| Summary: | A Ni(OH)2 surface was fluorinated at 25 °C using F2 gas for 1 h under absolute pressure of 6.67 kPa. Some fluorides and oxyfluorides were detected only on the Ni(OH)2 particle surface, although most Ni(OH)2 remained inside of the particles. Fluorine-introduced NiO (NiO(F)) was obtained by heating the surface-fluorinated Ni(OH)2. After sintering at 750 °C for 6 h, the NiO(F) crystal size and surface area were, respectively, 0.6 times smaller and 4.7 times larger than those of NiO obtained from untreated Ni(OH)2. LiNiO2 samples were prepared via reaction between NiO(F) and Li2CO3 at 700 °C for 20 h and 30 h, respectively (LiNiO2 (20 h, F) and LiNiO2 (30 h, F)). The density of LiNiO2 (30 h, F) was 4.697, which was larger than the 4.556 of LiNiO2 prepared from NiO and Li2CO3 under the same conditions. The discharge capacity of LiNiO2 (30 h, F) was 202 mAh g−1, whereas the LiNiO2 prepared under the same condition from NiO and Li2CO3 was 172 mAh g−1. The discharge capacity of LiNiO2 as a cathode of LIB might be improved by introducing fluorine to its preparation process between NiO and Li2CO3.
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