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A kind of composite cathode material and its preparation method and application

A composite cathode material, composite carbon technology, applied in nanotechnology, battery electrodes, nanotechnology and other directions for materials and surface science, can solve the problems of only about 3.2V, low working voltage, etc., to solve the problem of low working voltage Effect

Active Publication Date: 2020-02-21
LANGFANG GREEN IND TECH CENT +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Among the phosphate series lithium-ion battery cathode materials, lithium iron phosphate material has achieved great success in the field of electric vehicles due to its excellent safety performance and cycle performance, but the working voltage of lithium iron phosphate material is low, and the voltage platform is only About 3.2V, the theoretical capacity is 167mAh / g, and the actual capacity is only about 140mAh / g. Therefore, lithium-ion batteries using lithium iron phosphate materials are only suitable for applications that do not require high energy density and high safety requirements. For example, electric buses, electric vehicles, and distributed energy storage

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0083] (1) Preparation of lithium manganese iron phosphate cathode material as the core

[0084] Lithium carbonate, iron phosphate, manganese carbonate, lithium dihydrogen phosphate, nitrogen-doped metatitanic acid, sulfur-doped graphene and deionized water were weighed in proportion, and high-energy ball milled at 200 rpm for 2 hours to obtain a mixed Uniform slurry. Wherein, the molar ratio of lithium, manganese, iron and metatitanic acid is 1.05:0.45:0.55:0.03, and the content of sulfur-doped graphene is 10% of the total mass of the lithium manganese iron phosphate cathode material. The above slurry was dried by microwave and then calcined at 750°C for 8 hours, crushed and refined to obtain lithium manganese iron phosphate core with good crystallinity and conductivity and high specific capacity.

[0085] (2) Prepare a lithium vanadium phosphate shell on the surface of the inner core to prepare a composite positive electrode material

[0086] The lithium manganese iron pho...

Embodiment 2

[0089] (1) Preparation of lithium manganese iron phosphate cathode material as the core

[0090] Lithium chloride, ferrous oxalate, manganese oxalate, lithium sulfate, nitrogen-doped nano-titanium dioxide, sulfur-doped graphene and deionized water are weighed in proportion, and high-energy ball milling at 800 rpm for 5 hours to obtain a uniform mixture of slurry. Among them, the molar ratio of lithium, manganese, iron and nano-titanium dioxide is 1.00:0.25:0.70:0.05, and the content of sulfur-doped graphene is 3% of the total mass of the lithium iron manganese phosphate cathode material. The above slurry was dried by microwave and then calcined at 900°C for 12 hours, crushed and refined to obtain lithium manganese iron phosphate core with good crystallinity and conductivity and high specific capacity.

[0091] (2) Prepare a lithium vanadium phosphate shell on the surface of the inner core to prepare a composite positive electrode material

[0092] The lithium manganese iron ...

Embodiment 3

[0095] (1) Preparation of lithium manganese iron phosphate cathode material as the core

[0096] Lithium bicarbonate, ferrous nitrate, manganese hydroxide, lithium hydroxide, nitrogen-doped metatitanic acid, sulfur-doped graphene, and deionized water were weighed in proportion, and high-energy ball milled at a speed of 350 rpm for 10 h. A homogeneous slurry is obtained. Among them, the molar ratio of lithium, manganese, iron and metatitanic acid is 0.98:0.30:0.88:0.008, and the content of sulfur-doped graphene is 7.5% of the total mass of the lithium iron manganese phosphate cathode material. The above slurry was dried by microwave and then calcined at 1000°C for 4 hours, crushed and refined to obtain lithium manganese iron phosphate core with good crystallinity and conductivity and high specific capacity.

[0097] (2) Prepare a lithium vanadium phosphate shell on the surface of the inner core to prepare a composite positive electrode material

[0098] The lithium manganese ...

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Abstract

The invention discloses a composite positive electrode material and a preparation method and an application thereof, and belongs to the technical field of preparation of an electrochemical power supply material. The composite positive electrode material provided by the invention adopts a core-shell structure, wherein the inner core is metal oxide-doped and composite carbon material-coated lithiummanganese iron phosphate, and the shell is metal oxide-doped and composite carbon material-coated lithium vanadium iron phosphate. The composite positive electrode material provided by the invention has excellent cycle life, high-rate discharging and low-temperature performance and safety performance, as well as relatively high energy density. When the composite positive electrode material is at 0.5C rate, the initial discharging specific capacity of a button cell is greater than 155mAh / g, and after 100 cycles, the capacity retention ratio is greater than 95%.

Description

technical field [0001] The invention relates to a composite positive electrode material and its preparation method and application, belonging to the technical field of preparation of electrochemical power source materials, in particular to the technical field of preparation of lithium ion secondary battery positive electrode materials. Background technique [0002] Lithium-ion batteries have outstanding advantages such as large discharge specific capacity, high voltage platform, safety, long life, and environmental friendliness. At present, they are widely used in various fields such as small portable batteries, power batteries for new energy vehicles, and energy storage. The cathode material, which accounts for about 35% of the cost of lithium-ion batteries, is the core technology for the replacement of lithium-ion batteries and the key to the promotion of new energy vehicles. In-depth research on cathode materials for lithium-ion batteries has important practical significan...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/485H01M4/525H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/485H01M4/525H01M4/5825H01M4/62H01M4/625H01M10/0525Y02E60/10
Inventor 谭强强徐宇兴
Owner LANGFANG GREEN IND TECH CENT
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