Two-Dimensional TOD-Graphene in a Honeycomb–Kagome Lattice: A High-Performance Anode Material for Potassium-Ion Batteries

The giant delocalized π-electron system in pristine graphene is a double-edged sword; i.e., it gives rise to high electrical conductivity but results in chemical inertness. Therefore, graphene cannot be directly used as an anode for alkali metal-ion batteries due to its poor ion adsorption capacity. We propose a two-dimensional carbon allotrope (named TOD-graphene) with a combined kagome–honeycomb lattice. The robust energetic, dynamic, thermodynamic, and mechanical stabilities of TOD-graphene indicate the feasibility of the synthesis. The introduction of the kagome topology can disrupt the π-bonding network, thereby enhancing the surface reactivity. Its inherent metallicity and remarkable surface activity render TOD-graphene a promising anode material for high-performance potassium-ion batteries (PIBs). The TOD-graphene monolayer is characterized by high energy density (theoretical specific capacity of 1115.8 mA h g–1), good rate performance (diffusion barrier of 0.36 eV), and low output voltage (average open-circuit voltage of 0.52 V). In the presence of electrolytes, there is an apparent enhancement of K adsorption and diffusion capabilities. Moreover, bilayer TOD-graphene significantly affects both the adsorption strength and the mobility of K. These findings demonstrate that TOD-graphene is an excellent anode material for PIBs.