NOVELTY - An olivine or sodium super ionic conductor (NASICON) type lithium transient metal phosphate material with mesoporous structure comprises mesoporous material which is secondary particles with nano-scale mesoporous pores formed from primary particles through conglobation.    USE - Olivine or sodium super ionic conductor type lithium transient metal phosphate material with mesoporous structure for lithium rechargeable batteries.    ADVANTAGE - The mesoporous structure material improves the rate performance and the energy density of existing positive material and battery and the rechargeable lithium battery containing such material has high power density and high safety.    DETAILED DESCRIPTION - An olivine or NASICON type lithium transient metal phosphate material with mesoporous structure comprises mesoporous material which are secondary particles with nano-scale mesoporous pores formed from primary particles through conglobation. Primary particles are pure-phase phosphate lithium metal phosphate (LiMPO4) with average particle diameter ranging of 10 nm-1 mu m or doped LiMPO4. The mesopores are formed among the primary particles. The chemical constitution of doped LiMPO4 is of formula LizAaMmBbPOxNn.    A=Na, Mg, Ti, V, Cr, Cu, Mn, Co, Ni, Zn, Ga, In or Ge;    M=Fe, Co, Mn, Ni or V;    B=Li, Na, K, Ca, Mg, Ti, V, Cr, Cu, Mn, Co, Ni, Zn, Ga, In or Ge, provided that M and B are not the same element at the same time;    x=0.9-1.8;    a=0.1-1;    m=0.5-1;    b=0-0.5;    z=3-4; and    n=0-1.    An INDEPENDENT CLAIM is included for preparing olivine or NASICON type lithium transient metal phosphate material with mesoporous structure involving preparing sol of pure-phase phosphate LiMPO4 by adding lithium salt, transient metal salt and phosphoric acid in solvent based on the molar ratio (1-1.1):1:(1-1.05), stirring the mixture for 0.5-1.5 hours to form the uniform solution, adding NH4.H2O to adjust pH value to 6-8 and continuously stirring until the sol is formed, preparing sol of doped phosphate LizAaMmBbPOzNn with mesoporous structure by adding transient metal salts based on the stoichiometric proportion, thermal processing to form dry gel by thermally processing the sol under air or inert atmosphere such as highly pure argon (Ar) or nitrogen (N2) gas at 60-200 degrees C until the sol is evaporated to dryness to oxidize, high temperature sintering by performing solid phase sintering in air or sintering in highly pure Ar, N2 or argon/ hydrogen mixed gas (Ar/H2) at 400- 900 degrees C for 3-48 hours and naturally cooling.