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

Abstract Several P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 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.