No abstract

Nickel orthophosphate, Ni 3 (PO 4) 2 , was successfully synthesized using solid-state reaction at 900°C. The effect of the calcination temperature on the material purity was investigated at different temperatures (700-900°C). XRD analysis has shown that Ni 3 (PO 4) 2 crystallizes in a monoclinic system with P2 1 /a space group. The electrochemical performances of carbon-coated Ni 3 (PO 4) 2 were investigated for the first time versus Li + /Li and improved by the optimization of the cutoff voltage, the carbon-coating source, and the binder used. The best performance was delivered when using 0.01 V cutoff voltage, sucrose for C-coating, and carboxymethyl cellulose (CMC) binder. A reversible capacity of 249 mAh g À 1 and a capacity retention around 74-79 % after 90 cycles with a good coulombic efficiency of 98 % were obtained at C/5 current rate. In situ XRD measurements demonstrated the irreversible amorphization of the Ni 3 (PO 4) 2 crystal structure during the first discharge process, confirming that this phosphate exhibits a pure conversion mechanism.