Method for synthesizing Cl-doped LFP / C electrode material
By using acid-washed red iron oxide as raw material to prepare Cl-doped LFP/C electrode material, the problem of low conductivity of LiFePO4 electrode material was solved, battery performance was improved and cost was reduced, while the reuse of wastewater resources was achieved.
Patent Information
- Application Number
- CN202510808814.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-09-19
AI Technical Summary
The existing LiFePO4 electrode materials have low electronic and ionic conductivity, which limits their practical application. In addition, traditional doping methods rely on expensive precursors and do not fully utilize the pickling iron oxide red resources in pickling wastewater.
Acid-washed red iron oxide was used as raw material, and Cl-doped LFP/C electrode material was prepared by Cl doping and carbon coating. A low-cost solid-phase reaction method was used to combine lithium source, phosphorus source, carbon source and chlorine doping source, and then ball milling, drying, low-temperature calcination and high-temperature sintering were used to form high-performance electrode materials.
It significantly improves the rate and cycle performance of lithium-ion batteries, reduces production costs, and realizes the resource recycling of pickling red iron oxide, protecting the environment.
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Figure CN120664512A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of lithium-ion batteries, and in particular to a method for synthesizing a Cl-doped LiFePO4 / C electrode material. The prepared Cl-doped LiFePO4 / C electrode material can significantly improve the rate and cycle performance of lithium-ion batteries. Background Art
[0002] Olivine-type LiFePO4 materials have attracted widespread attention as cathode materials for rechargeable lithium-ion batteries (LIBs) due to their low toxicity, low cost and good safety performance. However, the low electronic and ionic conductivity of LFP electrode materials hinders their practical application. In recent years, people have improved the ionic and electronic conductivity of LFP electrodes by methods such as ion doping, carbon coating, and particle size reduction. Among them, carbon and its derivatives are currently the most widely used LFP surface modification materials, with the advantages of good stability, high conductivity and low cost. In addition, ion doping is also an important method to improve the electrochemical properties of LFP electrode materials. At present, there are many studies on the doping of metal ions Fe or Li, and the effect of anion doping on the electrochemical properties of LFP is relatively small.
[0003] At present, high-performance LFP electrode materials are obtained through a variety of synthesis methods, but these methods all rely on expensive precursors. In recent years, many studies have focused on the preparation of LFP electrode materials using low-cost raw materials. Some waste slags are also used as raw materials for obtaining LFP electrodes. With the development of the steel industry, China will produce 1 million cubic meters of pickling wastewater every year. Pickling wastewater is highly corrosive and will cause serious pollution to the environment. The recycling of pickling wastewater not only protects the environment, but also effectively realizes the reuse of resources and reduces resource waste. Pickling red iron oxide is a product of the pickling waste liquid recovery process, and its recovery method is relatively mature. However, there is still a lack of sufficient attention to the comprehensive utilization of pickling red iron oxide. Summary of the Invention
[0004] The purpose of the present invention is to provide a method for synthesizing Cl-doped LFP / C electrode material.
[0005] The method for synthesizing Cl-doped LFP / C electrode material provided by the present invention comprises the following steps:
[0006] 1) mixing a lithium source, a phosphorus source, and pickled red iron oxide in a solvent, ball-milling, and adding a carbon source material and a chlorine doping source to obtain a slurry;
[0007] 2) drying the obtained slurry to obtain a mixed powder material;
[0008] 3) The obtained mixed powder material is calcined at low temperature and sintered at high temperature to obtain Cl-doped LFP / C electrode material.
[0009] The invention uses pickled red iron oxide as a raw material to prepare Cl-doped LFP / C electrode material, which not only saves the production cost of the LFP electrode material but also provides a new idea for the comprehensive utilization of pickled red iron oxide.
[0010] In step 1) of the above method, the lithium source may be at least one of lithium carbonate, lithium hydroxide, lithium acetate, and lithium oxalate;
[0011] The phosphorus source may specifically be phosphate, more specifically NH4H2PO4;
[0012] The carbon source material can specifically be citric acid;
[0013] The chlorine doping source can specifically be ammonium chloride;
[0014] The molar ratio of the lithium source (calculated as Li), the phosphorus source (calculated as phosphorus), the pickled iron oxide red (calculated as iron) and the ammonium chloride is 1.03-1.2:1:1:0.03 respectively;
[0015] Based on the total mass of the lithium source, the phosphorus source and the pickled red iron oxide, the amount of the carbon source material added is 0.5%-5%;
[0016] The solvent may specifically be ethanol;
[0017] The ball milling time may be 1-10 hours, specifically 4 hours;
[0018] In step 2), the slurry is dried at 80-120° C. for 2-5 h, specifically at 60° C. for 12 h;
[0019] In step 3), the low-temperature calcination conditions are: calcination at 280-350°C for 2-4 hours, specifically calcination at 300°C for 3 hours; the high-temperature sintering conditions are: calcination at 700-800°C for 5-10 hours, specifically calcination at 750°C for 8 hours;
[0020] The operations of steps 1) to 3) are carried out in an inert atmosphere, specifically a nitrogen atmosphere.
[0021] The Cl-doped LFP / C electrode material prepared by the above method and the application of the electrode material in lithium-ion batteries also fall within the protection scope of the present invention.
[0022] The Cl-doped LFP / C electrode material is used as a positive electrode material for lithium-ion batteries.
[0023] The present invention also provides a lithium-ion battery, which uses the Cl-doped LFP / C electrode material as a positive electrode material.
[0024] This invention provides a method for preparing a high-performance electrode material—Cl-doped LiFePO4 / C cathode material. Using acid-washed red iron oxide as the raw material, this method significantly reduces costs. By employing a simple, low-cost solid-phase reaction, Cl-doping significantly improves electrical performance. The resulting Cl-doped LFP / C electrode material exhibits excellent rate and cycling performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 Comparison of the rate performance of LFP / C and Cl-doped LFP / C.
[0026] Figure 2 Comparison of the cycling performance of Cl-doped LFP / C and LFP / C at 0.1C and 10C rates. DETAILED DESCRIPTION
[0027] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.
[0028] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.
[0029] Example 1: Low-cost synthesis of Cl-doped LiFePO4 / C electrode material
[0030] Li2CO3, NH4H2PO4, NH4Cl, and acid-washed red iron oxide were weighed in a molar ratio (based on Li, P, NH4Cl, and Fe) of 1.05:1:0.03:1. The Li2CO3, NH4H2PO4, and acid-washed red iron oxide were magnetically stirred in ethanol and ball-milled for 4 hours. Citric acid (1% by weight) was added as a carbon source, neutralizing the NH4Cl as a dopant. The slurry was dried at 60°C for 12 hours to obtain a mixed powder. The mixture was then calcined at 300°C for 3 hours and finally sintered (at 750°C for 8 hours) to obtain the product.
[0031] Example 2, performance test
[0032] The Cl-doped LFP / C cathode material prepared in Example 1 was mixed with PVDF, KS6, and Super-Li (mass ratio 8:1:0.5:0.5), and NMP was added to prepare an electrode slurry. The electrode slurry was coated on aluminum foil to prepare the electrodes used. According to the battery process, a soft pack battery was assembled. The electrolyte used was 1 mol L -1LiPF6 was mixed with diethyl carbonate (DEC), ethylene carbonate (EC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1;
[0033] Undoped LFP / C cathode material was mixed with PVDF, KS6, and Super-Li (mass ratio 8:1:0.5:0.5), and NMP was added to prepare electrode slurry. The electrode slurry was coated on aluminum foil to prepare the electrodes used. According to the battery process, the soft pack battery was assembled. The electrolyte used was 1 mol L -1 LiPF6 was mixed with diethyl carbonate (DEC), ethylene carbonate (EC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1;
[0034] The rate performance of the two batteries was investigated, and the results were as follows: Figure 1 shown.
[0035] Figure 1 The Cl-doped LFP / C electrode exhibited a relatively excellent reversible capacity of 124.1 mAh g at 2C. -1 , reaching 97mAh g at 10C -1 In contrast, the reversible capacity of the undoped LFP / C electrode at 2C is only 103.5 mAh g -1 , drops to 75mAh g at 10C -1 .
[0036] The cycle performance of the two batteries was investigated.
[0037] Figure 2 Comparison of the cycling performance of Cl-doped LFP / C and LFP / C at 0.1C and 10C rates.
[0038] From the cycling performance of Cl-doped LFP / C and undoped LFP / C electrodes at 0.1C (first 100 cycles) and 10C (last 500 cycles), it can be observed that the discharge capacity of the Cl-doped LFP / C electrode is the largest at 105.3 mAh g -1 , and maintained 96.4 mAh g at 10C after 500 cycles -1 However, the discharge capacity of the undoped LFP / C electrode was a maximum of 111.3 mAh g -1 , but only maintained 69.8 mAh g after 500 cycles at 10C. -1 It is noteworthy that in the initial stage of cycling, the discharge specific capacity of both Cl-doped LFP / C and undoped LFP / C electrodes at 0.1C increases with the number of cycles, which can be attributed to the activation process of the LFP / C electrode material during the charge and discharge processes.
[0039] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that further improvements can be made to the present invention. In short, according to the principles of the present invention, this application is intended to include any changes, uses or improvements to the present invention, including changes that depart from the disclosed scope in this application and are made using conventional techniques known in the art.
Claims
1. A method for synthesizing Cl-doped LFP / C electrode material, comprising the following steps: 1) mixing a lithium source, a phosphorus source, and pickled red iron oxide in a solvent, ball-milling, and adding a carbon source material and a chlorine doping source to obtain a slurry; 2) drying the obtained slurry to obtain a mixed powder material; 3) The obtained mixed powder material is calcined at low temperature and sintered at high temperature to obtain Cl-doped LFP / C electrode material.
2. The method for synthesizing Cl-doped LFP / C electrode material according to claim 1, characterized in that: In step 1), the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium acetate, and lithium oxalate; The phosphorus source is phosphate, specifically NH4H2PO4.
3. The method for synthesizing Cl-doped LFP / C electrode material according to claim 1, characterized in that: In step 1), the carbon source material is citric acid; and the chlorine doping source is ammonium chloride.
4. The method for synthesizing Cl-doped LFP / C electrode material according to claim 2 or 3, characterized in that: The molar ratio of the lithium source (calculated as Li), the phosphorus source (calculated as phosphorus), the pickled iron oxide red (calculated as iron) and the ammonium chloride is 1.03-1.2:1:1:0.03, respectively; Based on the total mass of the lithium source, the phosphorus source and the pickled red iron oxide, the added amount of the carbon source material is 0.5%-5%.
5. The method for synthesizing Cl-doped LFP / C electrode material according to claim 1, characterized in that: The solvent is ethanol; The ball milling time is 1-10 hours.
6. The method for synthesizing Cl-doped LFP / C electrode material according to claim 1, characterized in that: In step 2), the slurry is dried at 80-120° C. for 2-5 hours.
7. The method for synthesizing Cl-doped LFP / C electrode material according to claim 1, characterized in that: In step 3), the low-temperature calcination conditions are: calcination at 280-350° C. for 2-4 hours; the high-temperature sintering conditions are: calcination at 700-800° C. for 5-10 hours.
8. A Cl-doped LFP / C electrode material prepared by the method for synthesizing a Cl-doped LFP / C electrode material according to any one of claims 1 to 7.
9. Use of the Cl-doped LFP / C electrode material according to claim 8 in a lithium-ion battery.
10. A lithium-ion battery, comprising the Cl-doped LFP / C electrode material according to claim 8 as a positive electrode material.