Method for producing lithium titanium phosphate

A method for producing a lithium titanium phosphate having a NASICON structure represented by the following general formula (1):

• Li1+xMx(Ti1−yAy)2−x(PO4)3 (1)
• wherein 0≤x≤1.0 and 0 ≤y≤0.5;
• M denotes one or two or more divalent or trivalent metal elements selected from Al, Ga, Sc, Y, La, Fe, Cr, Ni, Mn, In and Co;
• and A denotes one or two or more tetravalent or pentavalent metal elements selected from Ge, Zr, V, Nb, Sn and Si,
• the method comprising:
• a first step of preparing a raw material mixed slurry (1) comprising at least titanium dioxide, phosphoric acid, a polycarboxylic acid surfactant and a solvent;
• a second step of heat treating the raw material mixed slurry (1) to obtain a raw material heat-treated slurry (2);
• a third step of mixing the raw material heat-treated slurry (2) with a lithium source to obtain a lithium-containing raw material heat-treated slurry (3);
• a fourth step of subjecting the lithium-containing raw material heat-treated slurry (3) to a spray drying treatment to obtain a reaction precursor comprising at least Ti, P and Li;
• and a fifth step of firing the reaction precursor.