JP3993394B2 - Olivine structure lithium nickel phosphate complex - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for the preparation of olivine-structured lithium nickel phosphate (LiNiPO ₄ ) composites that are very useful for high voltage lithium reversible batteries. LiNiPO ₄ is a useful reversible cathode material for high voltage lithium batteries in non-aqueous media.
[0002]
[Prior art]
All methods available from the literature have some drawbacks:
1. 1. Impure phase 2. relatively long heat preparation period 3. High temperature operation 4. pH control Multiple preparation steps
[Problems to be solved by the invention]
The main object of the present invention is to synthesize olivine LiNiPO ₄ by a suitable solid state reaction method. This method overcomes the disadvantages and limitations known in other methods of preparing this complex known in the literature and the like.
[0004]
[Means for Solving the Problems]
Accordingly, the present invention provides a method for preparing olivine-structured lithium nickel phosphate complexes. This method mixes Ni and P oxides uniformly with Li ₂ CO ₃ and pastes the mixture by adding glycerol, calcining the paste to 750 ° C. continuously for 12 hours, Obtaining the desired complex.
[0005]
In one aspect of the invention, the phosphorus oxide is P ₂ O ₅ .
In a further aspect of the invention, the nickel oxide is NiO.
In another aspect of the invention, the calcination is performed in a furnace.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The prepared product was subjected to x-ray analysis. The product was found to be a single phase. The olivine lithium nickel phosphate complex is prepared by mixing nickel and phosphorus oxides with lithium carbonate and heating them all together in solid state conditions.
[0007]
A cathode material for a secondary battery is prepared by heating a paste prepared by mixing fine particles of Li ₂ CO ₃ , P ₂ O ₄ and NiO in glycerol. This paste was first slowly heated in an oven to evaporate the glycerol, thereby obtaining a material dried at 250 ° C. The dried material was then continuously heated at 750 ° C. for 12 hours. The resulting composite was slowly cooled to room temperature, ground well, and its particle size, color and x-ray diffraction were measured. The prepared sample was purple and found to be uniform. As shown in FIG. 1, x-ray analysis confirmed the production of LiNiPO ₄ .
[0008]
The following example shows a method for synthesizing LiNiPO ₄ .
[0009]
Reference example 1
A 1: 1: 1 molar ratio of Li ₂ CO ₃ , NiO and P ₂ O ₅ (0.74 g, 1.49 g and 1.42 g, respectively) was slowly mixed in a glycerol binder (2 ml). Heat was heated to a temperature of 800 ° C. over a period of up to 10 hours while slowly adding flux (2.402 g of urea). The mixture was then cooled to room temperature and the residue was measured for x-ray diffraction. The purple product confirmed the formation of olivine lithium nickel phosphate (LiNiPO ₄ ) complex. The efficiency of the reaction was 90% and the product was obtained in a single phase. The single electrode potential of LiNiPO ₄ versus Li of 1M LiClO _{4 in} propylene carbonate was 2.99V.
[0010]
Example 1
A 1: 1: 1 molar ratio of Li ₂ CO ₃ , NiO and P ₂ O ₅ (0.74 g, 1.49 g and 1.42 g, respectively) was slowly mixed in a glycerol binder (3 ml). Heat was heated to a temperature of 600 ° C. over a period of up to 12 hours while slowly adding flux (2.402 g of urea). The mixture was then cooled to room temperature and the residue was measured for x-ray diffraction. The purple product confirmed the formation of olivine lithium nickel phosphate (LiNiPO ₄ ) complex. The efficiency of the reaction was 90% and the product was obtained in a single phase. The single electrode potential of LiNiPO ₄ versus Li of 1M LiClO _{4 in} propylene carbonate was 2.99V.
[0011]
The advantages of the present invention are as follows:
1. Reactants, ie fine particles of Li ₂ CO ₃ , NiO and P ₂ O ₅ , are combined by glycerol, and the mixture is made into a paste that reacts uniformly during heating.
2. Glycerol is used as a binder for inorganic solid state reactants.
3. As shown by the x-ray analysis results, the product LiNiPO ₄ is obtained as a single-phase component free of impurities.
4). All reactants react uniformly so that there are no unreacted initial reactant components.
5). Adding glycerol as a binder does not affect the production of the final product.
6). A homogeneous mixture of phosphorus oxide (P ₂ O ₅ ) and nickel oxide and Li ₂ CO ₃ is pasted to obtain a high purity product.
7). Glycerol, which is used as a solvent for the binding of oxides, ie phosphorus and nickel oxides, and Li ₂ CO ₃ to make the required consistency paste, also helps to make the product fine particles .
8). Glycerol (solvent) added in excess as a binding material for the oxide and flux added (urea) do not change the color and quality of the final product.
[Brief description of the drawings]
FIG. 1 is an x-ray analysis result confirming that LiNiPO ₄ has been formed.

Claims (4)

Ni and P oxides and Li ₂ CO ₃ are mixed uniformly, the mixture is made into a paste by adding glycerol, the paste is calcined and continuously added for up to 12 hours with urea added as a flux. A method for producing a olivine-structured lithium nickel phosphate complex, comprising bringing the desired complex to a temperature of up to 600 ° C. The method according to claim 1, wherein the phosphorus oxide is P ₂ O ₅ .   The method of claim 1, wherein the nickel oxide is NiO.   The method of claim 1, wherein the calcination is performed in a furnace.

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