMs, the OPCMs‐based K composite anodes (K‐OPCMs) are free of obvious dendrite growth during the plating process. Symmetric cells assembled with K‐OPCMs maintain a stable overpotential of 40 mV after cycling for more than 800 h at 1 mA cm⁻². In addition, the K‐OPCMs//organic cathode (PTCDA) full cell exhibits excellent rate capability (96% capacity retention, 100–2000 mA g⁻¹, which is superior to most reported potassium metal batteries) and ultralong lifespan (97.8 mA h g⁻¹, after 1500 cycles at 2000 mA g⁻¹). This study illustrates the effectiveness of structure‐engineered and provides a guiding insight for achieving high‐performance rechargeable batteries.