An rgo / sn / cu2o composite material, a preparation method and application thereof

Abstract

The application discloses an rGO / Sn / Cu2O composite material and a preparation method and application thereof, wherein compared with Cu2O and Sn / Cu2O composite materials, the rGO / Sn / Cu2O composite material has improved first discharge specific capacity. This is mainly attributed to the synergistic effect of the rGO three-dimensional conductive network on the structure, so that the composite material has fast electron transmission on the electrode surface and fast ion diffusion in the electrode, thereby causing the electrode performance of the composite material to be significantly improved. In addition, the flexible graphene three-dimensional network further relieves the volume change caused by the expansion and shrinkage of nano Sn particles, promotes the stability of the structure; the added rGO buffer layer effectively adjusts the internal strain generated by the great expansion between Sn nano particles in the electrochemical process, and further improves the conductivity of Cu2O, thereby maintaining the structural integrity of the cycle electrode, and further improving the cycle stability of the Cu2O nano material.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and specifically relates to an rGO / Sn / Cu2O composite material, its preparation method, and its application. Background Technology

[0002] I. Lithium-ion battery anode materials

[0003] As the primary lithium storage medium in lithium-ion batteries, the anode material enables the insertion and extraction of lithium ions during charging and discharging. The performance of the anode material directly affects the overall performance of the lithium-ion battery. Current research on lithium-ion battery anode materials mainly focuses on carbon-based materials, silicon-based materials, tin-based materials, lithium titanate, and transition metal oxide materials. Regardless of the type of anode material, it must meet the following performance requirements for lithium-ion battery anode materials:

[0004] (1) During the lithium-ion insertion and extraction process, the potential should be low and slightly higher than that of metallic lithium to prevent the formation of lithium dendrites. The change in Gibbs free energy should be small to ensure that the lithium-ion battery can output a relatively high voltage smoothly.

[0005] (2) The material should be able to insert and extract a large number of lithium ions as much as possible, so as to enable the electrode to obtain high specific capacity and improve the battery capacity;

[0006] (3) The process of lithium ion insertion and extraction in the negative electrode substrate is reversible, does not cause significant volume change in the negative electrode substrate, and the main structure of the material remains relatively stable during the process, so that the cycle performance of the electrode material is well maintained.

[0007] (4) Possesses good electronic conductivity and Li + The diffusion coefficient allows electrons and lithium ions to diffuse rapidly in the matrix, and the electrode material has low polarization and good rate performance, enabling the battery to be charged and discharged smoothly.

[0008] (5) The material can form a high-performance SEI film with the liquid electrolyte;

[0009] (6) After the SEI film is formed on the surface, the electrode material will not react with the electrolyte and has good chemical and electrochemical stability within the voltage variation range;

[0010] (7) The materials are easy to prepare, inexpensive, abundant in sources, green and environmentally friendly, and have good environmental compatibility.

[0011] Given the above conditions, the biggest challenge in achieving higher energy and power density in lithium-ion batteries is selecting suitable anode materials. These materials should offer high capacity, facilitate lithium-ion diffusion into the anode, and possess good cycle life and no safety hazards. Much work has been done on researching high-performance and high-capacity anode materials for lithium-ion batteries, including carbon nanotubes (1100 mAh / g), carbon nanofibers (450 mAh / g), graphene (960 mAh / g), porous carbon (800-1100 mAh / g), silicon dioxide (1600 mAh / g), silicon (4200 mAh / g), germanium (1600 mAh / g), tin (994 mAh / g), and transition metal oxides (500-1000 mAh / g). Furthermore, metal sulfides, phosphides, and nitrides are also considered for anodes; in fact, they possess specific capacities exceeding 500 mAh / g. However, significant volume expansion, poor electron transport velocity, capacity decay, and low coulombic efficiency are major problems that must be overcome before they can be used as anodes. Nanostructuring the materials can improve these problems. The expected advantages of using nanotechnology in LIBs are as follows:

[0012] (1) Achieving an active material with a high surface area to volume ratio increases the number of active sites for lithium storage. This will lead to a significant increase in specific capacity. In addition, a high surface area means a large contact area with the electrolyte, allowing more lithium ions to cross the electrode / electrolyte interface.

[0013] (2) Considering that some electrochemical reactions are difficult to trigger in bulk materials, shifting the anode research to the nanoscale will eliminate these limitations (e.g., βMnO2).

[0014] (3) The reduction in the length of the lithium-ion diffusion path leads to an increase in the diffusion rate of lithium, which gives the battery a larger power density and specific capacity.

[0015] (4) Higher electron transfer rate.

[0016] II. Graphene

[0017] Graphene is one of the most common single-atom-thick two-dimensional (2D) nanomaterials with unique chemical and physical properties, making it a widely applicable and promising material. Graphene has become a popular candidate material for lithium-ion battery anodes due to its high theoretical specific capacity (744 mAh / g), large specific surface area, excellent conductivity, and superior carrier mobility. However, the large aspect ratio of graphene nanosheets results in a long lithium-ion transport path. Furthermore, the strong π-π bond stacking and van der Waals forces between graphene layers lead to a high tendency for natural aggregation. These drawbacks not only reduce the specific surface area and the number of active sites for lithium-ion storage but also degrade the rate performance of the electrode.

[0018] The aforementioned problems can be addressed by doping graphene sheets with atoms (sulfur, nitrogen, boron, etc.) or by producing different types of two-dimensional and three-dimensional porous graphene. Kwang et al. synthesized nitrogen-doped graphene with a nitrogen content of 8.1% using microwave radiation. Compared to undoped graphene, its conductivity was significantly improved, due to nitrogen doping altering the electron migration of the graphene sheets. Simultaneously, nitrogen atoms provide more functional group design for the material. The synergistic effect between doped atoms also affects the lithium storage performance of the material. Ai et al. synthesized N and S co-doped graphene with an initial discharge capacity of 1636 mAh / g, and after 500 cycles, the electrode still provided a reversible capacity of 1090 mAh / g. With increasing cycle count, the capacity of the NS-G electrode material gradually increased, which is related to the improvement of material performance by lithium ions. This is mainly due to the changes in the internal structure and charge density of graphene caused by the differences in electronegativity and size between the doped atoms and carbon atoms, thereby improving the electrochemical performance of the material.

[0019] Generally, two-dimensional porous graphene materials can be obtained by creating planar carbon vacancy defects on graphene nanosheets.

[0020] Three-dimensional porous graphene materials can be prepared through self-assembly between graphene layers. Zhao et al. used a wet chemical method to generate pores on the surface of a reduced graphene substrate, significantly improving lithium-ion transport performance. Lin et al. utilized the properties of Ag nanoparticles to oxidize graphitic carbon and adjusted the size of the Ag nanoparticles to control the size of the graphene pores. This perforated structure is suitable for lithium-ion storage. The pores are Li-containing during the lithium insertion / extraction process. +Diffusion provides shortcuts through layers, effectively enhancing the rate performance of LIBs even in the presence of re-stacking. Graphene and carbon nanotubes are better known as modifiers to alter the properties of electroactive materials. They can form effective conductive networks within the active material, increasing the number of lithium-ion diffusion pathways and improving reaction kinetics. Simultaneously, cross-linked carbon materials provide good support for the overall material, accommodating the volume expansion of the active material during cycling. Graphene is also used as a conductive additive, participating in the modification of electrode materials in a "point-oriented" conductive mode. However, its layered structure has different effects on electron and lithium-ion transfer. While the 2D planar structure can accelerate electron transfer rates, it slows down lithium-ion diffusion. This difference in flux leads to polarization, reducing the reaction driving force.

[0021] III. Research Progress of Sn Materials

[0022] In recent years, Sn-based anodes have emerged as prominent candidate materials for improving the performance of lithium-ion batteries (LIBs). Over the past few decades, researchers have explored Sn metal, SnO2, SnO, and SnS... Extensive research has been conducted on the applications of tin, resulting in several review articles. For example, Pang et al. conducted extensive research on SnS. Lee's review specifically focused on the latest advancements in LIBs using tin oxide and sulfide anodes, detailing some of the drawbacks of these materials. Furthermore, tin-based materials can be widely used in alkaline (earth) ion anode batteries, including lithium-ion, sodium-ion, potassium-ion, and magnesium-ion batteries. Currently, significant research progress has been made in tin-based anodes, particularly in novel component design and battery reaction mechanisms. Over the past few decades, research on the structural design of tin, tin oxide, and sulfide-based anodes has evolved from studying simple combinations of elements to researching complex and advanced mixtures.

[0023] IV. Sn alloy-based composite anode

[0024] In early research, the electrochemical performance of tin was typically improved by preparing tin-based alloys. During lithium insertion and extraction, Sn acts as the active material and reacts with Li. + The reaction proceeds, while the inactive material acts as a buffer matrix to buffer the volume change of Sn. The size and phase structure of the alloy particles will greatly affect the capacity and cycling stability of LIBs. Yamamoto et al. found that using submicron-sized SnSb... xAlloys can significantly improve the reversible capacity and cycling stability of LIBs. Compared with Sb, Cu has better conductivity and lower oxidation potential, which is beneficial for improving electrochemical performance. Therefore, SnCu alloys have also attracted much attention. Liu et al. reported a unique 3D nanoporous SnCu foam electrode prepared by electrodeposition. In addition, they also adjusted the composition of SnCu alloy and found that the Cu6Sn5 intermetallic compound has better rate performance due to its unique porous structure. In addition to tin-based binary alloys, a series of ternary alloys have also been developed. Sun et al. studied a novel Sn... 50 Sb 44 The Co6 anode, encapsulated in a microporous Cu substrate, exhibits both high rate performance and long cycle life. This superior electrochemical performance is primarily attributed to the synergistic effect between the novel chemical structure and the excellent conductivity provided by the Cu framework.

[0025] However, the improvement of LIB performance by tin-based alloys remains limited. Combining tin alloy anodes with carbon materials such as carbon nanotubes (CNTs) and graphene has proven to be an effective method to achieve better electrochemical performance. Pan reported a novel core-shell 3D anode composed of Sn-Ni-Cu alloy@carbon nanorod arrays. The prepared electrode exhibited excellent rate performance at a current density of 9 A / g and cycled over 400 times at a current density of 0.45 A / g. Its superior performance is attributed to the carefully designed structure, which provides robust porosity for large volume changes with the help of stable carbon nanorods and a Cu-Ni alloy framework. Besides one-dimensional carbon, two-dimensional graphene has also been used to composite with Sn alloys. Yu et al. investigated a surfactant assembly method to fabricate a novel three-dimensional structure in which Sn-Co alloy nanoparticles are encapsulated by a graphene network. Due to the unique three-dimensional cytoskeleton, highly interconnected nanopores are formed in situ, capable of accommodating large volume expansion. The graphene framework ensures that the Li... + And the rapid entry of electrons. The prepared electrode exhibits high rate performance and good cycling stability.

[0026] While the introduction of a carbon matrix can improve the structural stability of the electrode and significantly enhance its capacity retention, the particle size of tin-based alloys is generally larger than 10 nm, and as mentioned earlier, they are prone to breakage during repeated cycles. Furthermore, it is difficult to control the uniform dispersion of these alloy nanoparticles within the carbon matrix, which can lead to localized volume changes and rapid capacity decay. To address these two issues, Yu et al. proposed an inorganic-organic dual-network hydrogel strategy to immobilize ultrafine tin-iron alloys within a three-dimensional carbon framework. This Sn-Fe@C electrode exhibits high reversible capacity and an ultralong cycle life.

[0027] V. Tin / Carbon Composite Anode

[0028] The strategy of designing intricate hierarchical structures by combining pure Sn with various carbon materials has also attracted widespread attention. Depending on the carbon source, such as amorphous carbon, carbon nanotubes, and graphene, metallic tin can be combined with one or more of them. In early studies, tin nanoparticles were typically dispersed in amorphous carbon. For example, Scrosati et al. reported a nanostructured Sn-C electrode synthesized by calcination using metallic Sn as a precursor. However, the dense assembly without pores is insufficient to buffer the large volume expansion of Sn. To address this, Maier et al. designed a unique structure in which metallic tin nanoparticles are encapsulated in porous, multi-channel carbon microtubes (denoted as SPMCT) using electrospinning. This provides sufficient space to buffer the volume changes of Sn. Simultaneously, the porous carbon framework maintains structural stability and provides Li + / Electron transport channels. Similarly, a series of Sn / CNT composites, porous Sn / composite materials, and yolk-shell Sn@C nanostructures have been studied. However, tin has a low melting point (232°C) and particles aggregate during high-temperature carbonization, so producing well-dispersed ultrafine tin nanoparticles encapsulated in a carbon matrix is ​​a major challenge.

[0029] To address this issue, Wang et al. demonstrated an aerosol spray pyrolysis technique to construct a nano-tin / carbon composite material, in which uniformly dispersed 10 nm tin is encapsulated within a spherical carbon matrix. The prepared nano-Sn / C electrode exhibits a high reversible capacity of 710 mAh / g and shows no capacity decay after 130 cycles.

[0030] Studies have shown that the small particle size, uniform distribution, and porous framework of tin are all beneficial to improving the electrochemical performance of materials. However, integrating these three factors into a single system architecture remains a significant challenge. Recently, Chen et al. reported a simple one-pot synthesis method for novel tin / carbon composites, which embeds ultrafine tin particles (~5 nm) into a nitrogen-doped porous carbon matrix by carbide divalent tin complexes. This novel composite exhibits a high reversible capacity of 480 mAh / g at a high current density of 5 A / g, indicating its good rate performance.

[0031] Besides amorphous carbon and one-dimensional carbon nanotubes or nanowires, two-dimensional graphene also possesses excellent properties, such as superior electrical conductivity, good thermodynamic stability, and a large specific surface area. It is considered a promising matrix for further improving the electrochemical performance of lithium-ion batteries (LIBs). Various Sn-graphene hybrid anode structures have been developed. Wang et al. reported a method of growing Sn@CNT nanostructures on the surface of graphene. Compared with graphene / tin-based anodes, this novel tin-based nanocomposite material exhibits greater reversible capacity and superior rate performance. Although the electrochemical performance of LIBs has been improved, their rate performance and cycle life are far inferior to other tin alloys and tin-carbon composite anodes. This is mainly due to the recombination of graphene nanosheets and the non-uniform distribution of tin nanoparticles. Therefore, careful design of the tin-graphene hybrid structure is needed to avoid the aggregation of graphene nanosheets and tin nanoparticles and maintain the activity and integrity of the electrode during high-rate charge-discharge processes. To address this, Li et al. constructed a 3D porous graphene network with a graphene shell fixed on Sn nanoparticles. Due to the low packing density of graphene nanosheets, most reported Sn-graphene hybrids exhibit low volumetric capacity. To solve this problem, Guo et al. designed a nitrogen-doped carbon material encapsulated in high-density graphene. The prepared HDN-C@Sn / G composite material exhibited a volumetric capacity of 2.6 g / cm³. 3 The novel anode exhibits high density. Furthermore, nitrogen doping, carbon doping, and graphene doping provide a double coating for the uniform tin nanoparticles, effectively preventing the aggregation of tin active particles. Therefore, the novel anode demonstrates a capacity of 2692 mAh / cm³. 3 It exhibits high volumetric capacity, with no significant capacity decay after 100 cycles at 0.1 A / g.

[0032] VI. Composite anodes made of Sn / metal oxides and other materials

[0033] Tin / carbon composite anodes can effectively improve the cycle stability of lithium-ion batteries. However, the theoretical capacity of carbon materials is relatively low, which will consume the total Li-carbon content of the composite anode. + Storage capacity. Furthermore, the chemical bond between carbon and metallic tin is typically weak, further reducing the interfacial strength of the composite material. Based on these drawbacks, transition metal oxides such as SnO... xTiO2, ZnO, Fe3O4, and MnO have attracted increasing attention. Since the volume expansion of TiO2 during charge and discharge is negligible, it has been used as an ideal matrix material. Manthiram et al. prepared a 3D mesoporous TiO2-Sn / C core-shell nanowire array as the anode for LIBs. Wang et al. reported a TiO2-Sn@carbon nanofiber (TiO2-Sn@CNT) anode prepared using electrospinning and atomic layer deposition techniques. In the constructed structure, uniformly dispersed tin nanoparticles are attached to carbon nanofibers as a first coating. The outer TiO2 tubes have sufficient space to act as a protective shell for Sn to prevent pulverization. Therefore, the prepared electrode maintained a stable capacity (643 mAh / g) after 1100 cycles at a current density of 200 mAh / g. Mao et al. rationally designed a Sn-MnO@N yolk-shell structure and doped it with carbon as the anode for LIBs. Due to the synergistic effect of the nano-Sn-MnO core, robust carbon coating, heteroatom doping, and rational yolk shell 3D interconnect network, the prepared anode exhibits high specific capacity and excellent cycling stability.

[0034] Besides metal oxides, other materials such as MXenes and ceramic polymers have also been explored as effective matrices. MXenes are a novel 2D layered material that exhibits better electrochemical performance compared to traditional 2D anodes. Therefore, combining high-capacity anode materials with MXenes is considered an effective strategy. He et al. designed nanostructured Sn / SnO using an in-situ growth strategy. x @Ti3C2MXene composite material. MXene has been shown to significantly accelerate Li... + Electron migration speed is increased, thus significantly improving the rate performance of LIBs. Kovalenko et al. recently reported a novel synthetic method that can generate uniformly distributed Sn in a modified silicon carbide oxide (SiOC) matrix. Due to the high proportion of free carbon in SiOC, the SiOC / Sn hybrid material exhibits high reversible capacity, thus resulting in high rate performance. Furthermore, tin-based MOF composites have also emerged as potential anode materials for LIBs. Recently, Chen et al. synthesized a novel tin-based MOF hybrid that exhibits high cycling stability.

[0035] VII. Overview of Cu2O Properties

[0036] Cuprous oxide is a monovalent copper oxide with the molecular formula Cu₂O. It generally exists as brick-red or reddish-brown crystals and powders. Cu₂O is abundant in nature, mainly in the form of cuprite. Cu₂O is insoluble in water and organic solvents, but soluble in dilute hydrochloric acid, dilute sulfuric acid, and ammonium chloride solutions. Cu₂O is relatively stable under room temperature and dry conditions. It is only oxidized to copper oxide (CuO) after prolonged heating or in humid air. Heating Cu₂O above 2000 K will decompose it into copper and oxygen. The crystal structure of Cu₂O is body-centered cubic.

[0037] In recent years, Cu₂O has received increasing attention in academia, mainly because it is a high-performance p-type semiconductor material with advantages such as non-toxicity, ease of preparation, and good chemical stability. It possesses unique optical and magnetic properties, showing potential applications in photocatalysis and photoelectric conversion. With a band gap of approximately 2.17 eV, it can theoretically absorb visible light for photocatalysis and photoelectric conversion; its theoretical maximum photoelectric conversion efficiency can reach 18%, and many publications have reported that Cu₂O can theoretically decompose water into hydrogen and oxygen under visible light. Due to its theoretical specific capacity, Cu₂O has also seen some research progress in the fields of solar cells and lithium-ion batteries.

[0038] VIII. Research Progress of Cu2O in Lithium-ion Batteries

[0039] Due to its diverse morphologies, simple synthesis, and environmental friendliness, Cu₂O / Cu composites have attracted widespread attention as potential alternatives to LIBs. Core-shell Cu₂O / Cu composites were prepared using electrodeposition technology. Enhanced performance retention (approximately 450 mAh / g) was achieved, and a performance of 5 mA / cm² was obtained. 2 The high current density was achieved. The obtained anode material exhibited reversibility at a rate of 100 mA / g. Spherical Cu₂O, as the anode material for LIBs, possesses excellent cycle stability and reversibility. Morphology and crystallinity are important parameters determining the electrochemical performance of Cu₂O. Over the past two decades, the number of published articles on Cu₂O-based LIBs has been steadily increasing. This demonstrates the important role Cu₂O-based LIBs play in the modern energy field.

[0040] Current research indicates that Cu₂O powder and thin film materials exhibit excellent electrochemical performance as anode materials for lithium-ion batteries, demonstrating high specific capacity and good reversible cycle performance. As a lithium-ion anode material, P. Poizot et al. proposed the application of Cu₂O with Li₂O… +The reaction mechanism is as follows: During discharge, Cu2O is reduced to nano-sized Cu particles and dispersed in the Li2O matrix. During charging, it is oxidized back to Cu2O. The theoretical capacity of Cu2O is 375 mAh / g.

[0041] YH Lee et al. deposited Cu2O films on a Pt substrate using a constant current electrochemical deposition method. SEM and TEM images showed a strong bond between Cu2O and the Pt substrate. Electrochemical performance tests indicated that the Cu2O films prepared by this method exhibited high electrochemical capacity and cycle retention; after 50 cycles, the capacity remained at 220 mAh / g, with almost no capacity decay except in the first cycle. Y. Yu et al. deposited Cu₂O-Li₂O composite films on nickel foam and copper foil using electrostatic spray deposition (ESD), exhibiting a network-like porous structure. Electrochemical tests showed that, as a negative electrode material for lithium-ion batteries, the capacity of this composite film not only did not decrease with cycling but actually increased, with a capacity increase of 0.81% per cycle. Furthermore, the cycling performance of the Cu₂O-Li₂O film on the nickel foam substrate was significantly better than that of the Cu₂O-Li₂O film deposited on copper foil. At a charge-discharge current of 15C, the capacity still reached 305 mAh / g. This is likely due to the three-dimensional network-like porous structure of the nickel foam, which has a large specific surface area, resulting in good electrical contact with the active material and reducing Li₂O content. + The diffusion pathway was improved, thereby enhancing the electrochemical performance of the material. S. Bijani et al. prepared uniform and dense Cu₂O films on a Ti substrate using a constant potential electrodeposition method, with thicknesses below 1 μm and particle sizes ranging from 60 to 400 nm. The authors believe that the reversibility of the reaction is closely related to the film thickness. Since Cu₂O is a semiconductor, excessively thick films affect the electrocontact ability between Cu₂O particles and the substrate. Films with a thickness of around 300 nm exhibited very good electrochemical performance, with the capacity increasing with cycling, maintaining around 350 mAh / g after 60 cycles. In summary, Cu₂O and its composites have been extensively studied in LIBs, yielding significant results.

[0042] IX. Significance of the Research

[0043] The above analysis shows that the severe volume expansion of tin during lithiation is one of the biggest obstacles limiting its practical application. Cu₂O can also react with Li₂. +Lithium storage through displacement reactions is considered a promising anode material for lithium-ion batteries. However, its poor conductivity and significant volume changes during charge-discharge inevitably lead to pulverization and loss of electrochemical activity, resulting in rapid capacity decay and hindering its practical application. This invention addresses this issue by compositing Sn with Cu₂O and rGO, effectively mitigating the volume expansion of tin-based materials during charge-discharge while improving the conductivity of Cu₂O. The resulting composite material exhibits excellent electrochemical performance.

[0044] The severe volume changes of tin during lithiation can lead to pulverization of the overall structure, resulting in rapid capacity decay and poor cycle stability, thus limiting its application in commercial lithium-ion batteries. Surface composite modification of tin and transition metal oxides can achieve high energy density and high stability in Sn-based anode materials supported by transition metal oxides, which is of great significance and practical value for promoting the commercial development of Sn-based anodes in lithium-ion batteries. Furthermore, the self-supporting (anodic oxidation, electrochemical deposition) process for preparing electrode materials avoids the addition of conductive agents (such as carbon black) and polymer binders during powder electrode preparation, thus ensuring electronic contact between the active material and the current collector and improving the electrode's energy density. Self-supporting electrode materials exhibit better stability, are less prone to decomposition, peeling, and damage, thereby extending battery life and cycle life. Since no conductive agents or binders are needed, battery manufacturing costs can be significantly reduced. In summary, compared to traditional coating processes, the self-supporting process for preparing lithium-ion battery anode materials offers higher energy density, longer lifespan, and lower manufacturing costs, and is therefore gradually becoming a research hotspot in the battery manufacturing field. This invention aims to provide a new strategy for preparing next-generation low-cost, high-energy-density tin-based anode materials for lithium-ion batteries by studying the lithium storage performance of rGO / Sn / Cu2O composite materials. Through microstructural characterization and electrochemical performance testing of Cu2O, Sn / Cu2O, and rGO / Sn / Cu2O composite materials prepared under different conditions, the energy storage mechanism of tin-based anode materials with different components is revealed, providing guidance for the development of high-energy-density lithium-ion battery anode materials. This will further promote the development and commercialization of Sn-based anode materials in future high-performance lithium-ion batteries. Summary of the Invention

[0045] This invention provides an rGO / Sn / Cu2O composite material, its preparation method, and its application, in order to solve the problems in the prior art.

[0046] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0047] In a first aspect, a method for preparing an rGO / Sn / Cu2O composite material is provided, comprising the following steps:

[0048] Preparation of S1 and Cu2O

[0049] The anodic oxidation method for preparing nano-Cu₂O is a relatively mature process, and extensive research has been conducted both domestically and internationally. Its main principle is that an oxidation reaction occurs at the copper anode in an alkaline electrolyte, producing Cu₂O. + Meanwhile, a reduction reaction occurs at the cathode, producing OH- in the electrolyte. - Cu produced by copper anode + and OH released from the cathode - In combination, the current method for preparing nano-Cu2O by anodic oxidation mostly uses pure copper sheets as electrodes and synthesizes it in an alkaline solution. Cu2O is generated through the dissolution of anolyte copper and subsequent hydrolysis and precipitation reaction. The synthesis mechanism is as follows:

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056] In the process of preparing Cu2O by anodic oxidation, factors such as the composition and concentration of the electrolyte, electrolytic potential, reaction system temperature, pH, current density, and additives all affect the quality and morphology of the synthesized Cu2O.

[0057] Cut several copper foils with a diameter of Φ19 mm using an electrode cutter, place them in a beaker, add 10 ml of acetone and clean in an ultrasonic cleaner for 5 minutes, then add 15 ml of anhydrous ethanol and clean in an ultrasonic cleaner for 5 minutes, and finally add 50 ml of deionized water and clean in an ultrasonic cleaner for 5 minutes. Then place it in a vacuum drying oven at 40℃. Prepare an alkaline electrolyte with a NaCl concentration of 0.3 mol / L and a NaOH concentration of 5 mol / L. After preparation, seal with plastic wrap and set aside for later use. Select a two-electrode system, using the pre-treated copper foil as the working electrode and a platinum sheet as the counter electrode, with a distance of 1-4 cm between the two electrodes. Place the electrolyte beaker in a water bath, control the electrolyte temperature at 20-40℃, set a constant current of 10-30 mA, and set the time to 2-8 min. Place the prepared sample in a small beaker; clean with distilled water and anhydrous ethanol, and then place in a vacuum drying oven for later use.

[0058] Preparation of S2 and Sn / Cu2O composite materials

[0059] Cu2O with a current of 10-50 mA and an oxidation time of 3-8 min was selected as the working electrode, and a platinum electrode was used as the counter electrode. The distance between the anode and cathode was 1-4 cm. The electrolyte was a 0.1 mol / L SnCl2·2H2O alcohol solution (anhydrous ethanol). The water bath was turned on and the temperature was set to 25-50 °C. The water bath was heated for 5 minutes to make the temperature of the electrolyte in the beaker the same as the temperature of the water in the water bath. The constant current DC power supply was set to 10-30 mA and the electrochemical deposition time was set to 3-12 min. The obtained sample was placed in a small beaker, cleaned with alcohol, and then dried in a vacuum drying oven for later use.

[0060] The preparation of S3, rGO / Sn / Cu2O composite materials includes the following steps:

[0061] S31, Preparation of Graphene Oxide (GO)

[0062] GO solution was prepared using a modified Hummers method. First, 120 ml of concentrated sulfuric acid and 3 g of sodium nitrate were weighed into a flask and placed in ice water. Once the temperature dropped to approximately 0 °C, 5 g of graphite was slowly added, and the mixture was stirred for 15 min. Then, 20 g of potassium permanganate was slowly added to the flask, maintaining the solution temperature at approximately 10 °C, and the mixture was stirred for 60 min. The flask was then placed in warm water and heated to approximately 35 °C, and stirred for 30 min. Approximately 400 ml of distilled water was slowly added to the flask, with continuous stirring. During this process, the solution temperature was maintained at approximately 90 °C. Subsequently, a 5% hydrogen peroxide solution was added until no more bubbles were produced. The solution was then filtered while hot, and repeatedly washed until neutral. The product was then added to 1800 ml of distilled water, and after complete dissolution, it was centrifuged for 20 min (3000-5000 rpm) to separate the layers. The upper layer was discarded, and the lower precipitate was collected. Repeat this step until the pH of the supernatant is neutral, then stop washing. Sonicate the collected precipitate for 30 minutes (200-300W), then centrifuge. Collect the supernatant to obtain the GO solution (1.2 mg / ml).

[0063] Preparation of S32, rGO / Sn / Cu2O composite materials

[0064] The lithium storage performance of Sn / Cu2O composites under different electrochemical deposition conditions was studied, determining that the optimal current for the Sn / Cu2O composite was 10-40 mA and the optimal electrochemical deposition time was 5-10 min. Based on this, rGO was added to improve its electrochemical performance, thus preparing an rGO / Sn / Cu2O composite. A schematic diagram of the synthesis of the Cu2O / Sn / rGO composite is shown below. Figure 3 As shown. Add 5-10g of CTAB (equal mass to Sn) to 50ml of a 25% (v / v) aqueous ethanol solution and stir for 10-20min to obtain an alcoholic solution of CTAB. Under the action of the surfactant CTAB, the Sn surface becomes positively charged. Then take 1-3ml of GO solution and sonicate for 1-3h. Make the GO solution alkaline (pH>7) with 1mol / L NaOH, giving it a negative charge. Then add the GO solution to the alcoholic solution of CTAB to obtain an alcoholic GO solution. Use Sn / Cu2O as the working electrode and a platinum electrode as the counter electrode, with a cathode-cathode distance of 10-20 cm. Use the GO alcoholic solution as the electrolyte. Open the water bath, set the temperature to 40℃, and heat for 5 minutes to make the temperature of the electrolyte in the beaker the same as the temperature of the water in the water bath. Set the constant current DC power supply to 20-50 mA and the electrochemical deposition time to 5-20min. During this process, Sn and GO will undergo in-situ electrostatic self-assembly to form a GO / Sn complex. The obtained sample was placed in a small beaker and rinsed repeatedly with anhydrous ethanol 2-3 times. After drying, it was soaked in 40% (mass fraction) hydrazine hydrate for 10 min, rinsed with anhydrous ethanol 2-3 times, and then dried to obtain the rGO / Sn / Cu2O composite material. The preparation flow chart is shown below. Figure 3 As shown.

[0065] Secondly, an rGO / Sn / Cu2O composite material prepared by the above preparation method is provided.

[0066] Thirdly, an application of the rGO / Sn / Cu2O composite material prepared by the above method is provided, wherein the rGO / Sn / Cu2O composite material is used as a battery electrode.

[0067] Furthermore, the rGO / Sn / Cu2O composite material has a discharge capacity of 1264.4 mAh / g after 200 cycles; the capacity retention rate of the rGO / Sn / Cu2O composite material is 85.5% during 10 to 200 cycles.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] (1) Compared with Cu2O and Sn / Cu2O composites, the initial discharge specific capacity of rGO / Sn / Cu2O composites is improved. This is mainly attributed to the synergistic effect of the rGO three-dimensional conductive network in the structure, which enables the composite material to have rapid electron transfer on the electrode surface and rapid ion diffusion inside the electrode, thus resulting in a significant improvement in the electrode performance of the composite material. In addition, the honeycomb porosity of Cu2O increases the active sites, and the inherent energy of nano-Sn is also present; the flexible graphene three-dimensional network further alleviates the volume change caused by the expansion and contraction of nano-Sn particles, promoting structural stability.

[0070] (2) The rGO / Sn / Cu2O composite material exhibited a high discharge capacity of 1264.4 mAh / g after 200 cycles, and the capacity retention rate was 85.5% during 10~200 cycles. The above results strongly demonstrate that the added rGO buffer layer effectively modulates the internal strain caused by the huge expansion between Sn nanoparticles during electrochemical processes, and further improves the conductivity of Cu2O, thereby maintaining the structural integrity of the cycling electrode and further improving the cycling stability of Cu2O nanomaterials.

[0071] (3) The present invention employs a self-supporting (anodic oxidation, electrochemical deposition) process to prepare electrode materials, avoiding the addition of conductive agents (such as carbon black) and polymer binders during powder electrode preparation. This ensures electronic contact between the active material and the current collector, thereby improving the energy density of the electrode. Existing technologies use a coating method, while the self-supporting electrode material prepared in this invention is integral and exhibits better stability. The electrode material is less prone to decomposition, peeling, and damage, thus extending the battery's lifespan and cycle life. Since no conductive agents or binders are required, the manufacturing cost of the battery can be significantly reduced. In summary, compared to traditional coating processes, the self-supporting process for preparing lithium-ion battery anode materials offers higher energy density, longer lifespan, and lower manufacturing costs. Attached Figure Description

[0072] Figure 1 This is a schematic diagram of the synthesis of Cu2O nanofilm in this invention; Figure 2 This is a schematic diagram of the synthesis of the Sn / Cu2O composite material in this invention; Figure 3 This is a schematic diagram of the synthesis of the rGO / Sn / Cu2O composite material in this invention; Figure 4 These are the XRD patterns of rGO, Sn / Cu2O and rGO / Sn / Cu2O composite materials in this invention; Figure 5These are SEM images and EDS elemental mapping diagrams of the rGO / Sn / Cu2O composite material in this invention, wherein: (a) is the SEM image, (b) is the elemental mapping diagram, (c) is the Sn element, and (d) is the C element; Figure 6 These are the charge-discharge curves of the rGO / Sn / Cu2O composite material in this invention at 0.5C for the first, second, fifth, and tenth cycles. Figure 7 The cycling performance and coulombic efficiency of the rGO / Sn / Cu2O composite material in this invention at 0.5C; Figure 8 The rate performance of Cu2O, Sn / Cu2O and rGO / Sn / Cu2O composites in this invention at 0.5, 1.0, 2.0, 5.0 and 0.5C; Figure 9 This is the AC impedance diagram of the Cu2O, Sn / Cu2O and rGO / Sn / Cu2O composite materials in this invention. Detailed Implementation

[0073] The present invention will be further described below with reference to embodiments.

[0074] Example 1

[0075] Preparation of S1 and Cu2O

[0076] Cut several copper foils with a diameter of Φ19 mm using an electrode cutter. Place them in a beaker, add 10 ml of acetone and clean in an ultrasonic cleaner for 5 minutes, then add 15 ml of anhydrous ethanol and clean in an ultrasonic cleaner for 5 minutes, and finally add 50 ml of deionized water and clean in an ultrasonic cleaner for 5 minutes. Then place them in a vacuum drying oven at 40℃. Prepare an alkaline electrolyte with a NaCl concentration of 0.3 mol / L and a NaOH concentration of 5 mol / L. After preparation, seal with plastic wrap and set aside for later use. Select a two-electrode system, using the pre-treated copper foil as the working electrode and a platinum sheet as the counter electrode, with a distance of 1-4 cm between the two electrodes. Place the electrolyte beaker in a water bath, control the electrolyte temperature at 20-40℃, set a constant current of 10-30 mA, and set the time to 2-8 min. Place the prepared sample in a small beaker; clean with distilled water and anhydrous ethanol, and then place in a vacuum drying oven for later use.

[0077] Example 2

[0078] Preparation of S2 and Sn / Cu2O composite materials

[0079] Cu2O with a current of 10-50 mA and an oxidation time of 3-8 min was selected as the working electrode, and a platinum electrode was used as the counter electrode. The distance between the anode and cathode was 1-4 cm. The electrolyte was a 0.1 mol / L SnCl2·2H2O alcohol solution (anhydrous ethanol). The water bath was turned on and the temperature was set to 25-50 °C. The water bath was heated for 5 minutes to make the temperature of the electrolyte in the beaker the same as the temperature of the water in the water bath. The constant current DC power supply was set to 10-30 mA and the electrochemical deposition time was set to 3-12 min. The obtained sample was placed in a small beaker, cleaned with alcohol, and then dried in a vacuum drying oven for later use.

[0080] Example 3

[0081] Preparation of S3, rGO / Sn / Cu2O composite materials

[0082] S31, Preparation of Graphene Oxide (GO)

[0083] GO solution was prepared using a modified Hummers method. First, 120 ml of concentrated sulfuric acid and 3 g of sodium nitrate were weighed into a flask and placed in ice water. Once the temperature dropped to approximately 0 °C, 5 g of graphite was slowly added, and the mixture was stirred for 15 min. Then, 20 g of potassium permanganate was slowly added to the flask, maintaining the solution temperature at approximately 10 °C, and the mixture was stirred for 60 min. The flask was then placed in warm water and heated to approximately 35 °C, and stirred for 30 min. Approximately 400 ml of distilled water was slowly added to the flask, with continuous stirring. During this process, the solution temperature was maintained at approximately 90 °C. Subsequently, a 5% hydrogen peroxide solution was added until no more bubbles were produced. The solution was then filtered while hot, and repeatedly washed until neutral. The product was then added to 1800 ml of distilled water, and after complete dissolution, it was centrifuged for 20 min (3000-5000 rpm) to separate the layers. The upper layer was discarded, and the lower precipitate was collected. Repeat this step until the pH of the supernatant is neutral, then stop washing. Sonicate the collected precipitate for 30 minutes (200-300W), then centrifuge. Collect the supernatant to obtain the GO solution (1.2 mg / ml).

[0084] Preparation of S32, rGO / Sn / Cu2O composite materials

[0085] The lithium storage performance of Sn / Cu2O composites under different electrochemical deposition conditions was studied, determining that the optimal current for the Sn / Cu2O composite was 10-40 mA and the optimal electrochemical deposition time was 5-10 min. Based on this, rGO was added to improve its electrochemical performance, thus preparing an rGO / Sn / Cu2O composite. A schematic diagram of the synthesis of the Cu2O / Sn / rGO composite is shown below. Figure 3 As shown. Add 5-10g of CTAB (equal mass to Sn) to 50ml of a 25% (volume percentage) aqueous ethanol solution and stir for 10-20min to obtain an alcoholic solution of CTAB. Under the action of the surfactant CTAB, the Sn surface becomes positively charged. Then take 1-3ml of GO solution and sonicate for 1-3h. Make the GO solution alkaline (pH>7) with 1mol / L NaOH, making it negatively charged. Then add the GO solution to the alcoholic solution of CTAB to obtain an alcoholic GO solution. Use Sn / Cu2O as the working electrode, a platinum electrode as the counter electrode, a cathode-cathode distance of 10-20 cm, and the electrolyte as the alcoholic GO solution. Open the water bath, set the temperature to 40℃, and heat for 5 minutes to make the temperature of the electrolyte in the beaker the same as the temperature of the water in the water bath. Set the constant current DC power supply to 20-50 mA and the electrochemical deposition time to 5-20min. During this process, Sn and GO will undergo in-situ electrostatic self-assembly to form a GO / Sn complex. The obtained sample was placed in a small beaker and rinsed repeatedly with anhydrous ethanol 2-3 times. After drying, it was soaked in 40% (mass fraction) hydrazine hydrate for 10 min, rinsed with anhydrous ethanol 2-3 times, and then dried to obtain the rGO / Sn / Cu2O composite material. The preparation flow chart is shown below. Figure 3 As shown.

[0086] Structural characterization and lithium storage performance of rGO / Sn / Cu2O composite material

[0087] (1) XRD phase analysis

[0088] Figure 4 The XRD patterns of C, Sn / Cu2O and rGO / Sn / Cu2O composites are shown. The patterns of the composites mainly contain strong diffraction peaks of Cu and weak diffraction peaks of C, Sn and Cu2O. Characteristic peaks appear near 43.3º, 50.6º and 74.3º, respectively, corresponding to the (111), (200) and (220) crystal planes of Cu (PDF#04-0836). A weak diffraction peak exists near 36.5º, which, according to Cu2O (PDF#34-1354), corresponds to the (111) plane of Cu2O. In addition, diffraction peaks are present at 30.7°, 32.1° and 44.9°, corresponding to the (200) plane, (101) plane and (211) plane of Sn-PDF#04-0673, respectively. The broad peak at 26.6° corresponds to the (002) crystal plane of C (PDF#41-1487), and this diffraction peak is contributed by reduced graphene oxide. Furthermore, no other characteristic peaks of impurities are present in the nanomaterial. These results demonstrate that the rGO / Sn / Cu2O composite material was successfully synthesized using this method.

[0089] (2) SEM morphological observation

[0090] The morphology of the rGO / Sn / Cu2O composite material was observed using scanning electron microscopy, such as... Figure 5 As shown in (a). From Figure 5 As shown in (a), Sn nanoparticles and the rGO three-dimensional conductive network are simultaneously coated on the surface of Cu2O. Compared to the Sn / Cu2O composite material, the conductive bridges constructed by the rGO three-dimensional conductive network on the Cu2O nanosheet surface not only prevent the accumulation of nano-Sn particles but also further limit the volume expansion of Sn, shorten the ion transport path, and enhance electronic conductivity. This ternary interconnected structure lays the foundation for excellent electrochemical performance. The corresponding elemental energy dispersive spectroscopy (EDS) diagram is shown below. Figure 5 (bd)) characterizes the elemental distribution in the rGO / Sn / Cu2O composite material. From Figure 5 As can be clearly seen in (bd), the uniform distribution of C and Sn elements throughout the Cu2O nanosheets indicates the homogeneity of rGO / Sn / Cu2O. This analysis further confirms the successful synthesis of the rGO / Sn / Cu2O composite material.

[0091] (3) Electrochemical performance study

[0092] (3.1) Charge-discharge curves

[0093] The charge-discharge curves of the rGO / Sn / Cu2O composite material at 0.5C for the first, second, fifth, and tenth cycles are shown below. Figure 6As shown, the rGO / Sn / Cu2O composite material exhibits a discharge specific capacity of 2218.1 mAh / g and a reversible capacity of 1681.9 mAh / g during the first cycle. Compared to the Cu2O and Sn / Cu2O composite materials, the rGO / Sn / Cu2O composite material shows an improved initial discharge specific capacity. This is mainly attributed to the synergistic effect of the rGO three-dimensional conductive network in the structure, which enables rapid electron transfer on the electrode surface and rapid ion diffusion inside the electrode, resulting in a significant improvement in the electrode performance of the composite material. In addition, the flexible graphene three-dimensional network further mitigates the volume change caused by the expansion and contraction of nano-Sn particles, promoting structural stability. The initial coulombic efficiencies of Cu2O, Sn / Cu2O, and rGO / Sn / Cu2O composite materials are 71.7%, 75.8%, and 79.8%, respectively, and the fifth-cycle coulombic efficiencies are 92.7%, 94.5%, and 84.8%, respectively. Compared to the initial coulombic efficiency, the fifth-week coulombic efficiency increased by 21.0%, 10.7%, and 13.0%, respectively. This is because during the initial discharge, an unstable SEI film forms on the electrode surface, leading to electrolyte decomposition and irreversible capacity generation, resulting in low coulombic efficiency. However, with increasing cycle count, a stable SEI film gradually forms on the electrode surface, the discharge curves converge, and the coulombic efficiency improves.

[0094] (3.2) Long-cycle performance

[0095] To further compare the electrochemical performance of Cu2O, Sn / Cu2O, and rGO / Sn / Cu2O, the cycling stability of the three composite materials was tested at a current density of 0.5C. The results are as follows: Figure 7 As shown in the figure, the Cu2O and Sn / Cu2O composites maintained discharge specific capacities of 117.8 and 796.6 mAh / g, respectively, after 200 cycles at 0.5C, with capacity retention rates of 45.8% and 76.2% during the 20–200 cycle range. However, the rGO / Sn / Cu2O composite exhibited a high discharge capacity of 1264.4 mAh / g after 200 cycles, with a capacity retention rate of 85.5% during the 10–200 cycle range. These results strongly demonstrate that the added rGO buffer layer effectively modulates the internal strain caused by the large expansion between Sn nanoparticles during electrochemical processes and further improves the conductivity of Cu2O, thereby maintaining the structural integrity of the cycling electrode and further improving the cycling stability of the Cu2O nanomaterials.

[0096] (4) Regarding rate capability: Figure 8The rate performance of Cu2O, Sn / Cu2O, and rGO / Sn / Cu2O composites after 40 cycles at currents of 0.5, 1.0, 2.0, 5.0, and 0.5 C is presented. The rGO / Sn / Cu2O composite exhibits the best rate performance, with discharge specific capacities of 1391.7, 1255.5, 1069.3, 951.3, and 964.7 mAh / g at 25, 60, 100, 140, and 180 cycles, respectively. In contrast, the Cu2O composites (303.3, 128.1, 65.2, 35.9, and 103.8 mAh / g) and the Sn / Cu2O composites (1160.8, 769.3, 641.1, 595.7, and 771.3 mAh / g) exhibit lower rate performance at the same current density. The improved rate performance of the rGO / Sn / Cu2O composite material is related to its unique three-dimensional structure and the rational combination of Cu2O, Sn, and rGO. The highly conductive graphene network improves electron and ion transport and increases active sites, further providing an additional interface for lithium storage, thus enabling the rGO / Sn / Cu2O composite material to exhibit better rate performance.

[0097] (5) Regarding AC impedance: This invention uses electrochemical impedance spectroscopy (EIS) to determine the electrode kinetics of Cu2O, Sn / Cu2O, and rGO / Sn / Cu2O composite materials. The faster the kinetics, the better. Through circuit fitting, such as... Figure 9 As shown. From Figure 9 It can be observed that all curves consist of semicircles in the high-frequency range and a straight line at an angle in the low-frequency range. The diameter of the semicircle represents the charge resistance, and the angled line corresponds to the diffusion rate of lithium ions in the active material. The smaller the diameter of the semicircle and the steeper the slope of the straight line, the higher the ion diffusion rate and the faster the ion intercalation / delamination kinetics. The internal resistances of Cu2O, Sn / Cu2O, and rGO / Sn / Cu2O composites are 6.4Ω, 3.2Ω, and 2.9Ω, respectively, and the charge transfer impedances are 43.9Ω, 17.9Ω, and 9.8Ω, respectively. Compared with Cu2O and Sn / Cu2O composites, the rGO / Sn / Cu2O composite has lower internal resistance and charge transfer impedance. The smallest semicircle in the high-frequency range and the largest slope in the low-frequency range reflect the lower impedance and faster ion diffusion rate in the rGO / Sn / Cu2O composite. rGO enhances the conductivity of Cu2O nanomaterials, while the three-dimensional conductive network of rGO built on the Sn / Cu2O surface effectively reduces side reactions between Sn nanoparticles and the electrolyte, thereby improving the charge transfer kinetics of rGO / Sn / Cu2O. Simultaneously, it is beneficial for reducing Li... + The diffusion resistance, thereby realizing Li +Fast transmission.

[0098] This invention effectively alleviates the volume expansion of tin-based materials during charging and discharging while improving the conductivity of Cu2O by compositing Sn with Cu2O and rGO. The composite material exhibits excellent electrochemical performance.

[0099] This invention achieves high energy density and high stability in Sn-based anode materials supported on transition metal oxides through surface composite modification of tin and transition metal oxides. This is of great significance and practical value for promoting the commercialization of Sn-based anodes in lithium-ion batteries. Furthermore, this invention employs a self-supporting (anodic oxidation, electrochemical deposition) process to prepare the electrode material, avoiding the addition of conductive agents (such as carbon black) and polymer binders during powder electrode preparation. This ensures electron contact between the active material and the current collector, improving the electrode's energy density. While existing technologies use coating methods, the self-supporting electrode material prepared in this invention is integral and exhibits better stability. The electrode material is less prone to decomposition, peeling, and damage, thus extending battery life and cycle life. Since no conductive agents or binders are needed, the manufacturing cost of the battery can be significantly reduced.

[0100] In summary, compared to traditional coating processes, self-supporting processes for preparing lithium-ion battery anode materials offer higher energy density, longer lifespan, and lower manufacturing costs, thus gradually becoming a research hotspot in the battery manufacturing field. This invention aims to provide a new strategy for preparing next-generation low-cost, high-energy-density tin-based anode materials for lithium-ion batteries by studying the lithium storage performance of rGO / Sn / Cu2O composite materials. Through microstructural characterization and electrochemical performance testing of Cu2O, Sn / Cu2O, and rGO / Sn / Cu2O composite materials prepared under different conditions, the energy storage mechanism of tin-based anode materials with different components is revealed, providing guidance for the development of high-energy-density lithium-ion battery anode materials. This will further promote the development and commercialization of Sn-based anode materials in future high-performance lithium-ion batteries.

[0101] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an rGO / Sn / Cu2O composite material, characterized in that, Includes the following steps: Preparation of Si and Cu2O; Preparation of S2 and Sn / Cu2O composite materials; Using Cu2O as the working electrode, a platinum electrode as the counter electrode, and SnCl2·2H2O alcohol solution as the electrolyte, electrochemical deposition was performed. The resulting sample was placed in a small beaker, cleaned with alcohol, and then dried in a vacuum drying oven for later use. The preparation of S3, rGO / Sn / Cu2O composite materials includes the following steps: S31, Preparation of graphene oxide (GO): Preparation of GO solution: Concentrated sulfuric acid and sodium nitrate were placed in a flask and placed in ice water. When the temperature dropped to 0 °C, graphite was added and stirred. Potassium permanganate was added to the flask and the solution temperature was maintained at 10 °C, while stirring. The flask was heated to 35 °C and stirred. Distilled water was added to the flask and stirring was continued. During this process, the solution temperature was controlled at 90 °C. Subsequently, hydrogen peroxide solution was added until no more bubbles were generated. The solution was then filtered while hot and repeatedly washed until neutral. The product was then added to a distilled aqueous solution, fully dissolved, and centrifuged to separate the layers. The upper layer was discarded, and the lower precipitate was collected. This step was repeated until the pH of the upper layer solution was neutral, at which point washing with water was stopped. The collected precipitate was sonicated and then centrifuged. The upper layer solution was collected to obtain the GO solution. Preparation of S32, rGO / Sn / Cu2O composite materials CTAB was added to an aqueous alcohol solution and stirred to obtain an alcoholic solution of CTAB. Under the action of the surfactant CTAB, the Sn surface became positively charged. GO solution was then ultrasonically treated, and NaOH was used to make the GO solution alkaline, thus giving it a negative charge. The GO solution was then added to the alcoholic solution of CTAB. Sn / Cu₂O was selected as the working electrode, a platinum electrode as the counter electrode, and the electrolyte was an alcoholic GO solution. A water bath was opened and the temperature was set to 40 °C. Heating was performed to ensure the temperature of the electrolyte in the beaker was the same as the temperature of the water in the water bath. The constant current DC power supply was set to 20-50 mA, and the electrochemical deposition time was set to 5-20 min. During this process, Sn and GO underwent in-situ electrostatic self-assembly to form a GO / Sn complex. The obtained sample was placed in a small beaker, repeatedly rinsed, dried, and then soaked in hydrazine hydrate. After rinsing and drying, the rGO / Sn / Cu₂O composite material was obtained.

2. The method for preparing the rGO / Sn / Cu2O composite material according to claim 1, characterized in that, Step S1 includes the following steps: Place copper foil in a beaker, add acetone sequentially and clean in an ultrasonic cleaner, add anhydrous ethanol and clean in an ultrasonic cleaner, then add deionized water and clean in an ultrasonic cleaner. Place the beaker in a vacuum drying oven at 40°C. Prepare an alkaline electrolyte solution with NaCl concentration of 0.3 mol / L and NaOH concentration of 5 mol / L. Seal the solution after preparation and set aside. Select a dual-electrode system, using the pre-treated copper foil as the working electrode and a platinum sheet as the counter electrode, with a distance of 1-4 cm between the two electrodes. Place the electrolyte beaker in a water bath, controlling the electrolyte temperature at 20-40°C, setting a constant current of 10-30 mA, and a time of 2-8 min. Place the prepared sample in a small beaker. After cleaning with distilled water and anhydrous ethanol, place the sample in a vacuum drying oven for later use.

3. The method for preparing the rGO / Sn / Cu2O composite material according to claim 1, characterized in that, Step S2 includes the following steps: Select Cu2O with a current of 10-50 mA and an oxidation time of 3-8 min as the working electrode, use a platinum electrode as the counter electrode, with a cathode-cathode distance of 1-4 cm, and use a 0.1 mol / L SnCl2·2H2O alcohol solution as the electrolyte. Turn on the water bath, set the temperature to 25-50 ℃, and heat for 5 minutes to make the temperature of the electrolyte in the beaker the same as the temperature of the water in the water bath. Set the constant current DC power supply to 10-30 mA and the electrochemical deposition time to 3-12 min. Place the obtained sample in a small beaker, clean it with alcohol, and then dry it in a vacuum drying oven for later use.

4. The method for preparing the rGO / Sn / Cu2O composite material according to claim 1, characterized in that, Step S31 includes the following steps: Preparation of graphene oxide (GO) solution: First, weigh 120 ml of concentrated sulfuric acid and 3 g of sodium nitrate into a flask and place it in ice water. Once the temperature drops to 0 °C, add 5 g of graphite and stir for 15 min. Add 20 g of potassium permanganate to the flask and maintain the solution temperature at 10 °C, stirring for 60 min. Place the flask in warm water and heat it to 35 °C, stirring for 30 min. Add 400 ml of distilled water to the flask and continue stirring, maintaining the solution temperature at 90 °C throughout this process. Then, add a 5% (w / w) hydrogen peroxide solution until no more bubbles are generated. Filter the solution while hot and wash repeatedly until neutral. Add the product to 1800 ml of distilled water, dissolve completely, and centrifuge to separate the layers. Discard the upper layer and collect the lower precipitate. Repeat this process until the pH of the upper layer is neutral, then stop washing. Sonicate the collected precipitate and centrifuge. Collect the upper layer to obtain a 1.2 mg / ml GO solution.

5. The method for preparing the rGO / Sn / Cu2O composite material according to claim 1, characterized in that, Step S32 includes the following steps: Add 5-10g of CTAB to 50ml of a 25% (v / v) ethanol aqueous solution and stir for 10-20min to obtain an alcoholic solution of CTAB. Under the action of the surfactant CTAB, the Sn surface becomes positively charged. Then take 1-3ml of GO solution and sonicate for 1-3h. Make the GO solution alkaline with NaOH, giving it a negative charge. Then add the GO solution to the CTAB alcoholic solution to obtain an alcoholic GO solution. Use Sn / Cu2O as the working electrode and a platinum electrode as the counter electrode, with a cathode-cathode distance of 10-20cm. Use the GO alcoholic solution as the electrolyte. Turn on the water bath and set the temperature to 40℃. Heat for 5 minutes to make the temperature of the electrolyte in the beaker the same as the temperature of the water in the water bath. Set the constant current DC power supply to 20-50V. mA, the electrochemical deposition time is set to 5-20 min. During this process, Sn and GO will undergo in-situ electrostatic self-assembly to form GO / Sn complex. The obtained sample is placed in a small beaker, rinsed repeatedly with anhydrous ethanol 2-3 times, dried, and then soaked in 40% hydrazine hydrate for 10 min. After rinsing with anhydrous ethanol 2-3 times, it is dried to obtain rGO / Sn / Cu2O composite material.

6. The rGO / Sn / Cu2O composite material prepared by any one of the preparation methods according to claims 1-5.

7. The application of the rGO / Sn / Cu2O composite material prepared by any one of the preparation methods according to claims 1-5, characterized in that, The rGO / Sn / Cu2O composite material is used as a battery electrode.

8. The application of the rGO / Sn / Cu2O composite material prepared by the method according to claim 7, characterized in that, The rGO / Sn / Cu2O composite material has a discharge capacity of 1264.4 mAh / g after 200 cycles; the capacity retention rate of the rGO / Sn / Cu2O composite material is 85.5% during 10~200 cycles.

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