Synthesis of Nickel Titanite from Nickel Recovery from Spent Ni–MH Batteries

In this work, different synthesis routes from the anode and cathode of a spent nickel metal hydride (Ni-MH) battery were studied for the purpose of producing different ceramic precursors for the formation of nickel titanate (NiTiO3). The precursors were subjected to heat treatments at different temperatures to form NiTiO3, in which samples 1A and 2A were obtained from the anode and sample 1C from the cathode. The metal content of the Ni-MH battery’s active devices was determined by inductively coupled plasma optical-emission spectrometry. The contents were characterized by thermogravimetry, Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The FTIR spectra of samples 1A, 2A, and 1C heat-treated at 800 °C with a 2 h isotherm indicated the existence of two main absorption regions in all the samples: the first, at 525 cm–1, was attributed to Ti–O stretching, and the second, at 440 cm–1, to the Ti–O–Ni bond attributed to the formation of NiTiO3. The Raman spectra of all of the samples obtained through the heat treatment showed intense vibrational modes for NiTiO3. The diffractograms occurrence of NiTiO3 and TiO2 phases was identified in all samples, which is in agreement with the data files PDF #33–0960 (NiTiO3, nickel titanate) and PDF #21–1276 (TiO2, rutile), it is important to highlight that the bunsenite phase, according to PDF #47–1049 (NiO), was observed in samples 1A and 1C. All the synthesis routes were successful in forming NiTiO3 from the active material of the Ni-MH battery.