Phosphorus source and phosphorus slag modified hard carbon negative electrode material and preparation process

Abstract

The application discloses a phosphorus source and phosphorus slag modified hard carbon negative material and a preparation process, and belongs to the technical field of battery negative materials. Two types of preparation schemes which can be independently implemented are arranged, and the hard carbon negative material is prepared by taking industrial yellow phosphorus and yellow phosphorus smelting glass body phosphorus slag as core modified components and collocating three-element composite carbon sources of anthracite, coke and machine-made carbon. In scheme one, high proportion of phosphorus is in-situ doped by industrial yellow phosphorus; in scheme two, the phosphorus slag is subjected to acid pickling and impurity removal to form a phosphorus-silicon composite modification system, and the structural stability is improved by using a mineral dense skeleton. The integrated dry process of crushing, mixing, sectional pre-oxidation and inert atmosphere high-temperature carbonization is adopted, and the problems of loose structure, easy pulverization in cycles and low capacity of conventional coal-based hard carbon are improved. The raw materials of the application have no regional limitation and are suitable for industrial production, the electrochemical performance of the obtained material is better than that of conventional coal-based hard carbon, and the application is suitable for lithium ion batteries, sodium ion batteries and energy storage fields.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage battery anode material technology, specifically involving a modified hard carbon anode material and its dry preparation process, which uses industrial yellow phosphorus and yellow phosphorus smelting glassy phosphorus slag as dual phosphorus sources, combined with anthracite, coke and machine-made carbon as ternary composite carbon sources. Background Technology

[0002] Existing commercial low-cost hard carbon anodes are mainly prepared from single coal, coke, and biochar as raw materials, which have technical shortcomings such as loose structure, large loss of high-temperature carbonization components, easy pulverization and collapse during cycle charging and discharging, and low capacity limit.

[0003] Currently, most phosphorus-modified hard carbon technologies in the industry use chemical reagents such as phosphoric acid, phosphates, and red phosphorus as trace phosphorus sources, with carbon sources being the absolute main component. No technical solutions have been found that use industrial yellow phosphorus or yellow phosphorus slag as high-proportion functional components, combined with ternary composite carbon sources.

[0004] Existing technologies for the resource utilization of yellow phosphorus slag are mainly used for cement fillers, roadbed materials, and the preparation of lithium iron phosphate cathodes. Among them, the lithium iron phosphate cathode technology uses iron-rich phosphorus slag, which relies on the combination of iron and phosphorus to generate crystalline cathode materials. This technology is completely different from the technical principle, process route, and product structure of the present invention, which uses low-iron glassy phosphorus slag to prepare negative electrode carbon materials. There is no technological overlap or conflict. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor structural stability, limited energy storage capacity, and low raw material utilization of traditional coal-based hard carbon, and to provide two independent and feasible preparation methods.

[0006] This invention uses a ternary compound of anthracite, coke, and machine-made charcoal as a composite carbon source: anthracite provides the basic carbon skeleton and energy storage carrier; coke improves the overall conductivity and mechanical strength of the material; and machine-made charcoal regulates the internal pore structure. The three components work together to optimize the overall performance. No natural wood is used in the entire charcoal production process, which meets environmental protection requirements.

[0007] Option 1 is a high-purity phosphorus modification route: increasing the proportion of industrial yellow phosphorus added, resulting in high phosphorus purity, which can fully widen the carbon interlayer spacing, increase electrochemical active sites, and improve storage capacity and fast charging performance.

[0008] Option 2 is a low-cost solid waste approach: increasing the proportion of yellow phosphorus smelting glassy slag, and after acid washing to remove impurities, using phosphorus element modification + silicon-calcium mineral framework support to solve the problem of traditional carbon material recycling collapse, resulting in high solid waste utilization and low production costs. Detailed Implementation

[0009] Example 1: Industrial Yellow Phosphorus Modification Scheme By total mass: industrial yellow phosphorus 30%, composite carbon source 70%; Internal proportions of composite carbon source: 50% anthracite, 30% coke, and 20% machine-made charcoal; All raw materials are crushed to 200-300 mesh and mixed evenly; pre-oxidized at 300℃ for 60 min; segmented carbonization under nitrogen atmosphere, held at 700℃ for 1 h, and held at 1100℃ for 2.5 h; after cooling, crushing and grading, the finished negative electrode material is obtained.

[0010] Example 2: Modification scheme for yellow phosphorus slag By total mass: pickled yellow phosphorus slag 35%, composite carbon source 65%; Internal proportions of composite carbon source: 50% anthracite, 30% coke, and 20% machine-made charcoal; After being washed with dilute hydrochloric acid to remove impurities and dried, the yellow phosphorus vitreous slag was mixed with the remaining raw materials; pre-oxidized at 280℃ for 70 min; carbonized in stages under nitrogen atmosphere, held at 650℃ for 1 h, and held at 1050℃ for 3 h; and then crushed and graded to obtain the finished product. Technical Comparative Analysis

[0011] Structural stability comparison Traditional single-element coal-based hard carbon has a single organic matrix, low density, high high-temperature volatilization loss, easy pulverization during cyclic charging and discharging, and weak structural stability.

[0012] This invention utilizes a ternary carbon source and a high proportion of phosphorus components: anthracite forms the basic framework, coke enhances strength, and machine-made char optimizes porosity; combined with the chemical bonding of phosphorus and the rigid support of mineral glass, the overall structure is not prone to collapse and its cycle stability is significantly improved.

[0013] Electrochemical performance comparison Traditional coal-based hard carbon: reversible capacity 260-300 mAh / g, initial coulombic efficiency 76-85%, capacity retention rate less than 80% after 500 cycles.

[0014] The modified hard carbon of this invention has a reversible capacity of 360-450 mAh / g, an initial coulombic efficiency of 88-91%, and a capacity retention rate of ≥85% after 500 cycles.

[0015] Comparison of raw material utilization rates Traditional coal-based carbonization has an effective retention rate of 60-75%; the system of this invention has an effective component retention rate of ≥90%, resulting in lower raw material loss.

[0016] The fundamental difference from existing phosphorus slag cathode technology Existing phosphorus slag cathode technology: Select iron- and phosphorus-rich slag, wet-process leaching of iron and phosphorus elements, synthesize crystalline cathode materials, and store electricity by relying on changes in metal valence state.

[0017] The negative electrode technology of this invention uses low-iron glassy phosphorus slag, dry solid-phase carbonization, and relies on carbon layer intercalation of ions and phosphorus-silicon structure modification for energy storage. The raw materials, processes, mechanisms and products are completely different, and there is no patent overlap or conflict. Attached Figure Description

[0018] The attached figures are schematic diagrams of the present invention. Figure 1 is a schematic diagram of the preparation process of the hard carbon anode material of the present invention; Figure 2 is a schematic diagram of the microstructure of the modified hard carbon anode material of the present invention.

[0019] Explanation of reference numerals in the attached figures 1: Composite carbon matrix; 2: Phosphorus-doped modified region; 3: Mineral glass support framework; 4: Ion transport channels. Detailed description of each sub-image Figure 1. Process flow diagram: This figure is a vertical layout of the preparation process flowchart. Each process is labeled in Chinese, showing the complete production process in sequence. It also serves as the abstract diagram and the main diagram in the instruction manual.

[0020] Figure 2. Schematic diagram of microstructure: This figure only shows the microstructure of the material of the present invention, and only Arabic numerals 1, 2, 3, and 4 are labeled in the figure. Label 1 represents the overall composite carbon matrix of the material; label 2 represents the phosphorus-doped modified regions distributed in the carbon matrix; label 3 represents the mineral glass support framework interspersed in the matrix; label 4 represents the interconnected ion transport channels inside the material. Functional features

[0021] Two independent preparation routes are adopted: the high-proportion yellow phosphorus route focuses on high performance, while the yellow phosphorus slag solid waste route focuses on low cost, adapting to different production needs.

[0022] It explicitly uses a ternary composite carbon source of anthracite, coke, and machine-made charcoal, with the three components having complementary properties. Natural charcoal is not used, making it compliant and environmentally friendly.

[0023] By limiting the proportion of phosphorus-based components, the effects of phosphorus doping and phosphorus-silicon co-doping are fully utilized to widen the carbon layer spacing and improve energy storage capacity and charge / discharge efficiency.

[0024] Yellow phosphorus slag has its own mineral skeleton, which improves the defects of pulverization and structural collapse in the recycling process of traditional carbon materials.

[0025] The dry segmented carbonization process is simple and suitable for large-scale production; the raw materials are not limited by region and the supply is stable.

[0026] This technology differs significantly from existing coal-based hard carbon, trace chemical phosphorus-doped hard carbon, and phosphorus slag-based cathode materials, and possesses novelty and inventiveness. Prior art distinction and inventive step description

[0027] A search of existing publicly available patents and related technical literature reveals several existing technical solutions in the industry. These include blends of coal and coke, combinations of single-type carbon sources with machine-made char, and trace amounts of phosphorus doping. There are also records of using anthracite, coke, and machine-made char as individual ternary carbon sources. However, no technical solution has been found that combines anthracite, coke, and machine-made char as a ternary composite carbon source with a high proportion of industrial yellow phosphorus or glassy phosphorus slag from yellow phosphorus smelting, employing a fully dry mixing process, low-temperature pre-oxidation, and segmented high-temperature carbonization to prepare hard carbon anode materials. Existing phosphorus modification technologies mostly use trace amounts of chemical reagents such as phosphates and red phosphorus for doping, resulting in low phosphorus source additions, and primarily employ wet preparation processes. Yellow phosphorus slag is also mostly used in building materials and lithium iron phosphate cathode materials, not in hard carbon anode modification. This invention breaks through the limitations of existing technologies in terms of raw material combinations, proportions, and process routes. The overall solution possesses substantial characteristics that distinguish it from existing technologies, while achieving superior comprehensive performance and meeting the inventiveness requirements of an invention patent.

Claims

1. A preparation process for a phosphorus source and phosphorus slag modified hard carbon anode material, characterized in that, It includes two independently implementable technical solutions, and the raw materials are not geographically limited and can be procured through general industrial processes. Option 1: Using industrial yellow phosphorus ore as the core modifying component, combined with a composite carbon source, to prepare modified hard carbon anode materials; Option 2: Using vitreous phosphorus slag from yellow phosphorus ore smelting as the core modifying component, after acid washing to remove impurities, it is combined with a composite carbon source to prepare phosphorus-silicon co-doped hard carbon anode material; The composite carbon source is composed of anthracite, coke, and machine-made charcoal, and does not contain natural wood charcoal raw materials.

2. The manufacturing process of claim 1, wherein, The raw material ratio for Option 1 is: 20%–40% industrial yellow phosphorus and 60%–80% composite carbon source; The internal mass ratio of the composite carbon source is: 40%–60% anthracite, 20%–35% coke, and 10%–25% machine-made charcoal.

3. The preparation process according to claim 1, characterized in that, Option 2 uses the following raw material ratio: 25%–45% pickled yellow phosphorus slag and 55%–75% composite carbon source; The internal mass ratio of the composite carbon source is: 40%–60% anthracite, 20%–35% coke, and 10%–25% machine-made charcoal.

4. The preparation process according to claim 1, characterized in that, The pretreatment process for the vitreous phosphorus slag from yellow phosphorus smelting is as follows: dilute acid immersion is used to remove impurities such as free calcium, fluorine, and iron, while retaining the effective components of phosphorus and silicon and the mineral vitreous skeleton structure.

5. The preparation process according to claim 1, characterized in that, The preparation steps include: raw material crushing and screening, uniform mixing, low-temperature pre-oxidation treatment, inert atmosphere segmented high-temperature carbonization, cooling and pulverizing, and graded impurity removal to obtain the finished hard carbon anode material.

6. The preparation process according to claim 5, characterized in that, The low-temperature pre-oxidation temperature is 200-350℃, and the holding time is 30-90 minutes. It is used to stabilize the raw material structure and reduce carbonization volatilization loss.

7. The preparation process according to claim 5, characterized in that, The segmented high-temperature carbonization uses a nitrogen inert atmosphere. The first stage carbonization temperature is 600-800℃, the second stage carbonization temperature is 900-1200℃, and the total holding time is 2-4 hours.

8. A phosphorus source and phosphorus slag modified hard carbon anode material, characterized in that, This material is used in the anode fields of lithium-ion batteries, sodium-ion batteries, and electrochemical energy storage batteries. Prepared by the process described in any one of claims 1-7, the material forms a high-proportion phosphorus-doped porous structure or a phosphorus-silicon co-doped mineral support composite structure inside. In actual production, the proportioning parameters and temperature control time can be adjusted within a limited range.

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