Mixed ion phosphate positive electrode material and preparation method thereof

A positive electrode material and mixed ion technology, which is applied in the field of mixed ion phosphate positive electrode material and its preparation, can solve problems such as hindering the extraction and insertion of Li ions, reducing theoretical capacity, and reducing Li ions, so as to improve conductivity and electrochemical activity , Improve the discharge specific capacity, and the effect of easy control of the shape

Active Publication Date: 2015-07-01
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

And for other cathode materials with different Li occupations, such as Li 3 V 2 (PO 4 ) 3 and Li 9 V 3 (P 2 o 7 ) 3 (PO 4 ) 2 , the replacement of some Li sites by alkali metal ions (such as Na) may not hinder the extraction and intercalation of Li ions, but it is rarely reported in the literature that some Li sites are completely replaced by alkali metal ions
For Li 3 V 2 (PO 4 ) 3 For positive electrode materials, the three Li ions can basically be reversibly deintercalated. Although the substitution of alkali metals does not hinder the diffusion of Li ions, it will reduce the number of Li ions participating in the redox reaction, thereby reducing its theoretical capacity. However, Li 9 V 3 (P 2 o 7 ) 3 (PO 4 ) 2 Cathode materials do not have similar problems

Method used

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  • Mixed ion phosphate positive electrode material and preparation method thereof
  • Mixed ion phosphate positive electrode material and preparation method thereof
  • Mixed ion phosphate positive electrode material and preparation method thereof

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Experimental program
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Effect test

Embodiment 1

[0037] A kind of preparation method of mixed ion phosphate cathode material of the present embodiment, specific preparation steps are as follows:

[0038] (1) Mixed grinding: LiOH, NaOH, VO 2 and (NH 4 ) 3 PO 4 Weigh according to the elemental molar ratio of Li:Na:V:P=8:1:3:8 (LiOH: 1.155g, NaOH: 0.241g, VO 2 : 1.500g, (NH 4 ) 3 PO 4 -: 7.190g), using a planetary ball mill for 4 hours to obtain a precursor mixture;

[0039] (2) Pretreatment: Pretreat the precursor mixture in step (1) at 400°C for 10 hours in an air atmosphere, and then grind it again after cooling in the furnace to obtain a powdery intermediate product;

[0040] (3) Sintering reaction: The powdery intermediate product in step (2) was sintered at 700°C for 72 hours in a hydrogen atmosphere to obtain the mixed ion phosphate cathode material Li 8 NaV 3 (P 2 o 7 )3 (PO 4 ) 2 .

[0041] The XRD pattern of the product is shown in figure 1 In (a), it can be seen from the figure that the pure-phase mixe...

Embodiment 2

[0043] A kind of preparation method of mixed ion phosphate cathode material of the present embodiment, specific preparation steps are as follows:

[0044] (1) Mixing and grinding: Li 2 CO 3 、Na 2 CO 3 , NH 4 VO 3 and (NH 4 ) 2 HPO 4 Take by weighing the element molar ratio of Li:Na:V:P=7:2:3:8 (Li 2 CO 3 : 2.211g, Na 2 CO 3 : 0.906g, NH 4 VO 3 : 1.500g, (NH 4 ) 2 HPO 4 : 4.5156g), the raw material is ball-milled for 4h in a planetary ball mill to obtain a precursor mixture;

[0045] (2) Pretreatment: pretreat the precursor mixture in step (1) in an argon atmosphere at 300° C. for 5 hours, and after natural cooling, ball mill again to obtain a powdery intermediate product;

[0046] (3) Sintering reaction: The powdery intermediate product in step (2) was sintered at 600°C for 20 hours under a hydrogen atmosphere to obtain the mixed ion phosphate cathode material Li 7 Na 2 V 3 (P 2 o 7 ) 3 (PO 4 ) 2 .

[0047] The XRD pattern of the product is shown in ...

Embodiment 3

[0049] A kind of preparation method of mixed ion phosphate cathode material of the present embodiment, specific preparation steps are as follows:

[0050] (1) Mixing and grinding: CH 3 COOLi, CH 3 COONa, V 2 o 5 and NH 4 h 2 PO 4 Weigh (CH 3 COOLi: 2.177g, CH 3 COONa: 1.353g, V 2 o 5 : 1.500g, NH 4 h 2 PO 4 : 5.0594g), the raw material is ball milled in a planetary ball mill for 4h to obtain a precursor mixture;

[0051] (2) Pretreatment: the precursor mixture of step (1) is mixed in Ar-H with a volume ratio of 93:7 2 In a mixed gas atmosphere, pretreatment was carried out at 350°C for 2 hours, and after natural cooling, ball milling was performed again to obtain a powdery intermediate product;

[0052] (3) Sintering reaction: the powdery intermediate product of step (2) is mixed with Ar-H at a volume ratio of 93:7 2 In a mixed gas atmosphere, sintering at 650 °C for 4 h, the mixed ion phosphate cathode material Li 6 Na 3 V 3 (P 2 o 7 ) 3 (PO 4 ) 2 .

...

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Abstract

The invention belongs to the technical field of lithium ion battery positive electrode materials and discloses a mixed ion phosphate positive electrode material and a preparation method thereof. The positive electrode material has the chemical formula of Li(9-x)NaxV3(P2O7)3(PO4)2, wherein x is more than 0 and less than 9. The preparation method comprises the following steps: mixing a lithium salt or lithium hydroxide, a sodium salt or sodium hydroxide, a vanadium salt or oxides of vanadium, phosphate or phosphorus pentoxide which are used as raw materials according to a molar ratio (9-x) to x to (2.8-3.2) to 8 of lithium to sodium to vanadium to phosphorus, grinding or performing ball milling, thereby obtaining a precursor mixture; performing heat treatment on the precursor mixture for 2-10 hours at the temperature of 200-450 DEG C in air in a reducing atmosphere or an inert atmosphere; and finally, sintering for 4-72 hours at the temperature of 500-800 DEG C in a reducing atmosphere or an inert atmosphere, thereby obtaining the product. The positive electrode material disclosed by the invention comprises two conduction ions and has high charge and discharge voltage and specific discharge capacity.

Description

technical field [0001] The invention belongs to the technical field of positive electrode materials for lithium ion batteries, and in particular relates to a mixed ion phosphate positive electrode material and a preparation method thereof. Background technique [0002] Compared with general nickel-cadmium batteries and nickel-hydrogen batteries, lithium-ion batteries have the characteristics of higher working voltage. The average output voltage of commercial lithium-ion batteries with lithium cobalt oxide as the positive electrode material on the market is as high as 3.7V, so whether it is Mass energy density or volume energy density, lithium-ion batteries are currently the highest among various commercial secondary batteries. In addition, lithium-ion batteries also have the advantages of small size, light weight, long cycle life, fast charge and discharge, low self-discharge rate, and no memory effect. Since the first commercial lithium-ion battery came out in 1991, it has ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62
CPCC01B25/45H01M4/36H01M4/5825H01M4/62Y02E60/10
Inventor 邝泉赵彦明董有忠
Owner SOUTH CHINA UNIV OF TECH
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