Negative electrode material of secondary battery as well as preparation method and application of negative electrode material
By designing silicon-phosphorus carbon materials containing cores and multi-layer encapsulation structures, the conductivity and cycle stability of silicon-based anode materials are solved, and a negative electrode material with high capacity and long cycle life is achieved.
Patent Information
- Application Number
- CN202510678084.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2025-08-08
AI Technical Summary
The current carbon (graphite hard carbon) anode materials have a low gram-specific capacity, and the silicon-based anode changes in volume during charging and discharging, resulting in insufficient cycle stability.
By designing a negative electrode material that includes a core and a main silicon phosphorus carbon layer, a main silicon phosphorus layer, a main phosphorus carbon layer, a main silicon silicon layer, and a main carbon layer wrapped around the surface of the core, the conductivity is enhanced by phosphorus doping and hindering the growth of lithium crystal branches, each layer structure is formed using a specific temperature and gas reaction process.
The conductivity and cycle stability of the negative electrode material are improved, and the cycle capacity and number of times are enhanced.
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of secondary batteries, and in particular relates to a negative electrode material and a manufacturing method and application thereof. Background Art
[0002] Carbon (graphite hard carbon) anodes are currently the most commercially mature anodes in secondary batteries, offering excellent conductivity and cycling stability. However, their gram-to-gram capacity is relatively low. Silicon, with its high theoretical capacity, abundant resources, and low cost, holds great promise for replacing carbon (graphite hard carbon) anodes for large-scale commercialization. However, before commercialization can be achieved, silicon must overcome the significant volume change (~300%) during charge and discharge. To address this issue with silicon anodes, researchers have explored several approaches: first, nanoscaling silicon-based materials to mitigate the impact of volume expansion on battery performance; and second, combining silicon with other materials. However, these modifications have yielded limited results, and the cycling stability of the resulting silicon-based anodes remains to be improved. Summary of the Invention
[0003] The present invention aims to address the key issues in the above-mentioned prior art. To this end, the present invention proposes a negative electrode material that, through structural and compositional design, significantly improves the cycling stability of silicon-based or silicon-carbon negative electrodes while maintaining high capacity.
[0004] The present invention selects the optimal temperature, at which the silicon source gas and the carbon source gas are cracked to generate atomic hydrogen.
[0005] At this temperature, hydrogen reacts with the phosphorus source to generate phosphorus atoms, which then penetrate and dope with silicon and carbon.
[0006] At this temperature, other impurities are volatilized and eliminated.
[0007] The advantage of the present invention is that the conductivity of the material is enhanced by utilizing the semiconductor effect through phosphorus doping.
[0008] At the same time, due to doping, the electrostatic field of the material is distorted, which hinders the generation and development of lithium dendrites.
[0009] Due to the above two characteristics, the conductivity, cycle capacity and number of negative electrode materials are greatly improved.
[0010] A negative electrode material, characterized in that it includes an inner core and at least one of a main silicon phosphorus carbon layer A, a main silicon phosphorus layer B, a main phosphorus carbon layer C, a main silicon layer D, and a main carbon layer E wrapped around the surface of the inner core.
[0011] The core can be made of any suitable particle size and any suitable material.
[0012] The inner core may be made of porous carbon, carbon fiber, pure silicon particles, etc. with appropriate particle size and specific surface area.
[0013] The main silicon phosphorus carbon layer A, the main silicon phosphorus layer B, the main phosphorus carbon layer C, the main silicon layer D, and the main carbon layer E can be prepared by a preparation method comprising the following steps.
[0014] The S1 main silicon-phosphorus-carbon layer A is produced in any suitable equipment (such as a fluidized bed, rotary kiln, tunnel kiln, etc.) by mixing a core material with a phosphorus source X, introducing scientifically calculated flow rates of silicon source gas, carbon source gas, and inert gas, and then undergoing a heating, holding, reaction, and cooling process. Due to process requirements or inaccurate calculations, transition layers and pure carbon coatings of varying thickness may exist within and outside this layer. The desired composition and structure can be achieved by selecting the appropriate particle size and weight of the phosphorus source X and repeatedly adding the phosphorus source X.
[0015] The S2 main silicon-phosphorus layer B is produced in any suitable equipment (such as a fluidized bed, rotary kiln, tunnel kiln, etc.) by mixing a core material with a phosphorus source X, introducing a scientifically calculated flow rate of silicon source gas and inert gas, and then undergoing a heating, holding, reaction, and cooling process. Due to process requirements or inaccurate calculations, transition layers of varying thickness may exist within and outside this layer. The desired composition and structure can be achieved by selecting the appropriate particle size and weight of the phosphorus source X and repeatedly adding the phosphorus source X.
[0016] The S3 main phosphorus-carbon layer C is produced in any suitable equipment (such as a fluidized bed, rotary kiln, tunnel kiln, etc.) by mixing a core (inner layer) material of appropriate particle size with a phosphorus source X, introducing a scientifically calculated flow rate of carbon source gas and inert gas, and then undergoing a heating, holding reaction, and cooling process. Due to process requirements or inaccurate calculations, transition layers and pure carbon coating layers of varying thickness may exist within and outside this layer. The desired composition and structure can be achieved by selecting the appropriate particle size and weight of the phosphorus source X and repeatedly adding the phosphorus source X.
[0017] The S4 main silicon layer D is produced in any suitable equipment (such as a fluidized bed, rotary kiln, tunnel kiln, etc.) using a material of suitable particle size that can serve as the core, introducing a scientifically calculated flow rate of silicon source gas and inert gas, and undergoing a heating, insulation reaction, and cooling process. Alternatively, the outer layer can be directly made of silicon particles of suitable particle size.
[0018] The S5 main carbon layer E is produced in any suitable equipment (such as fluidized bed, rotary kiln, tunnel kiln, etc.) by using materials with suitable particle size that can serve as the core (inner layer), introducing a certain flow rate of carbon source gas and inert gas that has been scientifically calculated, and undergoing a process of heating, heat preservation, reaction, and cooling.
[0019] The inner layer refers to one or more A, B, C, D, and E layers deposited on the outer surface of the inner core by vapor deposition.
[0020] The negative electrode material is characterized in that the phosphorus source X includes one or more of sodium hexametaphosphate, potassium hexametaphosphate, calcium hexametaphosphate, sodium tri(poly)polyphosphate, potassium tri(poly)polyphosphate, calcium tri(poly)polyphosphate, sodium pyrophosphate, potassium pyrophosphate, calcium pyrophosphate, sodium metaphosphate, potassium metaphosphate, calcium metaphosphate, sodium phosphate, potassium phosphate, and calcium phosphate.
[0021] The negative electrode material is characterized in that the silicon source gas includes one or more of silane, monosilane, and hydrogen.
[0022] The negative electrode material is characterized in that the carbon source gas includes one or more of acetylene, methane, ethylene, and hydrogen.
[0023] The negative electrode material is characterized in that the S1S2S3 insulation reaction temperature is 560-660 degrees.
[0024] The negative electrode material is characterized in that the S1S4S5 insulation reaction temperature is 500-650 degrees.
[0025] The negative electrode material is characterized in that the main silicon-phosphorus-carbon layer A is composed of 30-100 parts of silicon, 0.01-50 parts of phosphorus, and 1-60 parts of carbon by weight.
[0026] The negative electrode material is characterized in that the main silicon-phosphorus layer B comprises 1-100 parts of silicon and 0.01-50 parts of phosphorus by weight.
[0027] The negative electrode material is characterized in that the main phosphorus-carbon layer C comprises 0.01-60 parts by weight of phosphorus and 1-100 parts of carbon.
[0028] The negative electrode material according to claim 1 is characterized in that a transition layer formed by the mutual penetration of phosphorus, silicon and carbon exists between the main layers and between the main layers and the core.
[0029] The so-called inert gas refers to nitrogen and argon.
[0030] (1) A method for manufacturing a negative electrode structure of: core + main body A layer, or core + main body A layer + main body C layer, or core + main body A layer + main body E layer.
[0031] A material of suitable particle size and weight (eg, 1000 grams) is selected as the core, and its composition is at least but not limited to one of the following materials: porous carbon, carbon fiber, and graphite.
[0032] Mix the material with an appropriate particle size and weight (e.g., 60 g) and place it in a fluidized bed (rotary kiln or tunnel kiln). Raise the temperature at a rate of 5-10°C / min to 560-700°C while introducing an inert gas at a constant flow rate (e.g., 0.5-15 L / min). At 560-700°C, introduce an inert gas at a constant flow rate (e.g., 0.5-30 L / min), silane gas (e.g., 1-20 L / min), and acetylene gas (e.g., 0.5-20 L / min). The reaction time is 100-800 minutes.
[0033] Then, the silane valve was closed to stop the introduction of silane, and acetylene was continued to be introduced for another 0-400 minutes.
[0034] Depending on the amount of X, the flow rate of silane and acetylene and the length of time of introduction, negative electrode materials with different layered structures such as core + main body A layer, core + main body A layer + main body C layer, or core + main body A layer + main body E layer can be produced.
[0035] (2) A method for manufacturing a negative electrode structure of: core + main body B layer or core + main body B layer + main body C layer or core + main body B layer + main body E layer.
[0036] A material of suitable particle size and weight (eg, 1000 grams) is selected as the core, and its composition is at least but not limited to one of the following materials: porous carbon, carbon fiber, and graphite.
[0037] Mix the material with X of appropriate particle size and weight (e.g., 60 grams) and place it in a fluidized bed (rotary kiln or tunnel kiln). Inert gas is introduced at a constant flow rate (e.g., 0.5-20 L / min). The temperature is raised at a rate of 2-20°C / min to 550-680°C. At 550-680°C, inert gas and silane gas are introduced at a constant flow rate (e.g., 0.5-20 L / min) and 1-20 L / min, respectively. The reaction time is 100-400 minutes.
[0038] Then, stop introducing silane, continue to raise the temperature to 580-700 degrees, open the acetylene valve, and introduce acetylene at a certain flow rate (for example, 0.5-20 liters / minute), and the reaction time is 0-400 minutes.
[0039] Depending on the amount of X, the flow rate of silane and acetylene and the length of time of introduction, negative electrode materials with different layered structures such as core + main body B layer, core + main body B layer + main body C layer or core + main body B layer + main body E layer can be produced.
[0040] (3) Manufacturing method of core + main body B layer + main body E layer + main body C layer.
[0041] The prepared core + body B layer + body E layer material is cooled, and X of appropriate particle size and weight (e.g., 50 g) is added again. The temperature is raised to 580-700 degrees at a rate of 2-10 degrees per minute. At this temperature, a certain flow rate of inert gas and carbon source gas is introduced. The reaction time is 1-600 minutes.
[0042] (4) The negative electrode structure is: core + main body D layer + main body C layer.
[0043] A material with a suitable particle size and a suitable weight (eg, 1000 grams) is selected as the core, and its composition is at least but not limited to one of the following materials: porous carbon, carbon fiber, and graphite.
[0044] The above materials are placed in a fluidized bed (rotary kiln or tunnel kiln) and inert gas is introduced at a constant flow rate (e.g., 0.5-20 L / min). The temperature is raised at a rate of 2-20°C / min to 530-650°C. At 530-650°C, inert gas is introduced at a constant flow rate (e.g., 0.5-30 L / min) and silane gas (e.g., 1-20 L / min). The reaction is continued for 10-400 minutes. The temperature is then cooled to room temperature.
[0045] Mix the above materials with an appropriate particle size and weight (e.g., 60 g) and place them in a fluidized bed (rotary kiln or tunnel kiln). Inert gas is introduced at a constant flow rate (e.g., 0.5-20 L / min). The temperature is raised at a rate of 2-20°C / min to 560-700°C. At 560-700°C, inert gas is introduced at a constant flow rate (e.g., 0.5-20 L / min), acetylene gas is introduced at a constant flow rate (e.g., 1-12 L / min), and finally acetylene gas (e.g., 0.5-20 L / min). The reaction time is 100-400 minutes.
[0046] Depending on the amount of X, the flow rate of silane and acetylene and the length of time of introduction, a negative electrode material with a core + main body D layer + main body C layer structure can be produced.
[0047] (5) A method for manufacturing a negative electrode structure of: core + main body D layer + main body E layer + main body C layer.
[0048] A material of suitable particle size and weight (eg, 1000 grams) is selected as the core, and its composition is at least but not limited to one of the following materials: porous carbon, carbon fiber, and graphite.
[0049] The above materials are placed in a fluidized bed (rotary kiln or tunnel kiln), and inert gas is introduced at a constant flow rate (e.g., 0.5-20 L / min). The temperature is raised at a rate of 2-20°C / min to 500-650°C. At 500-650°C, inert gas and silane gas are introduced at a constant flow rate (e.g., 0.5-20 L / min) and 1-20 L / min, respectively. The reaction time is 10-400 minutes. Then, the silane valve is closed and the temperature is raised to 580-700°C. Acetylene and inert gas are introduced at a constant flow rate (e.g., 0.5-20 L / min) and 0.5-20 L / min, respectively, for a reaction time of 10-500 minutes.
[0050] The material of
[0049] is cooled to room temperature, mixed with X of suitable particle size and weight (e.g., 50 g), heated to 580-700 degrees, and a certain flow rate (e.g., 0.5-20 L / min) of acetylene and a certain flow rate (e.g., 0.5-20 L / min) of inert gas are introduced, and the reaction time is 1-500 minutes.
[0051] Depending on the amount of X, the flow rate of silane and acetylene and the length of time of introduction, a negative electrode material with a layered structure of core + main body D layer + main body E layer + main body C layer can be produced.
[0052] (6) The negative electrode structure is: pure silicon particles + main E layer + main C layer.
[0053] Silicon particles of appropriate size and weight (e.g., 1000 g) are placed in a fluidized bed (rotary kiln or tunnel kiln), heated to 550-700°C, and acetylene and inert gas are introduced at a certain flow rate (e.g., 0.5-20 L / min) for 1-500 minutes.
[0054] The material of
[0053] is cooled to room temperature, mixed with X of appropriate particle size and weight (e.g. 60 g), heated to 580-800 degrees, and a certain flow rate of acetylene and inert gas is introduced, and the reaction time is 1-500 minutes.
[0055] Depending on the amount of X, the flow rate of silane and acetylene and the length of time of introduction, a negative electrode material with a layered structure of pure silicon particles + main E layer + main C layer can be produced.
[0056] (7) The negative electrode structure is: pure silicon particles + main C layer manufacturing method.
[0057] A material of suitable particle size and weight (eg, 1000 grams) is selected as the core, and its composition is at least but not limited to one of the following materials: porous carbon, carbon fiber, and graphite.
[0058] The above materials are mixed with X of appropriate particle size and weight (e.g., 50 g) and placed in a fluidized bed (rotary kiln or tunnel kiln). Inert gas is introduced at a constant flow rate (e.g., 0.5-20 L / min). The temperature is raised at a rate of 2-20°C / min to 560-700°C. At 560-700°C, inert gas and acetylene are introduced at a constant flow rate (e.g., 0.5-20 L / min) for 1-800 minutes.
[0059] The reacted material was cooled to room temperature.
[0060] Depending on the amount of X, the flow rate of acetylene and the length of time it is introduced, a negative electrode material with a pure silicon particle + main C layer structure can be produced.
[0061] Example 1: kernel + main body B layer + main body C layer.
[0062] 1000 g of porous carbon of appropriate particle size was mixed with 100 g of X of appropriate particle size, placed in a rotary kiln, and heated to 620°C at a rate of 10°C per minute. Within the 620°C temperature range, silane was introduced at a rate of 3 liters per minute for 200 minutes.
[0063] Stop the silane flow and instead introduce acetylene at a flow rate of 1.0 liter per minute for 300 minutes, and cool naturally.
[0064] Nitrogen was introduced during the heating, keeping and cooling processes at a flow rate of 1 liter per minute.
[0065] The surface area of porous carbon can be 1-900.
[0066] It should be noted that the present application is not limited to the above-mentioned embodiments. The implementation methods that have the same structure and the same effect as the technical idea within the scope of the technical solution include In addition, without departing from the scope of the present invention, the embodiments may be modified by applying the technology of the art. Various modifications that can be conceived by human resources and other forms constructed by combining some of the components in the embodiments are also possible. Included within the scope of this application.
[0067] Example 1 Cycle capacity mAh / g Cycle times 1680 500
Claims
1. A negative electrode material, characterized in that The invention comprises an inner core and one or more of the following: a main silicon-phosphorus-carbon layer A, a main silicon-phosphorus layer B, a main phosphorus-carbon layer C, a main silicon layer D, and a main carbon layer E, coating the inner core. The inner core can be made of any suitable particle size and material. Porous carbon, carbon fibers, pure silicon particles, and the like with suitable particle size and specific surface area can be used. The main silicon-phosphorus-carbon layer A, main silicon-phosphorus layer B, main phosphorus-carbon layer C, main silicon layer D, and main carbon layer E can be prepared by a preparation method comprising the following steps. The main silicon-phosphorus-carbon layer A is prepared in any suitable apparatus (e.g., a fluidized bed, rotary kiln, tunnel kiln, etc.) by mixing a material that can serve as the inner core with a phosphorus source X, introducing a scientifically calculated flow rate of silicon source gas, carbon source gas, and an inert gas, followed by a heating, holding reaction, and cooling process. Due to process requirements or inaccurate calculations, transition layers and pure carbon coating layers of varying thickness may exist within and outside the layer. By selecting a phosphorus source X with an appropriate particle size and weight, and repeatedly adding the phosphorus source X, the desired composition and structure can be achieved. The main silicon-phosphorus layer S2, B, is produced in any suitable apparatus (such as a fluidized bed, rotary kiln, tunnel kiln, etc.) by mixing a material that can serve as the core with the phosphorus source X, introducing a scientifically calculated flow rate of silicon source gas and an inert gas, and then heating, holding, reacting, and cooling. Due to process requirements or inaccurate calculations, transition layers of varying thickness may exist within and outside this layer. By selecting a phosphorus source X with an appropriate particle size and weight, and repeatedly adding the phosphorus source X, the desired composition and structure can be achieved. The main phosphorus-carbon layer S3, C, is produced in any suitable apparatus (such as a fluidized bed, rotary kiln, tunnel kiln, etc.) by mixing a material that can serve as the core (inner layer) with an appropriate particle size and the phosphorus source X, and introducing a scientifically calculated flow rate of carbon source gas and an inert gas, and then heating, holding, reacting, and cooling. Due to process requirements or inaccurate calculations, transition layers and pure carbon coatings of varying thickness may exist within and outside this layer. This can be achieved by selecting a phosphorus source X of appropriate particle size and weight, and by repeatedly adding the phosphorus source X, to achieve a composition and structure that meets the design. The main silicon layer S4, D, is produced in any suitable equipment (such as a fluidized bed, rotary kiln, or tunnel kiln) by introducing a silicon source gas and an inert gas at a scientifically calculated flow rate, followed by heating, holding, reaction, and cooling. Alternatively, the outer layer can be directly produced using silicon particles of an appropriate particle size. The main carbon layer S5, E, is produced in any suitable equipment (such as a fluidized bed, rotary kiln, or tunnel kiln) by introducing a carbon source gas and an inert gas at a scientifically calculated flow rate, followed by heating, holding, reaction, and cooling. The inner layer refers to one or more layers A, B, C, D, and E deposited on the outer surface of the core by vapor deposition or other methods.
2. The negative electrode material according to claim 1, characterized in that The phosphorus source X includes one or more of sodium hexametaphosphate, potassium hexametaphosphate, calcium hexametaphosphate, sodium tri(poly)polyphosphate, potassium tri(poly)polyphosphate, calcium tri(poly)polyphosphate, sodium pyrophosphate, potassium pyrophosphate, calcium pyrophosphate, sodium metaphosphate, potassium metaphosphate, calcium metaphosphate, sodium phosphate, potassium phosphate, and calcium phosphate.
3. The negative electrode material according to claim 1, characterized in that The silicon source gas includes one or more of silane, monosilane, disilane, and hydrogen.
4. The negative electrode material according to claim 1, characterized in that The carbon source gas includes one or more of acetylene, methane, ethane, and hydrogen.
5. The negative electrode material according to claim 1, characterized in that The S1S2S3 insulation reaction temperature is 560-660 degrees.
6. The negative electrode material according to claim 1, characterized in that The S1S4S5 insulation reaction temperature is 500-650 degrees.
7. The negative electrode material according to claim 1, characterized in that The weight composition of the main silicon-phosphorus-carbon layer A can be determined by theoretical calculation or measurement method, which is 30-100 parts of silicon, 0.01-50 parts of phosphorus, and 1-60 parts of carbon.
8. The negative electrode material according to claim 1, characterized in that The weight composition of the main silicon-phosphorus layer B can be determined by theoretical calculation or measurement method, which is 1-100 parts of silicon and 0.01-50 parts of phosphorus.
9. The negative electrode material according to claim 1, characterized in that The weight composition of the main phosphorus-carbon layer C can be determined by theoretical calculation or measurement method, which is 0.01-60 parts of phosphorus and 1-100 parts of carbon.
10. The negative electrode material according to claim 1, characterized in that There is a transition layer between the main layers and between the main layer and the inner core, which is caused by the mutual penetration of phosphorus, silicon and carbon.