Preparation of air-stable and highly conductive potassium-intercalated graphite sheet

•Air-stable potassium–graphite intercalation compounds were easily prepared.•The compound had well staged structure.•Its electrical conductivity was about 10 times larger than that of host graphite.•The electrical conductivity of the compounds was comparable to that of iron.•The electrical conductivity of the compounds remained constant under open air.

Potassium–graphite intercalation compounds with chemical compositions of KC84, KC48, KC36 and KC8 were prepared from PGS graphite sheet and then treated with 6 M-HCl aqueous solution. After washing with water and drying under open air, chemical composition, stage structure and electrical conductivity of the resulting air-stable compounds were determined. It was found that about 40% of potassium in the starting potassium–graphite intercalation compounds remained in the matrix after treated with 6 M-HCl aqueous solution for KC84, KC48 and KC36, while 15% for KC8. The room temperature electrical conductivity of an air-stable compound, containing potassium of 0.008 in molar ratio of potassium to carbon, was determined to be 1.3×105 Scm−1. This is comparable to that of iron (1.0×105 Scm−1) and about 1/3 of that of aluminum (3.6×105 Scm−1).