As an alternative to Li-ion batteries, K-ion batteries have attracted attention because of the abundant potassium reserves, low prices, and environmental friendliness of K resources. In the present work, using the first-principles calculations, we predict [n]phenacenes as promising intercalation-type anode materials for K-ion batteries that are superior to graphite.[n]Phenacenes have a small volume expansion ratio of <50% and a high theoretical specific capacity of >700 mAh/g during the K intercalation. The electron transfer upon the K intercalation results in a good electrical conductivity and a low average open-circuit voltage. Finally, the low diffusion barrier of K ions in [n]phenacenes implies a rapid charge/discharge rate performance. All these results suggest that aromatic [n]phenacenes are promising anode materials for K-ion batteries.

Solid methane doped by beryllium is superconducting at low pressures and its critical temperature can reach 30 K.

Because of the high voltage and low cost, potassium-ion batteries have become a hotspot in the research of rechargeable batteries. In this paper, the electrochemical properties of poly-p-phenylenes are studied based on first-principles calculations. Poly-p-phenylenes are predicted to be promising intercalation-type anode materials for potassium-ion batteries that are superior to graphite. The results show that potassium ions can intercalate into poly-p-phenylenes without significant phase change. The anode is predicted to have a small volume expansion ratio of <60% and a high theoretical specific capacity of >800 mA h/g. The electron transfer from potassium to organic molecules results in a good electrical conductivity and a low average open-circuit voltage. Additionally, the low diffusion barrier of potassium ions in poly-p-phenylenes implies a rapid charge/discharge rate performance. Our results suggest that poly-p-phenylenes are promising anode materials for potassiumion batteries.

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