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Composite coated modified high vibrancy solid lithium ionic battery positive electrode, preparation and application thereof

A lithium-ion battery, tap density technology, applied in electrode manufacturing, battery electrodes, chemical instruments and methods, etc., can solve the problems of complex process, reduction of material volume specific energy and volume specific power, limited improvement of electrochemical performance, etc. , to achieve high volume specific energy and volume specific power, simplify the composite coating modification process, and facilitate industrialized large-scale production.

Inactive Publication Date: 2009-01-07
SOUTH CHINA UNIV OF TECH
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Problems solved by technology

[0004] 1. Although the mechanical alloy method, solution spray technology and other synthesis methods can synthesize LiFePO with a smaller particle size 4 / C material shortens the de / intercalation path of lithium ions and improves the conductivity of the material, but the method of simply coating carbon requires more carbon, because the density of carbon is higher than that of LiFePO 4 The smaller particle size will significantly reduce the tap density of the material; and the smaller particle size increases the contact area between the material particles, which will also reduce the tap density of the material, thereby reducing the volume specific energy and Volume Specific Power
In addition, the above method also has disadvantages such as high requirements on equipment or complicated process, and it is not easy to carry out large-scale industrial production.
[0005] 2. The method of composite coating of carbon and Ag can reduce the coating amount of carbon and has little influence on the tap density of the material, but it is difficult to control the uniform distribution of the coating material, and it also involves a variety of experimental methods , the process is more complicated, and the actual operation is difficult
[0006] 3. LiM generated by doping metal elements (expressed as M) heteroatoms such as manganese or cobalt y Fe 1-y PO 4 , although it can improve the bulk electronic conductivity of the material, it does not help to reduce the grain size of the material, and cannot improve the lithium ion diffusion rate of the material, so it has a limited effect on improving the electrochemical performance of the material
[0007] 4. Two liquid-phase synthesis methods, liquid-phase co-precipitation and controlled crystallization, were used to prepare spherical particles to improve LiFePO 4 When the tap density is high, it is necessary to strictly control the temperature, pH value, ion concentration, stirring intensity and co-precipitation or crystallization speed of the reaction system, etc., and there are problems of complicated operation steps and difficult industrialization
[0008] 5. Fe 2 o 3 or FePO 4 When the ferric compound is used as the iron source to synthesize lithium iron phosphate, there is also the problem of a large amount of coated carbon, which will significantly reduce the tap density of the material.

Method used

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  • Composite coated modified high vibrancy solid lithium ionic battery positive electrode, preparation and application thereof
  • Composite coated modified high vibrancy solid lithium ionic battery positive electrode, preparation and application thereof
  • Composite coated modified high vibrancy solid lithium ionic battery positive electrode, preparation and application thereof

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Embodiment 1

[0037] The first step is to prepare 0.05mol LiFePO 4 , first weigh 0.025mol of Li 2 CO 3 and 0.05mol of (NH 4 ) 2 HPO 4 After that, add 20% 0.05mol LiFePO 4 Heavy organic iron source - ferric citrate (1.9097g). At this time, the content of iron has not reached the amount required by stoichiometry, and the insufficient amount of iron is obtained from the source of inorganic iron——Fe 2 o 3 Come to make up (3.5371g), take 28.5g ethanol as dispersant, mix through high-speed ball milling;

[0038] In the second step, put the mixed raw materials in a 30ml alumina crucible, put them into a well-type furnace, pass in nitrogen gas for protection, heat at 300°C for 10 hours, cool and grind to obtain PO 4 3- , Li + , Fe 2+ / Fe 3+ and the reactive precursor of conductive carbon;

[0039] The third step is to put the reaction precursor into a 30ml alumina crucible, place it in a well-type furnace, pass through nitrogen as a protection, calcinate at 700°C for 24h, and obtain Li...

Embodiment 2

[0044] The first step is to prepare 0.05mol LiFePO 4 , first weigh 0.05mol of lithium acetate and 0.05mol of NH 4 h 2 PO 4 After that, add 10% 0.05mol LiFePO 4 Heavy source of organic iron - ferric citrate (0.9481 g). At this time, the amount of iron has not reached the stoichiometric amount, and the insufficient amount of iron is replaced by inorganic iron source——Fe 3 o 4 (3.6404g) to make up, take 40g ethanol as dispersant, mix through high-speed ball milling;

[0045] In the second step, put the mixed raw materials in a 30ml alumina crucible and put them into a well-type furnace, pass in nitrogen gas for protection, heat at 250°C for 5 hours, cool and grind to obtain PO 4 3- , Li + , Fe 2+ / Fe 3+ and the reactive precursor of conductive carbon;

[0046] The third step is to put the reaction precursor into a 30ml alumina crucible, place it in a well-type furnace, pass through nitrogen as a protection, calcinate at 800°C for 5h, and obtain LiFePO after cooling wi...

Embodiment 3

[0049] The first step is to prepare 0.05mol LiFePO 4 , first weigh 0.05mol of LiNO 3 After that, add 45% 0.05molLiFePO 4 Heavy organic iron source - ferric citrate (4.2685g), at this time the amount of iron has not reached the stoichiometric, insufficient iron source - FePO 4 (5.6195g) to make up. However, at this time the PO in the precursor 4 3- The amount has not reached the stoichiometric amount, and the insufficient amount of phosphate radical is (NH 4 ) 3 PO 4 (1.9000g) is insufficient, with 14g ethanol as dispersant, mix through high-speed ball mill;

[0050] In the second step, put the mixed raw materials in a 30ml alumina crucible, put them into a well-type furnace, pass in nitrogen gas for protection, heat at 450°C for 20 hours, cool and grind to obtain PO 4 3- , Li + , Fe 2+ / Fe 3+ and the reactive precursor of conductive carbon;

[0051] The third step is to put the reaction precursor into the reactor, place it in a well-type furnace, pass through nitr...

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Abstract

The invention provides a lithium-ion battery anode material with compound cladding modification and high tap density and a preparation method thereof and an application thereof to the manufacturing field of lithium-ion batteries. The material of the invention consists of carbon, Fe2P and lithium iron phosphate. The carbon and the Fe2P form a conductive nanometer network to compound and clad the lithium iron phosphate particles so as to form the LiFePO4 / (C+Fe2P) compound material. The lithium-ion battery anode material of the invention takes the mixture of an organic ferric iron compound and an inorganic ferric iron compound as an iron source, and is mixed with the compound of the lithium source and the phosphorous source, and makes use of a solid phase-carbon thermal reduction method to prepare the material. The preparation method of the invention is relatively simple and practicable, the price of the raw material is relatively cheap, the production cost is relatively low, and the prepared material has good electrochemical performance, high tap density and is suitable for industrialized production.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and specifically refers to a high-tap-density composite-coated modified lithium-ion battery positive electrode material and a preparation method and application thereof. Background technique [0002] Olivine lithium iron phosphate (LiFePO 4 ) has the advantages of rich material sources, good safety, high theoretical specific capacity, long cycle life, and environmental friendliness, especially its thermal stability and high-temperature cycle performance are particularly good, and it is considered to be the most practical lithium ion One of the positive electrode materials for power batteries. [0003] However, lithium iron phosphate also has some significant disadvantages. One is that the migration rate and electron conductivity of lithium ions are low, which affects the high-rate performance of the resulting battery; the other is that its theoretical tap density is small (3.6g / cm...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/04C01B25/45B01J19/00B22F1/02H01M4/62
CPCY02E60/10
Inventor 周震涛钟美娥
Owner SOUTH CHINA UNIV OF TECH
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