Synthesis and Characterization of Alginate-Based Sol–Gel Synthesis of Lithium Nickel Phosphate with Surface Area Control

A sol-gel method in which alginate was used to help prepare carbon-coated LiNiPO4 nanocrystal aggregate with controllable surface area is reported. Nickel alginate prepared from NiCl2 and sodium alginate was blended with stoichiometric LiOH and H3PO4 to produce a single source precursor gel. Calcining the gel in air at 400-800 oC produced LiNiPO4 nanocrystal aggregate with different levels of crystallinity, sizes and surface areas. PXRD, FESEM, HRTEM and BET analyses collectively showed that 600 oC was the optimal calcination temperature which gave LiNiPO4 with an average crystallite size of 43 nm and a surface carbon coating of 2-3 nm and a surface area of 27.47 m2/g. The method allows simultaneous achievement of four features, namely surface carbon coating, high crystallinity, control of primary particle size and high surface area. Simple modification of the method should allow the production of a wider range of LiMPO4 (M= Fe, Co, Mn).