Method for recovering silicon using waste solar panels, method for manufacturing negative electrode material for secondary battery using waste solar panels, and negative electrode material for secondary battery manufactured using same

Abstract

A silicon composition according to the present invention is recovered from waste solar panels. The silicon composition is obtained through a self-propagating high-temperature synthesis method, and contains silicon and oxygen. The oxygen content in the entirety of the silicon composition is 1-7 wt%. The silicon composition may contain 0.1 wt% or less of a group including at least one among sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al).

Description

Method for recovering silicon using waste solar panels, method for manufacturing a negative electrode material for secondary batteries using waste solar panels, and a negative electrode material for secondary batteries manufactured using the same

[0001] The present invention relates to a method for recovering silicon using waste solar panels, a method for manufacturing a negative electrode material for a secondary battery using waste solar panels, and a negative electrode material for a secondary battery manufactured using the same. More specifically, the invention relates to a method for recovering silicon using waste solar panels capable of obtaining high-purity silicon, a method for manufacturing a negative electrode material for a secondary battery using waste solar panels capable of obtaining a high-performance Si-OC series negative electrode material for a secondary battery, and a negative electrode material for a secondary battery manufactured using the same.

[0002] With increasing environmental regulations and energy issues, attention is focusing on the reuse and recycling of used materials. In particular, as the volume of waste solar panels increases due to the rapid growth of the solar industry, the resource recovery of waste solar panel materials is urgent.

[0003]

[0004] There is a need for higher value-added utilization.

[0005] According to reports by the International Energy Agency and the International Renewable Energy Agency (IEA-IRENA), the cumulative amount of discarded solar panels worldwide is estimated to reach 1.7 million tons by 2030 and between 60 million and 78 million tons by 2050; consequently, technology for recycling discarded solar panels is becoming a critical issue in the solar energy sector.

[0006] Suitable recycling methods for silicon found in waste solar panels have been lacking due to insufficient purity and price competitiveness. Consequently, the absence of recycling options has led to landfill disposal, raising concerns about environmental pollution. To date, the reuse of silicon waste has been limited to solar panel recycling or the manufacture of industrial silicon powder, resulting in reduced economic and commercial viability relative to processing costs. Therefore, there is a pressing need to develop technologies for upcycling silicon from waste solar panels into high-value-added materials for secondary batteries.

[0007] Accordingly, the inventor of the present invention has completed the present invention after conducting research and going through trial and error for a long time in order to satisfy the requirement to recover silicon from the aforementioned waste solar panels and utilize it as a negative electrode material for secondary batteries.

[0008] The present invention was created to solve the problems of the prior art as described above, and one objective of the present invention is to recover high-purity silicon from waste solar panels, and high

[0009]

[0010] The present invention aims to provide a silicon composition recovered using waste solar panels, a secondary battery anode material manufactured using waste solar panels, a method for recovering the silicon composition using waste solar panels, and a method for manufacturing a secondary battery anode material using waste solar panels, wherein a secondary battery anode material can be manufactured using a material generated during the process of recovering pure silicon.

[0011] Meanwhile, other unspecified objectives of the present invention will be further considered to the extent that they can be easily inferred from the following detailed description and effects.

[0012] A silicon composition according to one aspect of the present invention is a silicon composition recovered from a waste solar panel, wherein the silicon composition is obtained through a self-propagating high-temperature synthesis method and contains silicon and oxygen, wherein the oxygen content in the entire silicon composition satisfies a compositional range of 1 wt% to 7 wt%, and the silicon composition may contain a group comprising at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al) in a compositional range of 0.1 wt% or less.

[0013] In one embodiment of the present invention, oxygen in the silicon composition is combined with silicon to form silicon oxide, and the silicon composition is formed into a powder, the powder has a size of 0.1 µm to 3.0 µm, and the size of the particles accounting for 50 v% of the powder may be less than 1 µm.

[0014] In one embodiment of the present invention, the silicon composition may have a porous structure formed by the aggregation of powder.

[0015] In one embodiment of the present invention, the self-propagating high-temperature synthesis method can obtain the silicon composition by burning pellets prepared by adding a reducing agent to crushed powder of the above-mentioned waste solar panel to obtain a combustion product, washing the combustion product with water, and sequentially proceeding with a leaching process using hydrochloric acid and a leaching process using hydrofluoric acid.

[0016] In one embodiment of the present invention, the self-propagating high-temperature synthesis method is a magnesium-based self-propagating high-temperature synthesis method, and the reducing agent may include magnesium.

[0017] In one embodiment of the present invention, the silicon composition further comprises magnesium oxide, and the weight ratio of silicon oxide to magnesium oxide may be 1:0.1 to 1:0.5.

[0018] A silicon composition according to one aspect of the present invention is a silicon composition recovered from a waste solar panel, wherein the silicon composition comprises silicon, silicon oxide, and magnesium oxide obtained through a magnesium-based self-propagating high-temperature synthesis, and wherein, throughout the silicon composition, acid

[0019] The silicon content satisfies a compositional range of 1 wt% to 7 wt%, and the weight ratio of silicon oxide to magnesium oxide is 1:0.1 to 1:0.5, and the silicon composition may include a group comprising at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al) in a compositional range of 0.1 wt% or less.

[0020] A negative electrode material for a secondary battery according to one aspect of the present invention is a negative electrode material for a secondary battery manufactured using a waste solar panel, comprising: a silicon composition obtained through a self-propagating high-temperature synthesis method and comprising silicon and oxygen; and carbon added to the silicon composition, wherein, in the entire negative electrode material for the secondary battery, silicon is included in a composition range satisfying 39% to 42 wt%, oxygen is included in a composition range satisfying 10 wt% to 13 wt%, and carbon is included in a composition range satisfying 45 wt% to 50 wt%, and the silicon composition may include a group comprising at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al) in a composition range of 0.1 wt% or less.

[0021] In one embodiment of the present invention, oxygen in the silicon composition combines with silicon to form silicon oxide, and the weight ratio of silicon to silicon oxide may be 1:0.5 to 1:0.7.

[0022] A method for recovering silicon using waste solar panels according to one aspect of the present invention comprises: a waste solar panel crushing step of crushing waste solar panels to produce crushed powder; a pellet manufacturing step of adding a reducing agent to the crushed powder and molding it to produce pellets; and a self-propagating high-temperature synthesis step of obtaining a silicon composition by a self-propagating high-temperature synthesis method using the pellets, wherein the self-propagating high-temperature synthesis step may include: a pellet combustion step of burning the pellets to obtain a combustion product; a washing step of washing the combustion product with water to obtain a first composition; a first acid injection step of adding hydrochloric acid to the first composition to obtain a second composition; and a second acid injection step of adding hydrofluoric acid to the second composition to obtain the silicon composition.

[0023] In one embodiment of the present invention, the ground powder comprises 70 wt% to 75 wt% silicon oxide (SiO2), 5 wt% to 11 wt% calcium oxide (CaO), and 10 wt% to 12 wt% sodium oxide (Na2O), and in the pellet manufacturing step, the weight ratio of the ground powder to the reducing agent is 1:0.5 to 1:2.0, and the silicon composition may comprise a group comprising at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al) in a compositional range of 0.1 wt% or less.

[0024] A method for manufacturing a negative electrode material for a secondary battery using a waste solar panel according to one aspect of the present invention comprises: a waste solar panel crushing step of crushing a waste solar panel to produce a crushed powder; a pellet manufacturing step of adding a reducing agent to the crushed powder and molding it to produce a pellet; a self-propagating high-temperature synthesis step of obtaining a silicon composition by a self-propagating high-temperature synthesis method using the pellet; and a carbon addition step of adding carbon to the silicon composition to produce a negative electrode material for a secondary battery, wherein the self-propagating high-temperature synthesis step may include a pellet combustion step of burning the pellet to obtain a combustion product; a washing step of washing the combustion product with water to obtain a first composition; and a first acid addition step of adding hydrochloric acid to the first composition to obtain the silicon composition.

[0025] In one embodiment of the present invention, the ground powder comprises 70 wt% to 75 wt% silicon oxide (SiO2), 5 wt% to 11 wt% calcium oxide (CaO), and 10 wt% to 12 wt% sodium oxide (Na2O), and in the pellet manufacturing step, the weight ratio of the ground powder to the reducing agent is 1:0.875 to 1:1.0, and the silicon composition may comprise a group comprising at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al) in a compositional range of 0.1 wt% or less.

[0026] The silicon composition recovered using waste solar panels according to the present invention, and the method for recovering the silicon composition using waste solar panels, can obtain a silicon composition containing silicon in a high content from waste solar panels.

[0027] In addition, the negative electrode material for a secondary battery manufactured using waste solar panels according to the present invention and the method for manufacturing the negative electrode material for a secondary battery using waste solar panels can manufacture a Si-OC series negative electrode material for a secondary battery by using a material from the intermediate process of recovering a silicon composition containing silicon in a high content.

[0028] FIG. 1 is a drawing illustrating a method for recovering silicon using waste solar panels according to one embodiment of the present invention.

[0029] FIG. 2 is a drawing illustrating a method for manufacturing a negative electrode material for a secondary battery using a waste solar panel according to one embodiment of the present invention.

[0030] Figure 3 is a diagram illustrating the SEM image and composition of the ground powder. Figure 4 is a diagram illustrating the EDX analysis of the ground powder.

[0031] Figure 5 is a diagram illustrating the adiabatic combustion temperature and phase equilibrium of pellets prepared by mixing crushed powder and magnesium.

[0032] Figure 6 is a diagram illustrating the temperature-time profile measured in the combustion wave of pellets prepared by mixing crushed powder and magnesium.

[0033] Figure 7 is an SEM image illustrating the microstructure of sodium silicate extracted from the solution recovered after washing.

[0034] Figure 8 is a diagram illustrating the composition of sodium silicate extracted from the solution recovered after washing.

[0035] Figures 9 and 12 are SEM images of the second composition.

[0036] FIGS. 10 and FIGS. 13 are drawings for illustrating the EDX analysis of the second composition. FIGS. 11 is a drawing for illustrating the composition of the second composition.

[0037] Figure 14 is an SEM image of the acquired high-purity silicon.

[0038] Figure 15 is a figure illustrating the EDX analysis results and composition of the acquired high-purity silicon.

[0039] It is noodles.

[0040] Figure 16 is a diagram showing SEM images of the acquired high-purity silicon at different magnifications, EDX mapping results, a photograph of the silicon composition powder, and the composition.

[0041] Figure 17 is a diagram illustrating the temperature-time profile for a Si-OC system.

[0042] all.

[0043] Figure 18 is a diagram illustrating the SEM / EDX mapping analysis results and composition of a Si-OC system.

[0044] It should be noted that the attached drawings are provided as examples for reference to help understand the technical concept of the present invention, and the scope of the rights of the present invention is not limited by them.

[0045] The terms used in this invention have been selected as widely used general terms as possible, but in specific cases, there are terms arbitrarily selected by the applicant. In such cases, the meaning should be understood by considering the meaning described or used in the specific details for implementing the invention, rather than just the name of the term.

[0046] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and not one or more

[0047]

[0048] It should be understood that the existence or possibility of addition of other features, numbers, steps, actions, components, parts, or combinations thereof is not excluded in advance.

[0049] The objects, specific advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments. Furthermore, in describing the present invention, detailed descriptions of related prior art are omitted where it is determined that such detailed descriptions may unnecessarily obscure the essence of the invention.

[0050] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0051] In the following, a silicon composition recovered from a waste solar panel and a negative electrode material for a secondary battery manufactured using a waste solar panel are described according to one embodiment of the present invention.

[0052] First, a silicon composition recovered from a waste solar panel according to one embodiment of the present invention can be obtained through self-propagating high-temperature synthesis (SHS).

[0053] The silicon composition recovered from waste solar panels may contain silicon and oxygen. In the entire silicon composition, the oxygen content may satisfy a compositional range of 1 wt% or more and 7 wt% or less. Preferably, in the entire silicon composition, the oxygen content may be 1 wt% or more and 5 wt% or less. More preferably, in the entire silicon composition, the oxygen content may be 1 wt% or more and 3.5 wt% or less. If the oxygen content in the silicon composition is 7 wt% or less, it may be immediately commercialized as high-purity silicon. Therefore, the silicon composition recovered from waste solar panels according to one embodiment of the present invention may be highly advantageous for commercialization.

[0054] In addition, since the silicon composition recovered from waste solar panels is manufactured using waste solar panels, in addition to silicon and oxygen, it may contain a minute amount of a group including at least one of calcium (Ca), magnesium (Mg), aluminum (Al), and sodium (Na). For example, the silicon composition may contain a trace amount of 0.1 wt% or less of a group including at least one of calcium (Ca), magnesium (Mg), aluminum (Al), and sodium (Na).

[0055] Oxygen in the silicon composition can combine with silicon to form silicon oxide. That is, the silicon composition may include silicon and silicon oxide. Here, silicon oxide can be represented as SiOx, where x can be 1 or 2.

[0056] In particular, given that high-purity silicon requires separate management of oxidation levels for each process, the silicon composition recovered from waste solar panels according to one embodiment of the present invention has its oxygen content controlled in the form of silicon oxide. Therefore, the oxygen content included in the silicon composition recovered from waste solar panels according to one embodiment of the present invention in the form of silicon oxide has very practical significance.

[0057] In addition, the silicon composition recovered from waste solar panels is formed into a powder, and the powder has a size of 0.1 µm to 3.0 µm, and the particle size of which accounts for 50 µm of the powder may be less than 1 µm. In addition, the silicon composition recovered from waste solar panels may have a porous structure formed by the aggregation of the powder.

[0058] The aforementioned self-propagating high-temperature synthesis method is a synthesis technique in which, once ignited, the combustion reaction proceeds spontaneously, generating high temperatures to produce products. In this method, chemical reactions between reactants proceed very rapidly, generating a large amount of heat. This generated heat is transferred to adjacent reactants, triggering new reactions, and this process continues in a chain reaction, allowing the reaction to propagate to all reactants.

[0059] In one embodiment of the present invention, the self-propagating high-temperature synthesis method can synthesize a silicon composition by burning pellets prepared by adding a reducing agent to crushed powder of waste solar panels to obtain combustion products, washing the combustion products with water, and sequentially proceeding with a leaching process using hydrochloric acid and a leaching process using hydrofluoric acid. Here, the self-propagating high-temperature synthesis method may be a magnesium-based self-propagating high-temperature synthesis method. That is, the reducing agent used in the magnesium-based self-propagating high-temperature synthesis method may include magnesium.

[0060] The silicon composition obtained through a magnesium-based self-radiating high-temperature synthesis method may further contain a trace amount of magnesium oxide. Here, the weight ratio of silicon oxide to magnesium oxide may be 1:0.1 to 1:0.5.

[0061] A small amount of magnesium oxide (MgO) is expected to play an auxiliary role in the formation of a porous structure. That is, when porous silicon is produced after the SHS process, MgO can help maintain inter-particle spacing or form pores. This strengthens the porous structure, which can improve charge and discharge performance when, for example, the silicon composition according to one embodiment is used as a negative electrode material for a lithium-ion battery.

[0062] In addition, trace amounts of magnesium oxide (MgO) are expected to improve structural stability. That is, if some MgO remains after the SHS reaction, it can play a role in improving thermal stability and mechanical strength when using the silicon composition according to one embodiment. For example, it can act as a reinforcing agent or refractory material to help prevent the porous silicon structure from collapsing at high temperatures.

[0063] For example, when the silicon oxide content in the silicon composition is 2.17 wt%, the magnesium oxide (MgO) may be 1.02 wt%. Or, when the silicon oxide content in the silicon composition is 3.14 wt%, the magnesium oxide (MgO) may be 0.32 wt%.

[0064] A negative electrode material for a secondary battery manufactured using a waste solar panel according to one embodiment of the present invention may comprise a silicon composition obtained through self-propagating high-temperature synthesis and carbon added to the silicon composition. Here, the silicon composition may comprise silicon and oxygen.

[0065] In the entire negative electrode material for a secondary battery, silicon may be included in an amount of 39% to 42 wt%, oxygen in an amount of 10 wt% to 13 wt%, and carbon in an amount of 45 wt% to 50 wt%.

[0066] Oxygen in the silicon composition can combine with silicon to form silicon oxide. Additionally, the weight ratio of silicon to silicon oxide may be 1:0.5 to 1:0.7.

[0067] In one embodiment of the present invention, the self-propagating high-temperature synthesis method can synthesize a silicon composition including silicon and silicon oxide by burning pellets prepared by adding a reducing agent to crushed powder of waste solar panels, obtaining combustion products, washing the combustion products with water, and carrying out a leaching process using hydrochloric acid.

[0068] Here, the self-radiating high-temperature synthesis method may be a magnesium-based self-radiating high-temperature synthesis method. That is, the reducing agent used in the magnesium-based self-radiating high-temperature synthesis method may include magnesium.

[0069] The negative electrode material for a secondary battery manufactured using waste solar panels may further include a trace amount of magnesium oxide. Here, the weight ratio of silicon oxide to magnesium oxide may be 1:0.1 to 1:0.5.

[0070] In the following, with reference to the attached drawings, a method for recovering silicon using waste solar panels according to one embodiment of the present invention and a method for manufacturing a negative electrode material for a secondary battery using waste solar panels are described.

[0071] FIG. 1 is a diagram illustrating a method for recovering silicon using waste solar panels according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a method for manufacturing a negative electrode material for a secondary battery using waste solar panels according to an embodiment of the present invention. FIG. 3 is a diagram illustrating an SEM image and composition of crushed powder. FIG. 4 is a diagram illustrating an EDX analysis of crushed powder. FIG. 5 is a diagram illustrating the adiabatic combustion temperature and phase equilibrium of a pellet prepared by mixing crushed powder and magnesium. FIG. 6 is a diagram illustrating the temperature-time profile measured in the combustion wave of a pellet prepared by mixing crushed powder and magnesium. FIG. 7 is an SEM image illustrating the microstructure of sodium silicate extracted from a solution recovered after washing. FIG. 8 is a diagram illustrating the composition of sodium silicate extracted from a solution recovered after washing. FIG. 9 and FIG. 12 are SEM images of the second composition. FIG. 10 and FIG. 13 are diagrams illustrating an EDX analysis of the second composition. Fig. 11 is a diagram illustrating the composition of the second composition. Fig. 14 is an SEM image of the acquired high-purity silicon. Fig. 15 is a diagram illustrating the EDX analysis results and composition of the acquired high-purity silicon. Fig. 16 is a diagram showing SEM photographs of the acquired high-purity silicon at different magnifications, EDX mapping results, photographs of the silicon composition powder, and the composition. Fig. 17 is a diagram illustrating the temperature-time profile for the Si-OC system. Fig. 18 is a diagram illustrating the SEM / EDX mapping analysis results and composition of the Si-OC system.

[0072] Referring to FIGS. 1 to 18, a method for recovering silicon using waste solar panels according to one embodiment of the present invention may include a waste solar panel recovery step (S100), a waste solar panel crushing step (S200), a pellet manufacturing step (S300), and a self-propagating high-temperature synthesis step. Here, the self-propagating high-temperature synthesis step may include a pellet combustion step (S400), a washing step (S500), a first acid injection step (S600), and a second acid injection step (S700).

[0073] Each step is explained in detail below in sequential order.

[0074] In the waste solar panel recovery step (S100), waste solar panels that have reached the end of their service life or are broken can be recovered. The waste solar panels can be recovered from the solar modules. For example, the waste solar panels can be recovered by physically separating and removing the frame, junction box, and cables of the solar modules.

[0075] In addition, glass, back sheets, and EVA (Ethylene Vinyl Acetate) attached to waste solar panels can be separated. In this process, waste solar panel glass, which is the main raw material intended by the present invention, can be obtained. For convenience of explanation, the waste solar panel glass, which is the main raw material obtained through step (S100), will be simply referred to as waste solar panels; however, it should be noted that the present invention is not limited to this term.

[0076] As described above, the recovered waste solar panels may be pre-crushed. The pre-crushing of the waste solar panels is intended to improve the crushing efficiency in the subsequent waste solar panel crushing step (S200) and to prevent the inflow of unnecessary components.

[0077] After recovering the waste solar panels, a waste solar panel crushing step (S200) can be performed.

[0078] In the waste solar panel crushing step (S200), waste solar panels can be crushed to obtain crushed powder.

[0079] The crushing of waste solar panels can be carried out using an atrition mill device. An atrition mill device is a device that crushes by friction, shearing, etc., between two discs that rotate at high speed in the same direction, and there are types in which one side of the disc is fixed and the two discs rotate in opposite directions.

[0080] The crushed powder obtained by crushing waste solar panels using an attraction mill device can have a size of about 50 mm or less.

[0081] Additionally, the ground powder may contain oxides of calcium (Ca), sodium (Na), and silicon (Si). For example, the ground powder may contain 70 wt% to 75 wt% silicon oxide (SiO2), 5 wt% to 11 wt% calcium oxide (CaO), and 10 wt% to 12 wt% sodium oxide (Na2O), and other materials. Accordingly, the ground powder according to one embodiment can be expressed as CaNaSiOx.

[0082] In particular, the ground powder obtained by grinding 150g of coarsely ground combustion product for 30 minutes using an attraction mill device that uses 600g of balls and rotates at 500rpm may have characteristics as shown in FIGS. 3 and 4. As shown in FIGS. 3 and 4, the ground powder may contain 40wt% to 45wt% oxygen, 35wt% to 40wt% silicon, 9wt% to 11wt% sodium, 1.0wt% to 2.0wt% magnesium, and 7.0wt% to 7.5wt% calcium.

[0083] In one embodiment of the present invention, the size of the pulverized powder particles may influence the control of the particle size and porous structure of the silicon composition obtained through a subsequent self-propagating high-temperature synthesis step. For example, the smaller the size of the powder particles, the smaller the particle size of the silicon composition can be controlled, and the pore size of the porous structure can be controlled uniformly. However, as the particle size of the silicon composition becomes smaller as the size of the powder particles decreases, additional silicon oxide may be generated during the synthesis of the silicon composition.

[0084] For example, it has been confirmed that when the powder particle size D50 ≤ 5 µm, the silicon particles of the obtained silicon composition have a size of 1.0 µm to 2.0 µm, whereas when the powder particle size D50 ≤ 800 nm, the silicon particles of the obtained silicon composition have a size of 0.1 µm to 1.0 µm. Therefore, proceeding with the self-propagating high-temperature synthesis process after milling the powder particles to a smaller size is certainly advantageous in terms of silicon particle control. Here, D50 means that the size of 50 v% of the particles is smaller than that size. That is, if D50 is 3 µm, the size of the powder particles accounting for 50 v% of the powder particles can be 3 µm or less.

[0085] However, it should be noted that in this case, as the smaller the powder particle size, the higher the possibility of additional oxidation of the silicon composition, and thus the oxygen content of the obtained silicon composition may be relatively higher.

[0086] According to one embodiment, the size of the powder particles is 3 µm. <D50≤6um일 때 제1 조건으로 설정한다. 그리고, 분말 입자의 크기를 600nm≤D50≤3um일 때 제2 조건으로 설정한다.

[0087] In this case, when obtaining a silicon composition under the first condition, although it is somewhat disadvantageous in terms of silicon particle control, the purity increases as the proportion of silicon oxide in the obtained silicon composition decreases as the possibility of additional oxidation is eliminated.

[0088] Conversely, while obtaining a silicon composition under the second condition is advantageous in terms of silicon particle control, the proportion of silicon oxide in the obtained silicon composition increases as the possibility of additional oxidation increases.

[0089] After crushing the waste solar panels, a pellet manufacturing step (S300) can be performed.

[0090] In the pellet manufacturing step (S300), magnesium (Mg) can be added to the crushed powder and molded to produce pellets. Here, magnesium has strong reducing power and reacts with oxides of other metals to reduce the other metals, while it itself can be oxidized. That is, magnesium can act as a reducing agent capable of reducing the metal components contained in the crushed powder during subsequent combustion.

[0091] The ratio of crushed powder to magnesium included in the pellet may be 1:0.5 to 1:2.0. The manufactured pellet may have a diameter of 4 cm to 6 cm.

[0092] After preparing pellets by mixing crushed powder and magnesium, a self-propagating high-temperature synthesis step can be performed.

[0093] The self-propagating high-temperature synthesis step may include a pellet combustion step (S400), a washing step (S500), a first acid injection step (S600), and a second acid injection step (S700).

[0094] In the pellet combustion step (S400), a combustion product can be obtained by burning a pellet containing crushed powder and magnesium.

[0095] A reaction such as the following chemical formula 1 can proceed by the combustion of the pellet described above.

[0096]

[0097] That is, the combustion products obtained by the combustion of pellets may include silicon (Si), silicon oxide (SiOx), calcium oxide (CaO), magnesium oxide (MgO), and sodium silicate (Na2SiO3).

[0098] Here, the combustion of the pellets can be carried out using an adiabatic combustion system in an argon (Ar) environment of 1.0 MPa to 1.5 MPa.

[0099] In the range where the ratio of ground powder to magnesium is 1:0.5 to 1:2.0, the adiabatic combustion temperature can be stably maintained at 1500 to 1600 degrees Celsius. Here, the ratio of ground powder to magnesium is calculated assuming that all ground powder is SiO2.

[0100] Meanwhile, as shown in FIGS. 5 and 6, it can be seen from the temperature profile that the combustion time is 5 to 15 seconds. Additionally, it can be seen that the change in combustion temperature (Tc) occurs between 1000 and 1500 in the range where the ratio (k) of the crushed powder to magnesium is 1:0.75 to 1:2.0.

[0101] As shown in Fig. 5, the combustion temperature (Tc) can be relatively low compared to the adiabatic temperature (Tad).

[0102] The difference between the adiabatic temperature (Tad) and the combustion temperature (Tc) decreases as the ratio of ground powder to magnesium (k) increases, and when the ratio of ground powder to magnesium (k) is 1.8, the adiabatic temperature (Tad) and the combustion temperature (Tc) can be the same.

[0103] After obtaining combustion products by burning pellets, a washing step (S500) can be performed.

[0104] In the washing step (S500), the combustion product can be washed with water to obtain the first composition. As the combustion product is washed with water, a reaction such as Chemical Formula 2 below can proceed.

[0105]

[0106] Some of the calcium hydroxide contained in the combustion products can be dissolved in the water used for washing. Therefore, a solution in which calcium hydroxide is dissolved in water becomes alkaline, and since sodium silicate in the combustion products dissolves in a basic solution, it can be removed by washing. That is, when the combustion products of the pellets are washed with water, the pH of the water washed by calcium hydroxide (Ca(OH)2) increases to 10, and sodium silicate dissolves in the alkaline solution and can be removed.

[0107] When the washing solution is heated after washing, water evaporates and a solid residue can be obtained. The obtained solid residue may contain sodium silicate as shown in FIGS. 7 and FIGS. 8.

[0108] Accordingly, the first composition obtained in the washing step (S500) described above may include silicon, silicon oxide, residual calcium hydroxide (Ca(OH)2) and magnesium oxide (MgO).

[0109] After obtaining the first composition by performing washing, the first acid injection step (S600) can be performed.

[0110] In the first acid injection step (S600), hydrochloric acid can be injected into the first composition after washing is completed to obtain the second composition.

[0111] As hydrochloric acid is added, a reaction such as the following chemical formula 3 can proceed.

[0112]

[0113] Magnesium oxide and calcium hydroxide in the first composition react with hydrochloric acid to be converted into magnesium chloride and calcium chloride, and some of the silicon may be oxidized to form silicon oxide. Here, if the liquid component in which magnesium chloride and calcium chloride are dissolved is removed, a second composition containing silicon and silicon oxide can be obtained as a solid component.

[0114] That is, magnesium oxide and calcium oxide in the first composition can be removed to obtain a second composition containing silicon and silicon oxide.

[0115] Meanwhile, due to the strong reducing power of magnesium, magnesium oxide is not removed by hydrochloric acid, and a very small amount of magnesium oxide may remain in the second composition.

[0116] In addition, the content of silicon oxide included in the second composition may vary depending on the amount of magnesium added during pellet manufacturing.

[0117] For example, as shown in FIGS. 9 to 11, depending on the amount of magnesium added during pellet manufacturing, the second composition may contain silicon oxide in an amount of several wt% to 15 wt% together with silicon. In particular, when the ratio of ground powder to magnesium is 1:1.4, a second composition containing silicon at the highest concentration can be obtained.

[0118] Additionally, as shown in FIGS. 12 and 13, when the ratio of ground powder to magnesium is 1:0.875 to 1:1.0, the second composition may include 70 wt% of silicon oxide together with silicon.

[0119] After obtaining the second composition, the second acid injection step (S700) can be performed.

[0120] In the second acid addition step (S700), hydrofluoric acid (HF) is added to the second composition to obtain a silicon composition containing silicon at a high content.

[0121] As hydrofluoric acid is added, a reaction such as the following chemical formula 4 can proceed.

[0122]

[0123] That is, hydrofluoric acid can react with silicon oxide to produce hexafluorosilicic acid (H2SiF6) and water. Here, since hexafluorosilicic acid (H2SiF6) is soluble in water, removing the liquid component can yield a silicon composition containing silicon in a high content. That is, hydrofluoric acid lowers the oxygen content in the silicon composition, thereby yielding a silicon composition containing high-purity silicon.

[0124] Here, the silicon composition may consist mainly of silicon but may contain a small amount of oxygen. For example, the silicon composition may contain silicon and oxygen. Additionally, the oxygen content in the total silicon composition may satisfy a range of 1 wt% to 7 wt%, as shown in FIGS. 14 and 15. FIGS. 14 (a) to (c) correspond in order to FIGS. 15 (a) to (c), respectively, and show the component content measured at each point. It should be noted that the oxygen content in the EDX phase varies from a portion showing 0 (zero) wt% (Fig. 14(b), Fig. 15(b)) to a portion showing 1.45 wt% (Fig. 14(a), Fig. 15(a)) and a portion showing 2.05 wt% (Fig. 14(c), Fig. 15(c)), but the oxygen content in the entire silicon composition according to one embodiment can satisfy a range of 1 wt% to 7 wt%.

[0125] Meanwhile, in one embodiment of the present invention, the EDX analysis method used to measure oxygen content involves inspecting the surface of a sample, which may lead to an overestimation of the surface oxidized portion of Si, potentially resulting in an overestimation of the actual oxygen content. In contrast, it should be noted that in the case of an oxygen analysis method that detects oxygen by melting the sample, the oxygen content can be measured more accurately in terms of quantity compared to the EDX analysis method described above.

[0126] In addition, since the silicon composition is manufactured using waste solar panels, it may contain a very small amount of a group including at least one of calcium (Ca), magnesium (Mg), aluminum (Al), and sodium (Na). For example, the silicon composition may contain 0.1 wt% or less of a group including at least one of calcium (Ca), magnesium (Mg), aluminum (Al), and sodium (Na).

[0127] In addition, the obtained silicon composition may be formed as a powder as shown in FIGS. 14 and 15, and may have a porous structure formed by the aggregation of the powder. Here, the powder has a size of 0.1 µm to 3.0 µm, and the size of the particles accounting for 50 v% of the powder may be less than 1 µm.

[0128] In one embodiment of the present invention, the obtained silicon composition may further include a trace amount of magnesium oxide. Here, the weight ratio of silicon oxide to magnesium oxide in the silicon composition may be 1:0.1 to 1:0.5.

[0129] Magnesium oxide can affect the porous structure of a silicon composition. For example, magnesium oxide can promote pore formation in a silicon composition and control the size and distribution of the pores.

[0130] Magnesium oxide can be dispersed within a silicon composition and serve to increase the surface area of ​​the silicon composition. Therefore, when a silicon composition containing magnesium oxide is applied to a negative electrode material for a secondary battery, the characteristics of the negative electrode for the secondary battery can be improved.

[0131] Magnesium oxide can improve the mechanical strength of silicon compositions having a porous structure. This is because magnesium oxide increases strength by hindering crack propagation within the silicon composition.

[0132] Magnesium oxide has a high melting point, so it can maintain stable properties at high temperatures. Therefore, a silicon composition containing magnesium oxide can maintain stable properties at high temperatures. Thus, when a silicon composition containing magnesium oxide is applied to a negative electrode material for a secondary battery, the high-temperature stability of the secondary battery can be improved.

[0133] As described above, a silicon recovery method using waste solar panels according to one embodiment of the present invention can produce pellets by adding magnesium to crushed powder of waste solar panels, and after burning the pellets, obtain a silicon composition containing silicon with a high content through washing with water, adding hydrochloric acid, and adding hydrofluoric acid.

[0134] Referring to FIG. 16, SEM images at different magnifications of high-purity silicon obtained according to one embodiment (Fig. 16(a), left image X13,000, right image X15,000), EDX mapping results (Fig. 16(b), left image O mapping results, right image Si mapping results), a photograph of the silicon composition powder (Fig. 16(c)), and the composition (Fig. 16(d)) are shown. As shown in the figure, a silicon composition having an oxygen content of 3.17 wt% in the entire silicon composition can be obtained.

[0135] The following describes a method for manufacturing a negative electrode material for a secondary battery using a waste solar panel according to one embodiment of the present invention.

[0136] A method for manufacturing a negative electrode material for a secondary battery using a waste solar panel according to one embodiment of the present invention may include a waste solar panel recovery step (S100), a waste solar panel crushing step (S200), a pellet manufacturing step (S300), a self-radiating high-temperature synthesis step, and a carbon addition step (S800). Here, the self-radiating high-temperature synthesis step may include a pellet combustion step (S400), a washing step (S500), and a first acid injection step (S600).

[0137] That is, the method for manufacturing a negative electrode material for a secondary battery using a waste solar panel utilizes a second composition obtained in the first acid injection step (S600) of the silicon recovery method using a waste solar panel according to one embodiment of the present invention described above, wherein the second composition obtained in the first acid injection step (S600) is a silicon composition, and may include a carbon addition step (S800) for adding carbon to the silicon composition.

[0138] However, the ratio of crushed powder and magnesium included in the pellet may be 1:0.875 to 1:1.0.

[0139] A ratio of crushed powder to magnesium of 1:0.875 to 1:1.0 is burned, the combustion product is washed to obtain a first composition, and hydrochloric acid is added to obtain a second composition, after which a carbon addition step (S800) can be performed.

[0140] In the carbon addition step (S800), a negative electrode material for a secondary battery can be manufactured by adding carbon to a second composition containing silicon and silicon oxide.

[0141] A negative electrode material for a secondary battery can be manufactured by adding a carbon-based material to high-purity silicon. That is, the negative electrode material for a secondary battery may be a Si-OC series negative electrode material for a secondary battery including silicon (Si), silicon oxide (SiOx), and silicon carbide (SiC).

[0142] Here, the negative electrode material for a secondary battery may comprise 39 wt% to 42 wt% silicon, 10 wt% to 13 wt% oxygen, and 45 wt% to 50 wt% carbon.

[0143] In particular, if carbon is added to a second composition obtained using pellets with a ratio of 1:1.0 between the ground powder and magnesium in a range of 1:0.25 to 1:0.5 between the ground powder and carbon, a Si-OC series negative electrode material for a secondary battery as shown in FIGS. 17 and 18 can be obtained.

[0144] As described above, a method for manufacturing a negative electrode material for a secondary battery using a waste solar panel according to one embodiment of the present invention can be manufactured by adding magnesium to a crushed powder of a waste solar panel to produce pellets, burning the pellets, washing with water, and adding hydrochloric acid to obtain silicon and silicon oxide, and adding carbon to the obtained silicon and silicon oxide to produce a negative electrode material for a secondary battery. Such a negative electrode material for a secondary battery may be a Si-OC series negative electrode material for a secondary battery.

[0145] Si-OC series anode materials for secondary batteries have a higher energy capacity per unit weight compared to graphite-based anode materials and can have a high charging speed. For example, the SiOx capacity obtained according to one embodiment can have a performance of 1,500 mAh / g or more based on a lithium half-cell and a 1.0 M LiPF6 EC / DMC electrolyte.

[0146] [Example]

[0147] Example 1

[0148] Waste solar panels were crushed using an attraction mill device with a ball weight of 600g and a speed of 500rpm to obtain crushed powder. Here, the size of the crushed powder was 50mm or less.

[0149] Pellet was prepared by adding 210g of magnesium (Mg) to 150g of ground powder.

[0150] Then, the pellets were adiabatically combusted at a temperature of 1500 degrees Celsius in an argon (Ar) environment of 1.3 MPa to obtain combustion products.

[0151] Then, the combustion products were washed with water and dried to obtain the first composition. Here, the solution recovered after washing showed a pH of 10 with calcium hydroxide.

[0152] Hydrochloric acid (HCl) was added to the first composition, and the liquid component was removed to obtain the second composition. The liquid component contained magnesium chloride (MgCl2) and calcium chloride (CaCl2).

[0153] Hydrofluoric acid (HF) was added to the second composition, and the liquid component was removed to obtain high-purity silicon. The liquid component contained hexafluorosilicic acid (H2SiF6) and water.

[0154] Finally, as a result of EDX analysis of the silicon composition obtained using 150g of ground powder, approximately 48g of silicon and approximately 1g of silicon oxide were contained in the silicon composition.

[0155] The obtained silicon composition consists of powder having a size of 0.1 mm to 3.0 mm and has a porous structure formed by the aggregation of powder particles.

[0156] Example 2

[0157] Waste solar panels were crushed using an attraction mill device with a ball weight of 600g and a speed of 500rpm to obtain crushed powder. Here, the size of the crushed powder was 50mm or less.

[0158] Pellet was prepared by adding 50g of magnesium (Mg) to 50g of ground powder.

[0159] Then, the pellets were adiabatically combusted at a temperature of 1500 degrees Celsius in an argon (Ar) environment of 1.3 MPa to obtain combustion products.

[0160] Then, the combustion products were washed with water and dried to obtain the first composition. Here, the solution recovered after washing showed a pH of 10 with calcium hydroxide.

[0161] Hydrochloric acid (HCl) was added to the first composition, and the liquid component was removed to obtain the second composition, a silicone composition. The liquid component contained magnesium chloride (MgCl2) and calcium chloride (CaCl2).

[0162] The second composition obtained was 35g, and the second composition contained silicon and silicon oxide.

[0163] A Si-OC series negative electrode material for secondary batteries was prepared by adding 17g of carbon to a silicon composition.

[0164] As a result of EDX analysis of the Si-OC series secondary battery anode material, the Si-OC series secondary battery anode material contained 40.13 wt% silicon, 11.02 wt% oxygen, and 48.85 wt% carbon.

[0165] The present invention is not limited to the embodiments described above, and it is obvious that new embodiments may include a combination of at least two of the above embodiments or a combination of at least one of the above embodiments and known technology.

[0166] Although the present invention has been described in detail through specific embodiments, this is for the purpose of specifically describing the present invention, and the present invention is not limited thereto. It will be obvious that modifications or improvements can be made by those skilled in the art within the technical scope of the present invention.

[0167] All simple variations or modifications of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims.

Claims

1. In a silicon composition recovered from waste solar panels, The above silicon composition is obtained through self-propagating high-temperature synthesis, and Contains silicon and oxygen, In the entire silicone composition above, the oxygen content is 1 wt% to 7 wt%, and The above silicon composition comprises a group comprising at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al) in an amount of 0.1 wt% or less.

2. In Paragraph 1, Oxygen in the above silicon composition combines with silicon to form silicon oxide, and The above silicon composition is formed as a powder, and A silicon composition in which the powder has a size of 0.1 µm to 3.0 µm, and the particle size of which accounts for 50 v% of the powder is less than 1 µm.

3. In Paragraph 2, The above silicon composition is a silicon composition having a porous structure formed by the aggregation of powder.

4. In Paragraph 3, The above self-propagating high-temperature synthesis method is, A silicon composition obtained by adding a reducing agent to the crushed powder of the above-mentioned waste solar panel to produce pellets, burning the pellets to obtain a combustion product, washing the combustion product with water, and sequentially proceeding with a leaching process using hydrochloric acid and a leaching process using hydrofluoric acid to obtain the silicon composition.

5. In Paragraph 4, The above self-propagating high-temperature synthesis method is a magnesium-based self-propagating high-temperature synthesis method, and the reducing agent is a silicon composition containing magnesium.

6. In Paragraph 5, The above silicon composition further comprises magnesium oxide, and A silicon composition in which the weight ratio of silicon oxide to magnesium oxide is 1:0.1 to 1:0.

5.

7. In a silicon composition recovered from waste solar panels, The above silicon composition comprises silicon, silicon oxide, and magnesium oxide obtained through a magnesium-based self-propagating high-temperature synthesis method, and In the entire silicon composition above, the oxygen content is 1 wt% to 7 wt%, and the weight ratio of silicon oxide to magnesium oxide is 1:0.1 to 1:0.5, and The above silicon composition comprises a group comprising at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al) in an amount of 0.1 wt% or less.

8. In Paragraph 7, The above silicone composition is formed as a powder and has a porous structure formed by the aggregation of the powder, and A silicon composition having a particle size of less than 1 µm, accounting for 50 v% of the powder.

9. A negative electrode material for a secondary battery manufactured using waste solar panels, A silicon composition comprising silicon and oxygen obtained through self-propagating high-temperature synthesis; and Comprising carbon added to the above silicon composition, and in the entire negative electrode material for the secondary battery, Silicon is included in an amount of 39% to 42 wt%, and Oxygen is included in an amount of 10 wt% to 13 wt%, and carbon is included in an amount of 45 wt% to 50 wt%, and The above silicon composition is a negative electrode material for a secondary battery comprising 0.1 wt% or less of a group including at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al).

10. In Paragraph 9. Oxygen in the above silicon composition combines with silicon to form silicon oxide, and A negative electrode material for a secondary battery having a weight ratio of silicon to silicon oxide of 1:0.5 to 1:0.

7.

11. In Paragraph 10, The above self-propagating high-temperature synthesis method is, A negative electrode material for a secondary battery, wherein a reducing agent is added to the crushed powder of the above-mentioned waste solar panel to produce pellets, which are then burned to obtain a combustion product, the combustion product is washed with water, and a leaching process using hydrochloric acid is carried out to obtain a silicon composition including silicon and silicon oxide.

12. In Paragraph 11, The above-mentioned self-radiating high-temperature synthesis method is a magnesium-based self-radiating high-temperature synthesis method, and the above-mentioned reducing agent is a negative electrode material for a secondary battery containing magnesium.

13. In Paragraph 12, The above-mentioned negative electrode material for a secondary battery further comprises magnesium oxide, and A cathode material for a secondary battery having a weight ratio of silicon oxide to magnesium oxide of 1:0.1 to 1:0.

5.

14. A waste solar panel crushing step for crushing waste solar panels to produce crushed powder; A pellet manufacturing step of adding a reducing agent to the above-mentioned crushed powder and molding it to produce pellets; and It includes a self-propagating high-temperature synthesis step for obtaining a silicon composition by a self-propagating high-temperature synthesis method using the above pellet, and The above self-propagating high-temperature synthesis step A pellet combustion step for obtaining a combustion product by burning the above pellets; A washing step of obtaining a first composition by washing the combustion product with water; A first acid addition step of adding hydrochloric acid to the first composition to obtain a second composition; and A method for recovering silicon using waste solar panels, comprising a second acid injection step of injecting hydrofluoric acid into the second composition to obtain the silicon composition.

15. In Paragraph 14, The above-mentioned ground powder comprises 70 wt% to 75 wt% silicon oxide (SiO2), 5 wt% to 11 wt% calcium oxide (CaO), and 10 wt% to 12 wt% sodium oxide (Na2O), and In the above pellet manufacturing step, the weight ratio of the ground powder to the reducing agent is 1:0.5 to 1:2.0, and A method for recovering silicon using waste solar panels, wherein the silicon composition comprises 0.1 wt% or less of a group including at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al).

16. In Paragraph 15, The above reducing agent is a method for recovering silicon using waste solar panels containing magnesium.

17. A waste solar panel crushing step for crushing waste solar panels to produce crushed powder; A pellet manufacturing step of adding a reducing agent to the above-mentioned crushed powder and molding it to produce pellets; A self-propagating high-temperature synthesis step for obtaining a silicon composition by a self-propagating high-temperature synthesis method using the above pellet; and The method includes a carbon addition step for manufacturing a negative electrode material for a secondary battery by adding carbon to the above silicon composition, and The above self-propagating high-temperature synthesis step A pellet combustion step for obtaining a combustion product by burning the above pellets; A method for manufacturing a negative electrode material for a secondary battery using a waste solar panel, comprising: a washing step of washing the combustion product with water to obtain a first composition; and a first acid injection step of adding hydrochloric acid to the first composition to obtain a silicon composition.

18. In Paragraph 17, The above-mentioned ground powder comprises 70 wt% to 75 wt% silicon oxide (SiO2), 5 wt% to 11 wt% calcium oxide (CaO), and 10 wt% to 12 wt% sodium oxide (Na2O), and In the above pellet manufacturing step, the weight ratio of the ground powder to the reducing agent is 1:0.875 to 1:1.0, and A method for manufacturing a negative electrode material for a secondary battery using a waste solar panel, wherein the silicon composition comprises 0.1 wt% or less of a group including at least one of sodium (Na), calcium (Ca), magnesium (Mg), and aluminum (Al).

19. In Paragraph 18, The above reducing agent is a method for manufacturing a negative electrode material for a secondary battery using a waste solar panel containing magnesium.

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