Preparation method of sodium vanadium trifluorophosphate serving as positive electrode material of sodium-ion battery

A technology of sodium vanadium trifluorophosphate and sodium ion batteries, which is applied in the direction of battery electrodes, positive electrodes, secondary batteries, etc., can solve the problems of battery operating voltage and energy density reduction, cycle stability deterioration, etc., to improve the average working Effects of voltage and energy density, energy density value increase, and easy availability of raw materials

Pending Publication Date: 2020-09-01
HARBIN INST OF TECH
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  • Claims
  • Application Information

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Problems solved by technology

[0005] In order to solve the problems of heterogeneous sodium vanadium phosphate generated due to the volatilization of fluorine element in the preparation process of sodium vanadium trifluorophosphate, the positive electrode material of sodium ion battery, which leads to the reduction of battery operating voltage and energy den

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  • Preparation method of sodium vanadium trifluorophosphate serving as positive electrode material of sodium-ion battery

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[0030] Specific embodiment one: This embodiment describes a method for preparing sodium-ion battery cathode material sodium vanadium trifluorophosphate, the constant current charge and discharge curve of the obtained cathode material does not appear in the 3.3V brought by the miscellaneous phase (vs. Na + / Na) about the discharge voltage platform, the method includes the following steps:

[0031] Step 1: Dissolve the carbon source in deionized water at room temperature, stir and mix evenly to obtain a clear solution M 1 , Adjust M 1 The pH is weakly acidic; in this step, the total molar amount of the added carbon source is affected by the solution M 1 There is a limitation on the maximum dissolution of raw materials. During the operation, the added carbon source and other raw materials (vanadium source, phosphorus source, sodium source and fluorine source) must be completely dissolved in the solution;

[0032] Step 2: Weigh the vanadium source with a molar ratio of 5:2 to the total ...

Example Embodiment

[0037] Specific embodiment two: a method for preparing sodium-ion battery cathode material sodium vanadium trifluorophosphate according to specific embodiment one, in step one, the carbon source is an organic acid and / or ammonium salt, and the organic acid is Citric acid monohydrate and / or anhydrous citric acid; the ammonium salt is a mixture of one or more of ammonium dihydrogen citrate, diammonium hydrogen citrate, and triammonium citrate. When the first and second types of carbon sources are selected at the same time, the acid and the acid ammonium salt can form a pH conjugate acid-base pair with buffering effect in the solution.

Example Embodiment

[0038] Specific embodiment three: The method for preparing sodium-ion battery cathode material sodium vanadium trifluorophosphate described in specific embodiment one or two, in step one, the weak acidity refers to a pH of 3.0-5.0. The purpose is to speed up the complexation reaction in step two on the one hand, and on the other hand to inhibit the hydrolysis of fluorine and reduce its volatilization.

[0039] Specific embodiment four: A method for preparing sodium vanadium trifluorophosphate, a cathode material for sodium ion batteries described in specific embodiment three, includes two ways to adjust the solution to be weakly acidic: one is to drop ammonia directly into the solution; Under the premise that the total amount of carbon source to be added has been selected in step 1, organic acid carbon source and ammonium salt carbon source are selected at the same time, and this is achieved by adjusting the ratio and corresponding amount of the two types of carbon sources.

[0040...

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Abstract

The invention discloses a preparation method of sodium vanadium trifluorophosphate serving as a positive electrode material of a sodium-ion battery and belongs to the technical field of battery material synthesis. The preparation method comprises the following steps: (1) dissolving raw materials such as a carbon source, a vanadium source, a phosphorus source, a fluorine source and a sodium source;(2) removing free water under a heating condition to obtain wet sol; (3) carrying out vacuum drying on the wet sol to obtain dry gel; (4) grinding the dry gel to obtain a powdery precursor; and (5) under the protection of a flowing inert atmosphere, presintering and roasting the precursor, and cooling along with the furnace. The sodium vanadium trifluorophosphate serving as a positive electrode material of a sodium-ion battery prepared by the method is high in purity, a low working voltage platform of about 3.3V (vs.Na<+>/Na) caused by a miscellaneous phase is eliminated, and the working voltage and the energy density of the positive electrode material are improved. The preparation method is simple to operate and good in reproducibility, and the prepared material has relatively high energy density and excellent rate and cycle performances and can meet the requirements of practical application of the sodium ion battery.

Description

technical field [0001] The invention belongs to the technical field of battery material synthesis, and in particular relates to a preparation method of sodium vanadium trifluorophosphate, a positive electrode material of a sodium ion battery. Background technique [0002] Lithium-ion batteries have become an ideal power source for portable electronic devices such as mobile phones, laptop computers, and high-quality cameras due to their high operating voltage, high energy density, and low environmental pollution. With the rise of the electric vehicle industry, the market's demand for lithium resources, which lithium-ion batteries rely on, has increased sharply, and its price has continued to rise. However, lithium reserves are limited after all. In the near future, lithium resources will be depleted and prices will skyrocket. Therefore, it is imminent to develop high-efficiency energy storage materials and devices with abundant resources, low price, high safety and long serv...

Claims

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Application Information

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IPC IPC(8): C01B25/455C01B25/45H01M4/58H01M10/054
CPCC01B25/455C01B25/45H01M4/5825H01M4/582H01M10/054C01P2002/72C01P2006/40H01M2004/021H01M2004/028Y02E60/10
Inventor 王振波邓亮阙兰芳隋旭磊玉富达赵磊
Owner HARBIN INST OF TECH
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