Stability of the electrical resistivity of bromine, iodine monochloride, copper(II) chloride, and nickel(II) chloride intercalated pitch-based graphite fibers

Abstract

Four different grades of pitch-based graphite fibers (Amoco P-55, P-75, P-100, and P-120) were intercalated with each of four different intercalates: bromide (Br 2), iodine monochloride (ICI), copper(II) chloride (CuCl 2), and nickel(II) chloride (NiCl 2). The P-55 fibers did not react with Br 2 or NiCl 2, and the P-75 did not react with NiCl 2. The stability of the electrical resistance of the intercalated fibers was monitored over long periods of time in ambient, high humidity (100% at 60°C), vacuum (10 −6Torr), and high temperature (up to 400°C) conditions. It was found that fibers with lower graphitization form graphite intercalation compounds (GICs) that are more stable than those with higher graphitization (i.e., P-55 (most stable) > P-75 > P-100 > P-120 (least stable)). Br 2 formed the most stable GICs followed in order of decreasing stability by ICI, CuCl 2, and NiCl 2. Although Br 2 GIC's had the best stability, ICI had the advantages of forming GICs with slightly greater reduction in resistance (by about 10%) than Br 2, and the ability to intercalate P-55 fiber. The transition metal chlorides appear to be seriously susceptible to water vapor and high temperature.