Coffee grounds-based carbon negative electrode material and preparation method and application thereof

Abstract

The application provides a coffee residue-based carbon negative electrode material and a preparation method and application thereof. The preparation method comprises the following steps: S1, performing first drying treatment on coffee residue to obtain a coffee residue precursor; S2, mixing the coffee residue precursor with iron powder to obtain a carbide precursor, and performing calcination treatment on the carbide precursor under an inert gas atmosphere to obtain a carbonization product; and S3, sequentially performing acid pickling treatment, suction filtration treatment and second drying treatment on the carbonization product to obtain a coffee residue-based negative electrode material. The preparation method in the above scheme solves the technical problems of low capacity and poor cycle stability of the biomass carbon material in the prior art.

Description

Technical Field

[0001] This invention relates to the technical field of lithium-ion batteries, and more specifically, to a coffee grounds-based carbon anode material, its preparation method, and its application. Background Technology

[0002] In the field of lithium-ion battery anode materials, carbon-based materials have become the mainstream anode choice due to their advantages such as low cost, high chemical stability, and excellent cycle performance. Currently, natural graphite and artificial graphite are the most widely used in industry, but their raw materials rely on non-renewable petroleum or coal tar resources, and their preparation processes are energy-intensive and heavily polluting, making it difficult to meet the strategic needs of sustainable development. In recent years, biomass-derived carbon materials have been widely regarded as potential candidates for next-generation green carbon anodes due to their wide availability, renewability, environmental friendliness, and rich heteroatoms (such as N, O, and P).

[0003] In existing technologies, biomass carbon materials generally suffer from structural defects: their carbon skeletons are mostly highly disordered hard carbon structures with low crystallinity and low graphite microcrystal content, resulting in poor electronic conductivity and slow ion diffusion kinetics, which limits the capacity utilization and cycle stability of the materials under high-rate charge and discharge conditions.

[0004] There is currently no effective solution to the technical problems of low capacity and poor cycle stability of biomass carbon materials in existing technologies. Summary of the Invention

[0005] The main objective of this invention is to provide a coffee grounds-based carbon anode material, its preparation method, and its application, in order to solve the technical problems of low capacity and poor cycle stability of biomass carbon materials in the prior art.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a coffee grounds-based carbon anode material is provided, comprising: step S1, subjecting coffee grounds to a first drying treatment to obtain a coffee grounds precursor; step S2, mixing the coffee grounds precursor with iron powder to obtain a carbide precursor, and calcining the carbide precursor under an inert gas atmosphere to obtain a carbonized product; and step S3, sequentially subjecting the carbonized product to acid washing, filtration, and a second drying treatment to obtain the coffee grounds-based anode material.

[0007] Furthermore, in step S2, the mass ratio of coffee grounds precursor to iron powder is (6:1) to (1:1).

[0008] Furthermore, in step S2, the calcination treatment is carried out under an inert gas atmosphere, the calcination temperature is 600~1300℃, and the calcination time is 1~5h.

[0009] Furthermore, in step S3, the inorganic acid used for pickling is hydrochloric acid or nitric acid, and the concentration of the inorganic acid is 1~3 mol / L.

[0010] Furthermore, in step S3, the pickling time for the pickling process is 46~50 hours.

[0011] Further, in step S2, the coffee grounds precursor is mixed with iron powder to obtain a carbide precursor, including: shaking the mixture of coffee grounds precursor and iron powder; and grinding the mixture after shaking to obtain the carbide precursor.

[0012] Furthermore, the oscillation time of the oscillation treatment and the grinding time of the grinding treatment are each independently 0.5~2h.

[0013] Furthermore, the drying temperature of the first drying treatment in step S1 and the drying temperature of the second drying treatment in step S3 are each independently 60~90℃, and the drying time of the first drying treatment in step S1 and the drying time of the second drying treatment in step S3 are each independently 10~14h.

[0014] According to another aspect of the present invention, a coffee grounds-based carbon anode material is provided, which is prepared by the above-described preparation method.

[0015] According to another aspect of the present invention, a lithium-ion battery is provided, comprising a positive electrode and a negative electrode, wherein the negative electrode comprises the above-mentioned coffee grounds-based carbon negative electrode material.

[0016] By applying the technical solution of this invention, coffee grounds are dried to remove free moisture and some volatile organic components, ensuring the stability and controllability of the subsequent carbonization process and preventing particle bursting, structural collapse, or uneven agglomeration during carbonization. Under the catalytic action of iron powder, the disordered carbon skeleton of the coffee grounds precursor undergoes localized graphitization and reconstruction at relatively low temperatures, forming a graphite microcrystalline network with a short-range ordered structure. This graphite microcrystalline network enhances the electronic conductivity of the material and promotes the rapid diffusion of lithium ions within the particles, thereby effectively improving... The material exhibits high reversible specific capacity and rate performance. Simultaneously, iron catalysis lowers the carbonization temperature, avoiding excessive sintering and collapse of the natural pore structure of biomass during high-temperature treatment. This allows the material to retain abundant micropores and mesopores while achieving improved conductivity, providing ample storage sites and transport channels for lithium ions. The carbonization product undergoes synergistic treatment via acid washing and filtration to effectively remove residual iron and iron oxides, fundamentally eliminating the risk of metallic impurities catalyzing electrolyte decomposition, triggering irreversible side reactions, and causing continuous growth of solid electrolyte interfacial films during electrochemical cycling. This suppresses capacity decay and improves cycle life. The preparation method described above solves the technical problems of low capacity and poor cycle stability in existing biomass carbon materials. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A flowchart of the method for preparing coffee grounds-based carbon anode material in this application is shown;

[0019] Figure 2 The XRD pattern of the coffee grounds-based carbon anode material in this application is shown;

[0020] Figure 3 The charge-discharge curves of the coffee grounds-based carbon anode material in this application are shown. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and therefore their description will be omitted.

[0025] As analyzed in the background section, existing biomass carbon materials suffer from low capacity and poor cycle stability. To address these issues, this application provides a coffee grounds-based carbon anode material, its preparation method, and its application.

[0026] Carbon materials derived from biomass precursors possess abundant nanopores and large surface areas, which are beneficial for ion insertion and adsorption. Furthermore, naturally occurring heteroatoms in biomass (such as nitrogen and phosphorus) can self-dopat during carbonization, further enhancing ion storage capacity. However, the disordered microstructure of carbon materials also leads to poor conductivity and cycle stability, posing a significant challenge for battery applications. Catalytic graphitization can introduce highly conductive graphite structures into biomass-derived hard carbon, ensuring effective ion diffusion and rapid electron transfer, thereby achieving high capacity and stability.

[0027] In a typical embodiment of this application, combined with Figure 1 As shown in the specific embodiments of this application, a method for preparing a coffee grounds-based carbon anode material is provided, the method comprising the following steps:

[0028] Step S1: The coffee grounds are subjected to a first drying process to obtain coffee grounds precursor.

[0029] Step S2: The coffee grounds precursor is mixed with iron powder to obtain a carbide precursor, and the carbide precursor is calcined under an inert gas atmosphere to obtain a carbonized product.

[0030] Step S3 involves sequentially performing acid washing, filtration, and a second drying process on the carbonized product to obtain coffee grounds-based anode material.

[0031] In the embodiments of this application, coffee grounds are dried to remove free moisture and some volatile organic components from the raw material, ensuring the stability and controllability of the subsequent carbonization process and preventing particle bursting, structural collapse, or uneven agglomeration during carbonization. Under the catalytic action of iron powder, the disordered carbon skeleton of the coffee grounds precursor undergoes localized graphitization and reconstruction at relatively low temperatures, forming a graphite microcrystalline network with a short-range ordered structure. This graphite microcrystalline network enhances the electronic conductivity of the material and promotes the rapid diffusion of lithium ions within the particles, thereby effectively improving... The material exhibits reversible specific capacity and rate performance. Simultaneously, iron catalysis lowers the carbonization temperature, avoiding excessive sintering and collapse of the biomass' natural pore structure during high-temperature processing. This allows the material to retain abundant micropores and mesopores while achieving improved conductivity, providing ample storage sites and transport channels for lithium ions. The carbonization products are treated with a combination of acid washing and filtration to effectively remove residual iron and iron oxides, fundamentally eliminating the risk of metallic impurities catalyzing electrolyte decomposition, triggering irreversible side reactions, and causing continuous growth of solid electrolyte interfacial films during electrochemical cycling. This suppresses capacity decay and improves cycle life. The preparation method described above solves the technical problems of low capacity and poor cycle stability in existing biomass carbon materials.

[0032] In one embodiment of this application, in step S2, the mass ratio of coffee grounds precursor to iron powder is (6:1) to (1:1).

[0033] In the embodiments of this application, the mass ratio of coffee grounds precursor to iron powder is controlled within the range of (6:1) to (1:1). This ensures carbon atom rearrangement and the formation of graphite microcrystals to improve electron conduction and ion migration rates, while avoiding excessive graphitization of the carbon skeleton due to excessive catalyst, resulting in partial collapse of the pore structure, a decrease in specific surface area, and a reduction in reversible lithium-ion insertion sites. Simultaneously, it avoids excessive iron powder leading to more residual iron after acid washing, which could potentially trigger electrolyte decomposition, irreversible solid electrolyte interfacial film formation, and interfacial polarization. Maintaining the mass ratio within the aforementioned range helps to achieve comprehensive optimization of material capacity, rate performance, and cycle stability.

[0034] In one embodiment of this application, in step S2, the calcination process is carried out under an inert gas atmosphere, the calcination temperature is 600~1300℃, and the calcination time is 1~5h.

[0035] In the embodiments of this application, calcination is performed under an inert gas atmosphere to isolate oxygen and prevent oxidation, combustion, or structural damage of the carbon precursor during high-temperature pyrolysis. This ensures that the carbonization reaction proceeds in a controllable and directional manner to obtain a carbon material with a complete structure and stable performance. By controlling the calcination temperature within the range of 600~1300℃ and the calcination time within the range of 1~5h, efficient graphitization can be achieved in the low-temperature region through iron powder catalysis, breaking through the bottleneck of low conductivity of traditional biomass carbon. At the same time, the damage to the pore structure and the aggravation of impurity residue caused by high temperature are avoided, achieving the optimal coupling between controllable structure, improved conductivity, and retention of lithium storage space.

[0036] In one embodiment of this application, in step S3, the inorganic acid used for pickling is hydrochloric acid or nitric acid, and the concentration of the inorganic acid is 1~3 mol / L.

[0037] In the embodiments of this application, during the carbonization process, iron powder is uniformly dispersed in the carbon framework as a catalyst. Although it effectively promotes the formation of graphite microcrystals at high temperatures, in electrochemical applications, the residual metallic iron or its oxides have strong catalytic activity, which continuously triggers the reduction and decomposition of the electrolyte, leading to abnormal thickening of the solid electrolyte interface film, increased irreversible lithium-ion loss, and increased interface polarization, severely damaging the battery's first-cycle coulombic efficiency and long-term cycle stability. Using hydrochloric acid or nitric acid as the acid washing reagent, and controlling the acid concentration within the range of 1~3 mol / L, can dissolve iron and its oxides at a sufficiently fast rate, while having a negligible impact on the microstructure, pore structure, and surface chemical composition of the carbon material, maintaining stable specific surface area and pore volume, and ensuring the high reactivity of the material and the integrity of the ion transport channels.

[0038] In one embodiment of this application, in step S3, the pickling time is 46-50 hours.

[0039] In the embodiments of this application, iron powder is uniformly dispersed in the carbon skeleton as a catalyst, which effectively promotes the formation of graphite microcrystals. However, its distribution inside the carbon matrix is ​​not completely exposed on the surface. Some iron particles are wrapped by the carbon layer or form a stable iron carbide phase with carbon. The structure is dense and the chemical inertness is enhanced. By controlling the pickling time within the range of 46 to 50 hours, it is sufficient for the acid to complete the multi-level diffusion from the material surface to the internal micro-regions, gradually dissolving the residual elemental iron, iron oxide and iron carbide phase. That is, it selectively dissolves only metallic impurities, and has basically no destructive effect on the pore structure, specific surface area, surface functional groups and heteroatom doping of the carbon material.

[0040] In one embodiment of this application, step S2, mixing coffee grounds precursor with iron powder to obtain a carbide precursor, includes: subjecting the mixture of coffee grounds precursor and iron powder to vibration treatment; and subjecting the mixture after vibration treatment to grinding treatment to obtain a carbide precursor.

[0041] In the embodiments of this application, the coffee grounds precursor is porous, fibrous, and heterogeneous, with a wide particle size distribution and rich in organic functional groups and residual moisture on the surface. The iron powder is a metal powder with high particle density, easy agglomeration, and large surface energy. Under conventional dry mixing or simple stirring conditions, it is very easy to form local iron-rich clusters or poorly uniform point distributions. As a result, during the subsequent high-temperature carbonization process, the catalytic reaction only occurs in local areas, while the remaining areas still maintain a highly disordered hard carbon structure. This uneven catalyst distribution not only significantly reduces the formation efficiency of graphite microcrystals, but also causes the internal conductive network of the material to break and the lithium-ion transport channels to be blocked, ultimately resulting in low capacity, poor rate performance, and short cycle life. The mixture of coffee grounds precursor and iron powder is shaken to break up the agglomeration of iron powder particles and promote the initial dispersion of iron powder particles in the pores and fiber gaps of coffee grounds. The shaken mixture is then ground to further break the iron powder into nano or submicron particles, thereby increasing the interfacial contact area between the iron particles and the carbon source. This allows the iron powder to anchor itself near the potential graphitization sites of the carbon skeleton in a highly dispersed active site form, ensuring that catalytic nucleation and graphitization growth can occur synchronously, continuously, and over a large area during the subsequent carbonization process, rather than in a localized burst.

[0042] In one embodiment of this application, the oscillation duration of the oscillation treatment and the grinding duration of the grinding treatment are each independently 0.5~2h.

[0043] In the embodiments of this application, the oscillation time is controlled at 0.5~2h and the grinding time is controlled at 0.5~2h. Without destroying the original fibrous structure of the coffee grounds, the iron powder particles are evenly dispersed in the carbon skeleton of the coffee grounds precursor, while avoiding premature non-uniform carbonization caused by local temperature rise.

[0044] In one embodiment of this application, the drying temperature of the first drying process in step S1 and the drying temperature of the second drying process in step S3 are each independently 60~90°C, and the drying time of the first drying process in step S1 and the drying time of the second drying process in step S3 are each independently 10~14h.

[0045] In the embodiments of this application, coffee grounds are dried at a temperature of 60-90°C for 10-14 hours. Moisture migrates from the interior of the particles to the surface through capillary action, preventing structural collapse and gently and thoroughly removing physically adsorbed water and some bound water while preserving the original organic structure and heteroatom composition of the biomass to the maximum extent. The carbonized products after acid washing and filtration are dried at a temperature of 60-90°C for 10-14 hours. Without damaging the formed graphite microcrystalline structure and porous network, residual moisture, ions, and trace amounts of acid are thoroughly removed, preventing these impurities from causing side reactions during subsequent electrode slurry preparation and battery assembly.

[0046] In another typical embodiment of this application, a coffee grounds-based carbon anode material is provided, which is prepared by the preparation method described in the above embodiments.

[0047] In the embodiments of this application, coffee grounds-based carbon anode materials have successfully transformed from agricultural waste into high-performance electrode materials through iron powder catalytic graphitization process: Firstly, a large number of highly graphitized microcrystalline regions are formed in the microstructure of coffee grounds-based carbon anode materials. These graphite microcrystals have significantly increased coherence length along the c-axis direction, making the overall crystallinity of the material significantly higher than that of untreated pure coffee grounds carbon, thereby greatly improving electronic conductivity. Secondly, the material still retains the rich micropore and mesopore network derived from the natural porous structure of coffee grounds. These pores not only provide sufficient lithium-ion storage space, but also create efficient channels for electrolyte penetration and rapid lithium-ion transport.

[0048] In another typical embodiment of this application, a lithium-ion battery is provided, including a positive electrode and a negative electrode, wherein the negative electrode includes the coffee grounds-based carbon negative electrode material in the above embodiments.

[0049] In the embodiments of this application, during the first charging process of the lithium-ion battery, the solid electrolyte interface film formed on the surface of the negative electrode is slightly thicker than that of commercial graphite due to the high specific surface area of ​​the coffee grounds-based carbon negative electrode material. However, thanks to the graphite microcrystalline structure introduced by iron catalysis, the uniformity and ion conductivity of the solid electrolyte interface film are significantly enhanced, effectively suppressing the continuous decomposition of the electrolyte and the irreversible loss of lithium ions in subsequent cycles.

[0050] The beneficial effects of this application will be explained below with reference to specific embodiments and comparative examples.

[0051] Example 1

[0052] Coffee grounds-based carbon anode materials were prepared according to the following steps:

[0053] Step 1: Weigh 5g of coffee grounds and place them in a 70℃ drying oven for 12 hours to remove moisture from the material.

[0054] Step 2: Weigh 0.33g of iron powder and mix it with 2g of the dried coffee grounds from Step 2. Place the mixture in a shaker and shake for 1 hour. Then, pour the shaken mixture into a mortar and grind for 0.5 hours to obtain the carbide precursor.

[0055] Step 3: The carbide precursor obtained in Step 1 is loaded into a crucible and placed in a tube furnace. The temperature is increased to 1100°C at 5°C / min under an argon atmosphere and held at this temperature for 3 hours. Then it is naturally cooled to room temperature to obtain the carbide product.

[0056] Step 4: Place the carbonized product obtained in Step 3 into a beaker, pour in dilute hydrochloric acid and stir for 48 hours. Filter the stirred solution with deionized water and rinse repeatedly to remove residual ions. Finally, place the filtered material into an oven and dry it at 70°C for 12 hours to obtain coffee grounds-based carbon anode material.

[0057] Example 2

[0058] Coffee grounds-based carbon anode materials were prepared according to the following steps:

[0059] Step 1: Weigh 5g of coffee grounds and place them in a 70℃ drying oven for 12 hours to remove moisture from the material.

[0060] Step 2: Weigh 0.5g of iron powder and mix it with 2g of the dried coffee grounds from Step 1. Place the mixture in a shaker and shake for 1 hour. Then, pour the shaken mixture into a mortar and grind for 0.5 hours to obtain the carbide precursor.

[0061] Step 3: The carbide precursor obtained in Step 2 is loaded into a crucible and placed in a tube furnace. The temperature is increased to 1100°C at 5°C / min under an argon atmosphere and held at this temperature for 3 hours. Then it is naturally cooled to room temperature to obtain the carbide product.

[0062] Step 4: Place the carbonized product obtained in Step 3 into a beaker, pour in dilute hydrochloric acid and stir for 48 hours. Filter the stirred solution with deionized water and rinse repeatedly to remove residual ions. Finally, place the filtered material into an oven and dry it at 70°C for 12 hours to obtain coffee grounds-based carbon anode material.

[0063] Example 3

[0064] Coffee grounds-based carbon anode materials were prepared according to the following steps:

[0065] Step 1: Weigh 5g of coffee grounds and place them in a 70℃ drying oven for 12 hours to remove moisture from the material.

[0066] Step 2: Weigh 1g of iron powder and mix it with 2g of the dried coffee grounds from Step 1. Place the mixture in a shaker and shake for 1 hour. Then, pour the shaken mixture into a mortar and grind for 0.5 hours to obtain the carbide precursor.

[0067] Step 3: The carbide precursor obtained in Step 2 is loaded into a crucible and placed in a tube furnace. The temperature is increased to 1100°C at 5°C / min under an argon atmosphere and held at this temperature for 3 hours. Then it is naturally cooled to room temperature to obtain the carbide product.

[0068] Step 4: Place the carbonized product obtained in Step 3 into a beaker, pour in dilute hydrochloric acid and stir for 48 hours. Filter the stirred solution with deionized water and rinse repeatedly to remove residual ions. Finally, place the filtered material into an oven and dry it at 70°C for 12 hours to obtain coffee grounds-based carbon anode material.

[0069] In Examples 1 to 3, by changing the mass ratio of iron powder to coffee grounds while keeping other conditions constant, it was found that the initial charge-discharge capacity of the material increased with the increase of the mass of iron powder, but the initial coulombic efficiency showed a decreasing trend. This is because with the increase of the added iron powder mass, the specific surface area of ​​the material increases, resulting in more exposed active sites and a significant expansion of the electrolyte contact interface. This leads to a substantial increase in the formation of a solid electrolyte interfacial film, causing the initial coulombic efficiency to gradually decrease. In addition, the more iron powder used, the more iron remains after acid washing. The residual iron has catalytic activity and may trigger electrolyte decomposition, irreversible solid electrolyte interfacial film formation, and interfacial polarization, all of which contribute to a further decrease in the initial coulombic efficiency.

[0070] Comparative Example 1

[0071] Coffee grounds-based carbon anode materials were prepared according to the following steps:

[0072] Step 1: Weigh 5g of coffee grounds and place them in a 70℃ drying oven for 12 hours to remove moisture from the material.

[0073] Step 2: Weigh 2g of the dried coffee grounds from Step 1, place them on a shaker and shake for 1 hour, then pour the shaken mixture into a mortar and grind for 0.5 hours to obtain the carbide precursor.

[0074] Step 3: The carbide precursor obtained in Step 2 is loaded into a crucible and placed in a tube furnace. The temperature is increased to 1100°C at 5°C / min under an argon atmosphere and held at this temperature for 3 hours. Then it is naturally cooled to room temperature to obtain the carbide product.

[0075] Step 4: Filter the carbonized product obtained in Step 3 with deionized water and rinse repeatedly; finally, put the filtered material into an oven and dry it at 70°C for 12 hours to obtain coffee grounds-based carbon anode material.

[0076] Example 4

[0077] The negative electrode sheet for lithium-ion batteries is prepared according to the following steps:

[0078] The coffee grounds-based carbon anode materials prepared in Example 1 and Comparative Example 1 were mixed with conductive carbon black and polyvinylidene fluoride at a mass ratio of 8:1:1 to obtain the mixture.

[0079] After grinding the obtained mixture for 30 minutes, add an appropriate amount of N-methylpyrrolidone and grind for another 30 minutes to obtain lithium-ion battery negative electrode slurry;

[0080] The lithium-ion battery negative electrode slurry is coated onto copper foil using a scraper. The electrode is then placed in a vacuum oven and dried at 60°C for 12 hours. It is then cut into discs with a diameter of 12 mm to obtain the lithium-ion battery negative electrode sheet.

[0081] The obtained lithium-ion battery negative electrode sheet was used as the negative electrode, and the lithium metal sheet was used as the positive electrode. The electrolyte was a mixed system of ethylene carbonate and dimethyl carbonate containing 1 mol / L lithium hexafluorophosphate, with a volume ratio of ethylene carbonate to dimethyl carbonate of 1:1. The separator was a polypropylene membrane. The cells were assembled into coin cells in an argon-filled glove box. Finally, the cells were placed in a 25°C constant temperature chamber for electrochemical testing, with a voltage range of 0.01-2V and a capacity test at a rate of 0.5C.

[0082] like Figure 3 As shown, the battery using coffee grounds-based carbon anode material with iron powder catalysis exhibits a larger first-cycle charge-discharge capacity than the battery without iron powder catalysis. The addition of iron powder significantly increases the specific surface area of ​​the coffee grounds-based carbon anode material, thus providing more exposed redox reaction active sites and increasing electrochemical activity. Furthermore, the increased number of mesopores and micropores facilitates rapid lithium-ion insertion and extraction, thereby improving rate capability and cycle stability. In addition, the addition of iron powder lowers the temperature required to increase the degree of graphitization, achieving a relatively high degree of graphitization at 1100℃. This enhanced graphitization improves the material's conductivity, further enhancing the lithium-ion insertion and extraction capabilities.

[0083] like Figure 2 As shown, compared to coffee grounds carbon, Fe-coffee grounds carbon prepared by adding iron powder has a higher peak intensity, the peak position is shifted to the right and the characteristic peak is sharper. This indicates that the material has a higher degree of graphitization and a larger coherence length along the c-axis, and a smaller lattice spacing.

[0084] The above test results show that a coffee residue-based carbon anode material with excellent electrochemical performance, low cost and simple preparation process was synthesized by the preparation method of this application. It not only has good application prospects in lithium-ion batteries, but also has good application prospects in the field of solid-state battery anodes.

[0085] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0086] 1. Using waste coffee grounds as a carbon source, coffee grounds are an abundant byproduct of coffee production with negligible costs. By converting them into high-value-added carbon anode materials, waste can be turned into treasure, creating economic value.

[0087] 2. This preparation method uses waste coffee grounds as a precursor, which conforms to the concept of renewable environmental protection. The preparation process is simple, low in cost, and suitable for large-scale production.

[0088] 3. Under the catalytic action of iron powder, the disordered carbon skeleton of the coffee grounds precursor can undergo local graphitization and reconstruction at a relatively low temperature, forming a graphite microcrystalline network with a short-range ordered structure. This graphite microcrystalline network can improve the electronic conductivity of the material and promote the rapid diffusion of lithium ions inside the particles, thereby effectively improving the reversible specific capacity and rate performance of the material. At the same time, the iron catalysis reduces the carbonization temperature, avoiding excessive sintering and collapse of the natural pore structure of biomass during high-temperature treatment. This allows the material to retain abundant micropores and mesopores while improving conductivity, providing sufficient storage sites and transport channels for lithium ions. The coffee grounds-based carbon anode material prepared by the above method has a high specific surface area and abundant pore structure, exposing additional reaction sites and enhancing electrochemical activity. By introducing graphite microcrystals to improve conductivity, it can further improve the lithium ion insertion and extraction capabilities, thereby improving the capacity, rate performance, and cycle performance of lithium-ion batteries.

[0089] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0090] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0091] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a coffee grounds-based carbon anode material, characterized in that, include: Step S1: The coffee grounds are subjected to a first drying process to obtain coffee grounds precursor. Step S2: The coffee grounds precursor is mixed with iron powder to obtain a carbide precursor, and the carbide precursor is calcined under an inert gas atmosphere to obtain a carbonized product. Step S3 involves sequentially performing acid washing, filtration, and a second drying process on the carbonized product to obtain a coffee grounds-based anode material.

2. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of the coffee grounds precursor to the iron powder is (6:1) to (1:1).

3. The preparation method according to claim 1, characterized in that, In step S2, the calcination process is carried out under an inert gas atmosphere, the calcination temperature is 600~1300℃, and the calcination time is 1~5h.

4. The preparation method according to claim 1, characterized in that, In step S3, the inorganic acid used in the pickling treatment is hydrochloric acid or nitric acid, and the concentration of the inorganic acid is 1~3 mol / L.

5. The preparation method according to claim 1, characterized in that, In step S3, the pickling time is 46-50 hours.

6. The preparation method according to claim 1, characterized in that, In step S2, the coffee grounds precursor is mixed with iron powder to obtain a carbide precursor, comprising: The mixture of the coffee grounds precursor and the iron powder is subjected to agitation treatment; The mixture after the vibration treatment is ground to obtain the carbide precursor.

7. The preparation method according to claim 6, characterized in that, The oscillation duration of the oscillation treatment and the grinding duration of the grinding treatment are each independently 0.5~2h.

8. The preparation method according to claim 1, characterized in that, The drying temperature of the first drying treatment in step S1 and the drying temperature of the second drying treatment in step S3 are each independently 60~90℃, and the drying time of the first drying treatment in step S1 and the drying time of the second drying treatment in step S3 are each independently 10~14h.

9. A coffee grounds-based carbon anode material, characterized in that, The coffee grounds-based carbon anode material is prepared by the preparation method described in any one of claims 1-8.

10. A lithium-ion battery, comprising a positive electrode and a negative electrode, characterized in that, The negative electrode comprises the coffee grounds-based carbon negative electrode material as described in claim 9.

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