On the use of guanidine hydrochloride soft template in the synthesis of Na2/3Ni1/3Mn2/3O2 cathodes for sodium-ion batteries

• Published in: Journal of alloys and compounds 2019-06, Vol.789, p.1035-1045
• Main Authors: Aragón, M.J., Ortiz, G.F., Lavela, P., Tirado, J.L., Oliveira, J.D.C., Motta, F.V., Bomio, M.R.D.
• Format: Article
• Language: English
• Subjects: Cathode; Crystallites; Diffraction patterns; Electrodes; Electrolytes; Electrolytic cells; Guanidine hydrochloride; Layered oxides; Morphology; Phase transitions; Rechargeable batteries; Sodium-ion batteries; X-ray diffraction
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.03.093

Several P2-Na2/3Ni1/3Mn2/3O2 layered oxides have been prepared by a modified synthesis procedure using guanidine hydrochloride as a soft template. X-ray diffraction patterns will reveal a decrease of both crystallite size and strain for guanidine hydrochloride treated samples, favoring sodium accessibility at the electrode/electrolyte interface. Also, guanidine hydrochloride promotes anisotropic particles for intermediate amounts. This specific morphology may contribute to a partial suppression of the P2-O2 phase transition. Galvanostatic tests at different rates and potential windows will evidence better capacity retention and low charge-discharge hysteresis for NaNMO-2% in close relationship with the low internal resistance values at the electrode-electrolyte interphase and apparent diffusion coefficients determined by impedance spectroscopy. A performing full sodium-ion cell will demonstrate the reliability of this material as an electrode for Na-ion cells. [Display omitted] •P2-Na2/3Ni1/3Mn2/3O2 was prepared using guanidine hydrochloride as a soft template.•Samples with intermediate guanidine content feature better capacity retention.•Their kinetic improvement is due to low impedances and high diffusion coefficient.•A full cell delivered an energy density of 210 W h kg−1 after discharging at C/20.