Method for preparing lithium iron phosphate-lithium vanadium phosphate by quenching method

A technology of lithium iron phosphate and lithium vanadium phosphate, applied in electrical components, battery electrodes, circuits, etc., can solve the problems of unsatisfactory high-rate charge and discharge performance, poor low-temperature performance and rate performance, and unsatisfactory charge and discharge effect. Good high-rate charge-discharge performance, improved rate performance, and improved electronic conductivity

Inactive Publication Date: 2012-02-22
CENT SOUTH UNIV +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] LiFePO 4 and Li 3 V 2 (PO 4 ) 3 are two representative phosphate system cathode materials, but LiFePO 4 The conductivity of Li 3 V 2 (PO 4 ) 3 It has a high theoretical specific capacity (197 mAh·g -1 ), high working potential (3.6-4.5V vs. Li/Li + ), stable structure, good electrochemical performance, etc., but the metal ions in the crystal structure are far apart, which reduces the mobility of electrons in the material, resulting in low electronic conductivity of the material, and the charging and discharging effect under high current is not good. Ideally, the two traditional phosphate cathode materials LiFePO 4 and Li 3 V 2 (PO 4 ) 3 Copy

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  • Method for preparing lithium iron phosphate-lithium vanadium phosphate by quenching method
  • Method for preparing lithium iron phosphate-lithium vanadium phosphate by quenching method
  • Method for preparing lithium iron phosphate-lithium vanadium phosphate by quenching method

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Example Embodiment

[0017] Example 1:

[0018] Using vanadium pentoxide, iron phosphate, lithium carbonate, and ammonium dihydrogen phosphate as raw materials, according to composite materials x LiFePO 4 · y Li 3 V 2 (PO 4 ) 3 The stoichiometric ratio of x : y =5:1 Mix evenly, add a certain amount of citric acid, stir and disperse evenly in water, then spray dry, then put it into a tube furnace, keep the temperature at 600°C for 18 hours under an argon atmosphere, and then put the high temperature The charge was quickly quenched in water at 25°C, liquid nitrogen at -193°C, and dry ice at -78°C for 0.5 hours, and the obtained material was analyzed by X-ray diffraction to be monoclinic and olivine. x LiFePO 4 · y Li 3 V 2 (PO 4 ) 3 composite structure. The product obtained by SEM is spherical, and the tap density is shown in Table 1. The resulting products were assembled into button batteries and charged and discharged at a rate of 10C. Their first discharge capacity is shown in Tab...

Example Embodiment

[0021] Example 2:

[0022] Using vanadium dioxide, ferrous acetate, lithium formate, and triammonium phosphate as raw materials, according to composite materials x LiFePO 4 · y Li 3 V 2 (PO 4 ) 3 The stoichiometric ratio of x : y =10:1 mix evenly; add a certain amount of oxalic acid, stir and disperse evenly in ethanol, then spray dry, and then put it into a tube furnace, under a hydrogen atmosphere, keep the temperature at 700°C for 2 hours, and then put the high-temperature furnace charge Quickly placed in water at 0°C, 20°C, and 35°C for 1 hour, the obtained material was analyzed by X-ray diffraction as monoclinic crystal and olivine crystal, namely x LiFePO 4 · y Li 3 V 2 (PO 4 ) 3 composite structure. The product obtained by SEM is spherical, and the tap density is shown in Table 2. The resulting products were assembled into button batteries to charge and discharge at a rate of 10C, and their first discharge specific capacities are shown in Table 2

[002...

Example Embodiment

[0025] Example 3:

[0026] Using ammonium metavanadate, ferrous oxalate, lithium oxide, diammonium hydrogen phosphate as raw materials, according to composite materials x LiFePO 4 · y Li 3 V 2 (PO 4 ) 3 The stoichiometric ratio of x : y =1:10 mixed evenly; add a certain amount of sucrose, stir and disperse evenly in acetone, then spray dry, and then put it into a tube furnace, under a nitrogen atmosphere, keep the temperature at 800°C for 15 hours, Quickly placed in dry ice at -78.5°C for 5 minutes, the obtained material was analyzed by X-ray diffraction as monoclinic and olivine, namely x LiFePO 4 · y Li 3 V 2 (PO 4 ) 3 composite structure. The spherical shape of the product can be obtained by SEM, and the tap density is as high as 1.50 g cm -3 . The obtained product was assembled into a button battery and charged and discharged at a rate of 10C, and the specific capacity of the first discharge was 138mAh·g -1 .

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Abstract

A method for preparing lithium iron phosphate-lithium vanadium phosphate by a quenching method. The method comprises the following steps: well mixing a vanadium source compound, an iron source compound, a lithium source compound and a phosphor source compound according to a stoichiometric ratio of the composite material, adding a carbon source, stirring and mixing, uniformly distributing the mixture in a solvent, performing spray drying to prepare a spherical precursor mixture, calcining the precursor mixture at 500-900 DEG C in nonoxidative atmosphere for 2-48 hours, finally transferring the high-temperature powder to a low-temperature medium with a temperature of -209 DEG C-35 DEG C, quenching for 1 min-2 h so as to prepare the lithium iron phosphate-lithium vanadium phosphate composite material. The invention can prepare a composite cathode material with a high tap density and high magnification performance, and greatly improves the energy density and magnification performance of the material.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate-lithium vanadium phosphate, a composite positive electrode material for a lithium ion battery, in particular to the preparation of a composite positive electrode material by a spray drying-quenching method x LiFePO 4 · y Li 3 V 2 (PO 4 ) 3 Methods. Background technique [0002] LiFePO 4 and Li 3 V 2 (PO 4 ) 3 are two representative phosphate system cathode materials, but LiFePO 4 The conductivity of Li 3 V 2 (PO 4 ) 3 It has a high theoretical specific capacity (197 mAh·g -1 ), high working potential (3.6-4.5V vs. Li / Li + ), stable structure, good electrochemical performance, etc., but the metal ions in the crystal structure are far apart, which reduces the mobility of electrons in the material, resulting in low electronic conductivity of the material, and the charging and discharging effect under high current is not good. Ideally, the two traditional phosphate ca...

Claims

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Application Information

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IPC IPC(8): H01M4/58
CPCY02E60/10
Inventor 郑俊超张宝张佳峰
Owner CENT SOUTH UNIV
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