To provide an unprecedented novel zirconium phosphate. A zirconium phosphate represented by Formula [1]: Zr(H.sub.a(NH.sub.4).sub.b(PO.sub.4))(HPO.sub.4).nH.sub.2O, wherein Ia/Ib is 1.0 or less where the maximum peak intensity in the range of 2θ=5 to 13° measured by the X-ray diffraction method is denoted by Ia and the maximum peak intensity in the range of 2θ=26 to 28° is denoted by Ib, and in Formula [1], a, b, and c are numbers satisfying a+b=1 and 0≤b<1, and n is a number satisfying 0≤n≤2.

The present disclosure discloses a cathode composite material for a lithium-ion battery (LIB), and a preparation method thereof. The cathode composite material for an LIB is composed of a lithium-containing matrix and a three-layer coating layer coated on a surface of the matrix, where the three-layer coating layer includes a lithium-deficient matrix material layer, a lithium-deficient lithium cobalt phosphate (LCP) layer, and a cobalt phosphate layer in sequence from inside to outside. The cathode composite material of the present disclosure can reduce the oxidation of a highly-delithiated cathode material to an electrolyte under high voltage, and has a high energy density.

A powder with particulates of a lithium ion-conducting material has a conductivity of at least 10.sup.−5 S/cm. The powder has an inorganic carbon content (Total Inorganic Carbon Content (TIC)) of less than 0.4 wt % and/or an organic carbon content (Total Organic Carbon Content (TOC)) of less than 0.1 wt %. The particulates have a d50 particle size in a range from 0.05 μm to 10 μm. The particulates have a particle size distribution log (d90/d10) of less than 4.

A powder with particulates of a lithium ion-conducting material has a conductivity of at least 10.sup.−5 S/cm. The powder has an inorganic carbon content (Total Inorganic Carbon Content (TIC)) of less than 0.4 wt % and/or an organic carbon content (Total Organic Carbon Content (TOC)) of less than 0.1 wt %. The particulates have a d50 particle size in a range from 0.05 μm to 10 μm. The particulates have a particle size distribution log (d90/d10) of less than 4.

A preparation method of a cathode material for a secondary battery is provided. First, a lithium metal phosphate material and a first conductive carbon are provided. The lithium metal phosphate material is made of a plurality of secondary particles. Each of the secondary particles is formed by the aggregation of a plurality of primary particles. An interparticle space is formed between the plurality of primary particles. Next, the lithium metal phosphate material and the first conductive carbon are mixed by a mechanical method, and a composite material is prepared. The first conductive carbon is uniformly arranged in the interparticle space. After that, a second conductive carbon, a binder and a solvent are provided. Finally, the composite material, the second conductive carbon, the binder and the solvent are mixed, and a cathode material for preparing a positive plate is prepared.

A hydrogel comprising a colloidal suspension of M.sup.I.sub.XM.sup.II.sub.YP.sub.Z two-dimensional nanocrystals in water, wherein M.sup.I is Na.sup.+ and/or Li.sup.+, M.sup.II is Mg.sup.2+ or a mixture of Mg.sup.2+ with one or more Ni.sup.2+, Zn.sup.2+, Cu.sup.2+, Fe.sup.2+ and/or Mn.sup.2+, P is a mixture of dibasic phosphate ions (HPO.sub.4.sup.2−) and tribasic phosphate ions (PO.sub.4.sup.3−). X ranges from about 0.43 to about 0.63, Y ranges from about 0.10 to about 0.18, Z ranges from about 0.29 to about 0.48, X, Y, Z being mole fractions, is provided.

A hydrogel comprising a colloidal suspension of M.sup.I.sub.XM.sup.II.sub.YP.sub.Z two-dimensional nanocrystals in water, wherein M.sup.I is Na.sup.+ and/or Li.sup.+, M.sup.II is Mg.sup.2+ or a mixture of Mg.sup.2+ with one or more Ni.sup.2+, Zn.sup.2+, Cu.sup.2+, Fe.sup.2+ and/or Mn.sup.2+, P is a mixture of dibasic phosphate ions (HPO.sub.4.sup.2−) and tribasic phosphate ions (PO.sub.4.sup.3−). X ranges from about 0.43 to about 0.63, Y ranges from about 0.10 to about 0.18, Z ranges from about 0.29 to about 0.48, X, Y, Z being mole fractions, is provided.

The present disclosure belongs to technical field of cathode materials of lithium batteries, and discloses a preparation method of high-safety high-capacity lithium manganese iron phosphate. The method includes the steps: (1) synthesizing a ferrous phosphate precursor through a co-precipitation process, and sintering to obtain an anhydrous ferrous phosphate precursor; (2) synthesizing a manganese phosphate precursor through co-precipitation process, and sintering to obtain an anhydrous manganese phosphate precursor; (3) adding lithium phosphate and deionized water into anhydrous ferrous phosphate precursor, and performing ball milling and wet sanding to obtain slurry A; (4) adding lithium phosphate, an organic carbon source, a dispersant, a dopant and deionized water into anhydrous manganese phosphate precursor, and performing ball milling and wet sanding to obtain slurry B; and (5) mixing slurry A with slurry B, and performing ball milling, spray drying, sintering and air jet pulverization to obtain high-safety high-capacity lithium manganese iron phosphate.

The present disclosure belongs to technical field of cathode materials of lithium batteries, and discloses a preparation method of high-safety high-capacity lithium manganese iron phosphate. The method includes the steps: (1) synthesizing a ferrous phosphate precursor through a co-precipitation process, and sintering to obtain an anhydrous ferrous phosphate precursor; (2) synthesizing a manganese phosphate precursor through co-precipitation process, and sintering to obtain an anhydrous manganese phosphate precursor; (3) adding lithium phosphate and deionized water into anhydrous ferrous phosphate precursor, and performing ball milling and wet sanding to obtain slurry A; (4) adding lithium phosphate, an organic carbon source, a dispersant, a dopant and deionized water into anhydrous manganese phosphate precursor, and performing ball milling and wet sanding to obtain slurry B; and (5) mixing slurry A with slurry B, and performing ball milling, spray drying, sintering and air jet pulverization to obtain high-safety high-capacity lithium manganese iron phosphate.

An objective of the present invention is to provide an all-solid-state battery with a high discharge capacity in which lithium vanadium phosphate is used as a positive electrode active material layer and a negative electrode active material layer. According to the present invention, the positive electrode active material layer and the negative electrode active material layer of the all-solid-state battery having an all-solid-state electrolyte between a pair of electrodes contain the lithium vanadium phosphate, the lithium vanadium phosphate contains a polyphosphate compound containing Li and V, and the lithium vanadium phosphate contains Li.sub.3V.sub.2(PO.sub.4).sub.3 as a main phase and contains 1.0% by weight or more and 15.0% by weight or less of Li.sub.3PO.sub.4 relative to Li.sub.3V.sub.2(PO.sub.4).sub.3, whereby a high discharge capacity can be provided.