Synthesis of nanosized nickel sulfide in high-boiling solvent for all-solid-state lithium secondary batteries

Nickel sulfidenanoparticles were synthesized by thermal decomposition of nickel acetylacetonate in a mixed solution of 1-dodecanethiol and a high-boiling solvent. The crystal phase and morphology of the obtained samples by changing the reaction time, reaction temperature, and the kind of the solvents were characterized by X-ray diffraction measurements and transmission electron microscopy. By using oleylamine as a coordinating solvent, Ni 9 S 8 nanorods with the size of about 100 nm were obtained at 280 °C for 5 hours. On the other hand, NiS nanoparticles with the size of about 50 nm were obtained by using 1-octadecene as a noncoordinating solvent. Nickel sulfide crystals with different phase and morphology were obtained by selecting the solvent. The all-solid-state cells using NiS nanoparticles with the size of about 50 nm as active materials were fabricated. The 80Li 2 S·20P 2 S 5 (mol%) glass-ceramic was used as a solid electrolyte. The cell Li-In/NiS exhibited the initial discharge capacity of 780 mA h g −1 at 0.13 mA cm −2 and the good cycle performance during 20 cycles. Nanosized NiS particles synthesized in a high-boiling solvent were used as an active material and all-solid-state Li-In/NiS cells with Li2S-P2S5 solid electrolytes exhibited an excellent cycling performance at room temperature.