Composite porous material, use thereof, silicon-based composite material, anode and battery

Abstract

The present disclosure provides a composite porous material, its use, a silicon-based composite material, a negative electrode, and a battery, specifically relating to the technical field of secondary batteries. The composite porous material includes composite porous material particles formed by combining porous materials A and B, each having two or more different pore structures, where the distribution of porous materials A and B in the composite porous material particles is not limited, and the pore volume of porous material A is larger than the pore volume of porous material B. The composite porous material according to the present disclosure is formed by combining two materials with different pore volumes, and the pore volume of the produced composite porous material can be changed stepwise, thereby controlling the amount of material loaded in the pores and improving the material change due to the loading amount.

Description

[Technical Field]

[0001] The present disclosure relates to the field of secondary battery technology, and in particular to composite porous materials, uses thereof, silicon-based composite materials, negative electrodes, and batteries.

[0002] This disclosure claims priority to application number 2023115960582, entitled "Composite porous material, use thereof, silicon-based composite material, negative electrode and battery," filed with the State Intellectual Property Office of China on November 24, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Currently, silicon has an extremely high theoretical specific capacity (4200mAh / g) and is expected to replace graphite as a next-generation high-specific-energy anode material for lithium-ion batteries. Such anode materials can meet the current market demand for high capacity and long life for lithium-ion batteries.

[0004] However, silicon undergoes severe volume expansion and contraction during repeated lithium insertion and extraction, with the expansion reaching 300% upon complete lithium insertion. Repeated large volume changes can lead to repeated formation of solid electrolyte interfaces in the composite, resulting in reduced battery capacity and poor cycling performance. Because high-capacity silicon-based composites have a relatively high silicon content, the resulting expansion problem is also severe, affecting actual battery use.

[0005] Dispersing silicon material in a porous material to produce a silicon-based composite material reduces the size of the silicon material and can partially mitigate the expansion caused by lithium intercalation. Porous materials are materials with a mesh structure consisting of interconnected or closed pores. Many conventional porous materials have a regular pore structure, resulting in uniform performance. However, when such porous materials are used to manufacture silicon-based anode materials, the regular pore structure ensures that the silicon deposition volume is nearly uniform, resulting in synchronized volume changes during lithium intercalation and deintercalation. The resulting stress from expansion or contraction can easily impact the pore structure of the porous material, affecting its structural stability and ultimately affecting the electrochemical performance of secondary batteries. This effect is particularly pronounced when the silicon content is high. Therefore, a technical challenge currently being addressed is how to effectively mitigate the expansion stress of silicon anodes with high silicon content to achieve better cycle stability.

[0006] In view of this, the present disclosure has been proposed. Summary of the Invention

[0007] A first object of the present disclosure is to provide a composite porous material formed by combining porous materials having different pore structures.

[0008] A second object of the present disclosure is to provide a use of the composite porous material in battery anode materials, hydrogen storage materials, adsorption materials, catalyst supports, energy-saving materials, separation materials or drug loading.

[0009] A third object of the present disclosure is to provide a silicon-based composite material that is made by combining silicon-based materials with different silicon contents, in order to solve the problem that composite materials with uniform silicon content in the prior art expand excessively upon lithium insertion when the silicon content is high, and to improve the cycle stability of the silicon-based composite material.

[0010] A fourth object of the present disclosure is to provide a negative electrode.

[0011] A fifth object of the present disclosure is to provide a battery.

[0012] In order to achieve the above objectives of the present disclosure, the following technical solutions are particularly adopted.

[0013] A first aspect of the present disclosure provides a composite porous material, comprising composite porous material particles formed by combining two or more porous materials having different pore structures, the composite porous material particles comprising at least porous material A and porous material B, the distribution of porous material A and porous material B in the composite porous material particles being not limited, and the pore volume of porous material A being larger than the pore volume of porous material B.

[0014] Furthermore, the porous material A is a porous carbon material, and the porous material B is at least one of a porous carbon material, a porous metal oxide, a porous metal oxoacid salt, and a porous metal.

[0015] Preferably, the porous carbon material is at least one of a porous carbon material produced by pyrolysis and / or activation of a polymer precursor, a porous carbon material produced by pyrolysis and / or activation of a biomass precursor, and a porous carbon material produced by pyrolysis and / or activation of a fossil fuel. Examples of the porous carbon material include, but are not limited to, hard carbon, amorphous carbon, carbon black, graphite, graphene, carbon nanotubes, coconut shell charcoal, etc. Examples of the porous metal oxide include, but are not limited to, at least one of porous alumina, porous silica, and porous magnesium oxide. Examples of the porous metal include, but are not limited to, at least one of foamed nickel, porous titanium, and porous copper.

[0016] Furthermore, the mass ratio of the porous material A to the porous material B is 0.1 to 200.

[0017] Preferably, in the composite porous material particles, an AB net structure is formed in which the porous material A and the porous material B are distributed alternately, and the mass ratio of the porous material A to the porous material B is 0.1 to 10.

[0018] Alternatively, an A@B core-shell structure is formed in which the porous material B encases the porous material A, and the mass ratio of the porous material A to the porous material B is 20-200.

[0019] Alternatively, an AB@C net-like core-shell composite structure is formed in which porous material C encases an AB net-like structure in which porous material A and porous material B are alternately distributed, and the mass ratio of porous material A to porous material B is 0.1 to 10, and the mass ratio of the total mass of porous material A and porous material B to porous material C is 20 to 200.

[0020] Furthermore, the pore volume of the porous material A is 0.3 to 3.0 cm 3 / g, and the pore volume of the porous material B is 0.05 to 0.65 cm 3 / g.

[0021] Preferably, in the porous material A, the proportion of pores having a diameter smaller than 10 nm in the total volume of pores in the porous material A is 60 to 100%.

[0022] Preferably, in the porous material B, the proportion of pores having a diameter smaller than 10 nm in the total volume of pores in the porous material B is 60 to 100%.

[0023] A second aspect of the present disclosure provides a use of the composite porous material in a battery anode material, a hydrogen storage material, an adsorption material, a catalyst support, an energy-saving material, a separation material or drug loading.

[0024] A third aspect of the present disclosure provides a silicon-based composite material comprising silicon-based composite particles, the silicon-based composite particles comprising a composite porous substrate and a nanosilicon material dispersed within the pores of the porous substrate, the composite porous substrate comprising at least composition A and composition B, and correspondingly, the silicon-based composite particles comprising at least region A and region B, the region A comprising composition A of the composite porous substrate and the nanosilicon material dispersed within its pores, the region B comprising composition B of the composite porous substrate and the nanosilicon material dispersed within its pores, and the weight percent of the nanosilicon material in region A is greater than the weight percent of the nanosilicon material in region B.

[0025] Furthermore, the composite porous substrate is the composite porous material described in the first aspect of the present disclosure, and preferably, the A composition in the composite porous substrate is the porous material A, and the B composition in the composite porous substrate is the porous material B.

[0026] Furthermore, an AB net structure is formed in which the A region and the B region are alternately distributed, and the mass ratio of the A region to the B region is 0.1-10.

[0027] Alternatively, an A@B core-shell structure is formed in which the region B encases the region A, and the mass ratio of the region A to the region B is 20-200.

[0028] Alternatively, an AB@C net-like core-shell composite structure is formed in which the C region encloses an AB net-like structure in which the A region and the B region are alternately distributed, and the mass ratio of the A region to the B region is 0.1 to 10, and the mass ratio of the total mass of the A region and the B region to the C region is 20 to 200.

[0029] Furthermore, the nanosilicon material is obtained by chemical vapor deposition of a silicon-containing precursor onto the composite porous substrate at 150 to 1000°C, and preferably, the silicon-containing precursor is one or more selected from the group consisting of monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silafluorene and its derivatives.

[0030] Furthermore, the content of the nanosilicon material in the region A is 30 to 90 wt. %, and the content of the nanosilicon material in the region B is 0 to 50 wt.

[0031] Additionally, the silicon-based composite material further comprises a heteroatom X deposited within the pores of the composite porous material, wherein the heteroatom X is non-silicon.

[0032] Preferably, said heteroatom X belongs to the non-metallic elements.

[0033] Preferably, the non-metallic elements include at least one of B, N, P, O and S.

[0034] Preferably, in the silicon-based composite material, the content of the hetero atom X is 0 to 10 wt. %, and more preferably, the content of the hetero atom X is 0 to 5 wt.

[0035] Preferably, the heteroatom X in the pores of the composite porous material is obtained by chemical vapor deposition of a silicon-containing precursor and a heteroatom-containing precursor onto the composite porous substrate at 150-1000°C.

[0036] Furthermore, the specific surface area of ​​the silicon-based composite material is 0.1 to 50 m 2 / g, and the pore volume is 0.001 to 0.5 cm 3 / g, and preferably, the specific surface area of ​​the silicon-based composite material is 0.1 to 5 m 2 / g, and the pore volume is 0.001 to 0.05 cm 3 / g.

[0037] and / or the true density of the silicon-based composite material is 1.3 to 3.0 g / cm 3 The closed pore volume is 0.01 to 0.30 cm 3 / g.

[0038] and / or d of the silicon-based composite particles V,50 is 5 to 20 μm, and the span, i.e., (d V,90 -d V,10 ) / d V,50 is 0.7 to 2.0, and preferably, the median diameter d V,50 is 6 to 12 μm, and the span, i.e., (d V,90 -d V,10 ) / d V,50 is 0.7 to 1.2.

[0039] And / or, the consolidated specific surface area of ​​the silicon-based composite material is 1 to 20 times, preferably 1 to 10 times, and more preferably 1 to 5 times the specific surface area.

[0040] And / or, the silicon content in the silicon-based composite material is 10 to 90 wt.%, and preferably, the silicon content in the silicon-based composite material is 30 to 70 wt.%.

[0041] and / or further comprising a coating layer located on the surface of the silicon-based composite material, wherein the material of the coating layer is preferably at least one selected from a solid electrolyte, a conductive polymer, a carbonaceous material, a metal, an alloy, a metal oxide, a metal hydroxide, a halogen-containing compound, a nitrogen-containing compound, a phosphorus-containing compound, a boron-containing compound, and a sulfur-containing compound, and more preferably the material of the coating layer is a carbonaceous material.

[0042] A fourth aspect of the present disclosure provides a negative electrode comprising a negative electrode active material comprising the silicon-based composite material according to the third aspect of the present disclosure.

[0043] A fifth aspect of the present disclosure provides a battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode comprises a negative electrode active material comprising the silicon-based composite material according to the third aspect of the present disclosure.

[0044] The present disclosure has at least the following beneficial effects compared to the prior art:

[0045] The composite porous material according to the present disclosure is a composite of at least two materials with different pore volumes, and since the pore volumes of the produced composite porous material are different in different regions, it is possible to control other physicochemical properties of the porous material in different regions, and when used as a porous carrier, it is possible to control the amount of porous material supported in each region, thereby realizing versatile control and use of the material.

[0046] The present disclosure provides composite porous materials for use in battery anode materials, hydrogen storage materials, adsorption materials, catalyst supports, energy-saving materials, separation materials, or drug loading, thereby providing high-performance composite porous materials for the above fields, promoting the development of the above fields, and broadening the scope of application to downstream industries.

[0047] The silicon-based composite material of the present disclosure uses a composite porous material as a substrate, with pore volume and pore size controllable in each region, to form a silicon-based composite material with controllable silicon content in each region after silicon deposition. When the composite particles are used in lithium-ion batteries, the regions with different silicon content experience different expansions due to lithium intercalation, with low expansion in the low-silicon content region and buffering the high expansion due to lithium intercalation in the high-silicon content region. This reduces the internal expansion of the composite particles and improves the structural and cycling stability of the composite material. Furthermore, the differences in pore volume and pore size distribution of the composite porous material can be used to form special structures such as net-like or core-shell structures, which can then be used as a base for vapor deposition of silicon. In the composite material thus formed, regions of different silicon content can alternately form net-like structures or be wrapped around each other to form core-shell structures. These specific structures enable the formation of regions with different silicon content distributions in the composite material, and can form periodic or stepwise distributions of silicon content (i.e., different silicon contents in different regions), which further optimizes the buffering mechanism for silicon expansion due to lithium insertion and improves the structural and cycling stability of the composite material.

[0048] On the other hand, by varying the distribution ratios of micropores, mesopores, and macropores for composite porous substrates of different compositions, it is possible to vary the size distribution of silicon nanoparticles in silicon-based composite materials, which allows the formation of regions in the composite material where the silicon content and silicon nanoparticle size distribution can be controlled, thereby providing a buffering mechanism for the expansion of silicon due to lithium insertion and improving the structural stability and cycle stability of the composite material.

[0049] Furthermore, composite porous substrates obtained from different precursors have different microstructures within the bulk phase of the porous material. For example, the carbon layer structure of carbon materials contains microscopic information such as interlayer distance and degree of graphitization. For example, the combination of microstructures, such as the crystalline phase structure of porous oxides, can form special structures such as nets and core-shells, which are also important properties of composite porous substrates. Silicon-based composite materials obtained by infiltrating silicon into composite porous substrates inherit the microstructure of the composite porous substrate, and the porous substrate composition of these different microstructures plays an important role in the overall performance of the silicon-based composite material.

[0050] The battery according to the present disclosure uses a higher performance silicon-based composite material, which increases the specific capacity of the secondary battery, improves the energy density and cycle performance of the battery, and promotes the development of downstream industries. [Brief explanation of the drawings]

[0051] In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings necessary for describing the embodiments are briefly described below. The following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope. It should be understood that those skilled in the art can obtain other related drawings based on these drawings without using inventive ability.

[0052] [Figure 1] 1 is an SEM image of a composite porous material according to Example 1. [Figure 2] 1 is an SEM image of a composite porous material according to Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0053] Hereinafter, embodiments of the present disclosure will be described in detail using examples. The following examples are merely for the purpose of illustrating the present disclosure and should not be considered as limiting the scope of the present disclosure. In the examples, specific conditions are not specified, but the experiments can be carried out under conventional conditions or under conditions recommended by the manufacturer. For reagents or equipment used without specifying the manufacturer, conventional commercially available products can be used.

[0054] The range endpoints and any values ​​disclosed in this disclosure should be understood not to be limited to the exact range or value, but to include values ​​close to these ranges or values. For numerical ranges, the range endpoints, the range endpoints and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0055] A first aspect of the present disclosure provides a composite porous material. The composite porous material includes composite porous material particles, each of which is formed by combining two or more porous materials having different pore structures. The composite porous material particles include at least porous material A and porous material B, and the distribution of porous material A and porous material B in the composite porous material particles is not limited, and the pore volume of porous material A is larger than the pore volume of porous material B.

[0056] The composite porous material according to the present disclosure is formed by combining two materials with different pore volumes, and since the pore volumes of the produced composite porous material are different in different regions, it is possible to control other physicochemical properties of the porous material in different regions, and when used as a porous carrier, it is possible to control the amount of porous material supported in each region, thereby realizing versatile control and use of the material.

[0057] In the composite porous material limited by the present disclosure, the pore volume of porous material A is larger than the pore volume of porous material B. The interior of the pores of the porous material is a location for supporting a second phase (substance to be supported), and the size of the pore volume determines the amount of silicon supported. In a silicon-based composite material obtained by chemical vapor deposition of the composite porous material as a substrate for a silicon-based negative electrode material, the amount of silicon supported in porous material A is larger than the amount of silicon supported in porous material B.

[0058] In some embodiments, the porous material A is a porous carbon material, and the porous material B is at least one of a porous carbon material, a porous metal oxide, a porous metal oxoacid salt, or a porous metal.

[0059] Preferably, in some embodiments, the porous carbon material is at least one of a porous carbon material produced by pyrolysis and / or activation of a polymer precursor, a porous carbon material produced by pyrolysis and / or activation of a biomass precursor, and a porous carbon material produced by pyrolysis and / or activation of a fossil fuel, etc. In some embodiments, the porous carbon material includes, but is not limited to, hard carbon, amorphous carbon, carbon black, graphite, graphene, carbon nanotubes, coconut shell charcoal, etc.

[0060] In some embodiments, the porous metal oxide includes, but is not limited to, at least one of porous alumina, porous silica, and porous magnesium oxide. In some embodiments, the porous metal oxoacid salt includes, but is not limited to, at least one of porous lithium titanate, porous aluminum phosphate, porous lithium phosphate, porous lithium aluminum phosphate, porous lithium aluminum titanium phosphate, and the like. In some embodiments, the porous metal includes, but is not limited to, at least one of foamed nickel, porous titanium, and porous copper. In some embodiments, the porous metal oxide or porous metal oxoacid salt is derived from a metal hydroxide, metal carbonate, double metal hydroxide, multiple metal hydroxide, and the like. In some embodiments, the porous metal oxide or porous metal oxoacid salt is derived from a sol or slurry of a metal hydroxide, metal carbonate, double metal hydroxide, multiple metal hydroxide, metal phosphate, metal nitrate, and the like.

[0061] In some embodiments, the mass ratio of the porous material A to the porous material B (mass of porous material A: mass of porous material B) is 0.1 to 200. Typically, the mass ratio of the porous material A to the porous material B is, but is not limited to, 0.1, 0.5, 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 150, 180, 200, or a range consisting of any two of the above values.

[0062] Preferably, in some embodiments, the composite porous material particles form an AB net structure in which the porous material A and the porous material B are alternately distributed, and the mass ratio of the porous material A to the porous material B is 0.1 to 10.

[0063] In some embodiments, an A@B core-shell structure is formed in which the porous material B encases the porous material A, and the mass ratio of the porous material A to the porous material B is 20-200.

[0064] In some embodiments, an AB net-like structure is formed in which the porous material A and the porous material B are alternately distributed, and further, a porous material C is present that envelops the AB net-like structure, thereby forming an AB@C net-like core-shell composite structure, wherein the mass ratio of the porous material A to the porous material B is 0.1 to 10, and the mass ratio of the total mass of the porous material A and the porous material B to the porous material C is 20 to 200.

[0065] In some embodiments, the pore volume of the porous material A is 0.3 to 3.0 cm 3 / g, and the pore volume of the porous material B is 0.05 to 0.65 cm 3 / g.

[0066] The pore volume of porous material A is, for example, 0.3 cm 3 / g, 0.6cm 3 / g, 0.9cm 3 / g, 1.2cm 3 / g, 1.5cm 3 / g, 1.8cm 3 / g, 2.1cm 3 / g, 2.4cm 3 / g, 2.7cm 3 / g, 3.0cm 3 / g, or any range between the two values ​​above. The pore volume of porous material B may be, for example, 0.05 cm 3 / g, 0.1cm 3 / g, 0.15cm 3 / g, 0.2cm 3 / g, 0.25cm 3 / g, 0.3cm 3 / g, 0.35cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6m 3 / g, 0.65cm 3 / g, or a range consisting of any two of the above values.

[0067] Preferably, in some embodiments, the ratio of pores having a diameter smaller than 10 nm to the total volume of pores in the porous material A is 60 to 100%. Typically, the ratio of pores having a diameter smaller than 10 nm to the total volume of pores in the porous material A may be, for example, but not limited to, 60%, 70%, 80%, 90%, 100%, or a range consisting of any two of the above values.

[0068] Preferably, in some embodiments, the ratio of pores having a diameter smaller than 10 nm to the total volume of pores in the porous material B is 60 to 100%. Typically, the ratio of pores having a diameter smaller than 10 nm to the total volume of pores in the porous material B may be, for example, but is not limited to, 60%, 70%, 80%, 90%, 100%, or a range consisting of any two of the above values.

[0069] A second aspect of the present disclosure provides use of the composite porous material according to the first aspect of the present disclosure in a battery anode material, a hydrogen storage material, an adsorption material, a catalyst support, an energy saving material, a separation material or drug loading.

[0070] The composite porous material disclosed herein can be designed to have different pore structures and specific surface areas in different regions, allowing for control of other physicochemical properties of the porous material in different regions, thereby expanding its applications in fields such as battery materials, hydrogen storage materials, adsorption materials, catalyst supports, energy-saving materials, separation materials, and drug loading. This provides composite porous materials with improved performance for these fields, promoting the development of these fields and expanding the scope of application to downstream industries. When the composite porous material is used as a porous support, the loading amount can be controlled in each region, allowing for versatile control and use of the composite material. Typically, when the composite porous material is used as a porous substrate for a silicon-based anode material, the resulting composite material allows for control of the silicon content distribution in each region, which can mitigate expansion due to lithium insertion when the silicon-based material is used in a lithium battery, improving its structural stability and cycle stability.

[0071] Different compositions of composite porous materials may also have different pore distributions. In some embodiments, porous material A is primarily composed of mesopores, while porous material B is primarily composed of micropores, or porous material A and porous material B have different distributions of micropores, mesopores, and macropores. This provides more possibilities for versatile uses of the composite porous material.

[0072] Furthermore, composite porous materials obtained from different precursors have different microstructures within the bulk phase of the porous material. For example, the carbon layer structure of carbon materials contains microscopic information such as interlayer distance and degree of graphitization. For example, the combination of microstructures, such as the crystalline phase structure of porous oxides, can form special structures such as nets and core-shell structures, which are also important properties of composite porous materials and will lead to their wider use.

[0073] When the composite porous material of the present disclosure is used as a hydrogen storage material, the designable and different pore structures and specific surface areas in each region can enhance hydrogen storage capacity and optimize hydrogen distribution. Similarly, when the composite porous material is used as a catalyst support, the catalyst can be introduced into regions with different pore volumes in a metered manner, allowing for more precise control of reaction rates.

[0074] The energy-saving materials disclosed herein include, but are not limited to, sound-absorbing or sound-proofing materials. A composite porous material has regions with gradually or periodically varying pore volumes. When sound is incident on the surface of the composite porous material, part of the sound is reflected by the surface of the composite porous material, and part of the sound propagates through the pore structure with gradually varying pore volumes, causing the air within the pores to vibrate. Then, due to the viscosity of the air and the effect of thermal conduction, the acoustic energy is converted into thermal energy and consumed. The pore structure with gradually varying pore volumes allows sound waves to propagate repeatedly, constantly converting and dissipating energy, thereby achieving a sound-absorbing effect.

[0075] When the composite porous material according to the present disclosure is used as a separation material, by designing the distribution of pore volume for each region, it is possible to provide different storage locations for different materials to be separated, thereby significantly improving the selectivity of the separation.

[0076] When the composite porous material according to the present disclosure is used for drug loading, the pore structure can be tailored for each region, allowing the main drug and auxiliary materials to be designed to be selectively loaded into specific regions, thereby improving the operability of drug loading, facilitating binding with targeting ligands, and facilitating their action within cells.

[0077] A third aspect of the present disclosure provides a silicon-based composite material. The silicon-based composite material comprises silicon-based composite particles, which comprise a composite porous substrate and a nanosilicon material dispersed within the pores of the porous substrate. The composite porous substrate comprises at least composition A and composition B, and the silicon-based composite particles accordingly comprise at least region A and region B. Region A comprises composition A of the composite porous substrate and the nanosilicon material dispersed within its pores, and region B comprises composition B of the composite porous substrate and the nanosilicon material dispersed within its pores. The mass percentage of the nanosilicon material in region A is greater than the mass percentage of the nanosilicon material in region B.

[0078] The silicon-based composite material of the present disclosure uses a composite porous material as a substrate with region-by-region controllable pore volume and pore size, and forms a silicon-based composite material with region-by-region controllable silicon content after silicon deposition. When the composite particles are used in lithium-ion batteries, the regions with different silicon content will experience different expansions due to lithium intercalation, with the low silicon content region experiencing smaller expansions and the high silicon content region experiencing greater expansion due to lithium intercalation, thereby reducing the internal expansion of the composite particles and improving the structural and cycling stability of the composite.

[0079] Furthermore, composite porous materials of different compositions may have different pore distributions. For example, in some embodiments, composition A may be primarily mesopores, while composition B may be primarily micropores. Alternatively, a composite containing both composition A and composition B may have different distributions of micropores, mesopores, and macropores. This allows the silicon nanoparticle size distribution to be varied in the silicon-based composite material, forming regions in the composite material where the silicon content and silicon nanoparticle size can be controlled, which further provides a buffering mechanism for expansion due to lithium insertion of silicon and improves the structural stability and cycling stability of the composite material.

[0080] Furthermore, composite porous substrates obtained from different precursors have different microstructures within the bulk phase of the porous material. For example, the carbon layer structure of carbon materials contains microscopic information such as interlayer distance and degree of graphitization. For example, the combination of microstructures, such as the crystalline phase structure of porous oxides, can form unique structures such as nets and core-shells, which are also important properties of composite porous substrates. Silicon-based composite materials obtained by infiltrating silicon into composite porous substrates inherit the microstructure of the composite porous substrate, and the porous substrate composition of these different microstructures plays an important role in the overall performance of the silicon-based composite material.

[0081] In some embodiments, the silicon-based composite material according to the present disclosure is a composite porous substrate that is the composite porous material described in the first aspect of the present disclosure. Preferably, the composite porous substrate having composition A is the porous material A described in the first aspect of the present disclosure, and the composite porous substrate having composition B is the porous material B described in the first aspect of the present disclosure.

[0082] In some embodiments, in the silicon-based composite material according to the present disclosure, an AB net structure is formed in which the A region and the B region are alternately distributed, and the mass ratio of the A region to the B region is 0.1 to 10.

[0083] In some embodiments, an A@B core-shell structure is formed in which the B region envelops the A region, and the mass ratio of the A region to the B region is 20-200.

[0084] In some embodiments, an AB net-like structure is formed in which the A region and the B region are alternately distributed, and further, a C region is present that envelops the AB net-like structure, thereby forming an AB@C net-like core-shell composite structure, wherein the mass ratio of the A region to the B region is 0.1 to 10, and the mass ratio of the total mass of the A region and the B region to the C region is 20 to 200.

[0085] In some embodiments, the nanosilicon material is obtained by chemical vapor deposition of a silicon-containing precursor onto the composite porous substrate at 150-1000°C. Preferably, in some embodiments, the silicon-containing precursor is one or more selected from monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silafluorene and its derivatives. Preferably, in some embodiments, the temperature at which the silicon-containing precursor contacts the porous substrate is 200-700°C.

[0086] In some embodiments, the weight percent of the nanosilicon material in Region A is 30-90%, and the weight percent of the nanosilicon material in Region B is 0-50%. The silicon content in different regions is determined by the pore volume of the different regions in the composite porous substrate. In the present disclosure, the silicon content distribution by region is the primary means for controlling and buffering lithium-intercalation-induced expansion of nanosilicon in the composite particles.

[0087] Typically, in some embodiments, the mass percentage of nanosilicon material in region A is, for example, but not limited to, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or any ranges consisting of the two above values, and the mass percentage of nanosilicon material in region B is, for example, but not limited to, 0, 10%, 20%, 30%, 40%, 50%, or any ranges consisting of the two above values. A content of 0 means that no nanosilicon material is deposited in region B.

[0088] In some embodiments, the silicon-based composite material further comprises a heteroatom X deposited within the pores of the composite porous material, wherein the heteroatom X is non-silicon.

[0089] Preferably, in some embodiments, the heteroatom X is a non-metallic element.

[0090] Preferably, in some embodiments, the non-metallic elements include at least one of B, N, P, O and S.

[0091] Preferably, in some embodiments, the content of the hetero atom X in the silicon-based composite material is 0 to 10 wt.%, and more preferably, in some embodiments, the content of the hetero atom X is 0 to 5 wt.%.

[0092] In some embodiments, the heteroatom X in the pores of the composite porous material is preferably obtained by chemical vapor deposition of a silicon-containing precursor and a heteroatom-containing precursor onto the composite porous substrate at 150 to 1000°C. In some embodiments, the temperature at which the silicon-containing precursor and the heteroatom-containing precursor contact the porous substrate is preferably 200 to 700°C. The silicon-containing precursor is preferably one or more selected from monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silafluorene and its derivatives. The heteroatom-containing precursor is a precursor containing the heteroatom element and is injected in the form of a gas. In some embodiments, the heteroatom-containing precursor includes at least one of an oxygen-containing precursor, a carbon-containing precursor, a nitrogen-containing precursor, a phosphorus-containing precursor, a sulfur-containing precursor, and a boron-containing precursor.

[0093] The contact of the silicon-containing precursor and the heteroatom-containing precursor with the porous substrate is carried out so that the silicon-containing precursor and the heteroatom-containing precursor alternately contact with the porous substrate, or the silicon-containing precursor and the heteroatom-containing precursor simultaneously contact with the porous substrate, or the silicon-containing precursor and the mixed gas containing the silicon-containing precursor and the heteroatom-containing precursor alternately contact with the porous substrate. Preferably, the heteroatom-containing precursor is introduced intermittently during the continuous contact of the silicon-containing precursor with the porous substrate.

[0094] In some embodiments, the specific surface area of ​​the silicon-based composite material is 0.1 to 50 m 2 / g, and the pore volume is 0.001 to 0.5 cm 3 / g. In some embodiments, the specific surface area of ​​the silicon-based composite material is preferably 0.1 to 5 m 2 / g, and the pore volume is 0.001 to 0.05 cm 3 / g. If the specific surface area is too high, the side reactions of the composite material increase when used in a lithium battery, resulting in a decrease in the initial coulomb efficiency. If the specific surface area is too low, it is difficult to achieve.

[0095] In some embodiments, the silicon-based composite material has a true density of 1.3 to 3.0 g / cm 3 The closed pore volume is 0.01 to 0.30 cm 3 / g.

[0096] In this specification, the skeletal density of a material obtained by helium gas pycnometry is referred to as the material's true density. The closed pore volume is calculated by subtracting the volume of a fully dense material composed of the same elements from the skeletal volume of the composite material, and the skeletal volume of a composite material is the reciprocal of the composite's true density. The skeletal volume of a composite material consists of two parts: one part is the volume of a fully dense material composed of the same corresponding elements, and the other part is the closed pore volume. The volume of a fully dense material is the reciprocal of its true density (i.e., the theoretical density of a fully dense material composed of the same elements). This allows the closed pore volume of a composite material to be calculated. A certain amount of closed pore volume can provide a buffer space for expansion of silicon in the composite material due to lithium insertion, thereby improving the cycle stability of the composite material. However, too many closed pores can reduce the structural strength of the composite material, lower the tap density, and impair battery processability. The reduced structural strength also reduces the cycle stability of the composite material. Therefore, it is necessary to keep the true density and closed pore volume of a composite material within a certain range.

[0097] Typically, in some embodiments, the true density of the silicone-based composite material obtained in the present disclosure is, for example, 1.3 g / cm 3 , 1.5g / cm 3 , 1.8g / cm 3 , 2.0g / cm 3 , 2.5g / cm 3 , 3.0g / cm 3 or a range consisting of any two of the above values, and in some embodiments, the closed pore volume is 0.01 cm 3 / g, 0.05cm 3 / g, 0.1cm3 / g, 0.15cm 3 / g, 0.2cm 3 / g, 0.25cm 3 / g, 0.30cm 3 / g, or any range consisting of the above two values, but is not limited thereto.

[0098] In some embodiments, the d of the silicon-based composite particles V,50 is 5 to 20 μm, and the span (d V,90 -d V,10 ) / d V,50 is 0.6 to 2.0, and preferably, the median diameter d V,50 is 6 to 12 μm, and the span (d V,90 -d V,10 ) / d V,50 is 0.7-1.2. Silicon-based composites with appropriate particle size distribution characteristics can achieve better processability and electrochemical performance in lithium batteries.

[0099] In some embodiments, the compressed specific surface area of ​​the silicon-based composite material is 1 to 20 times, preferably 1 to 10 times, and more preferably 1 to 5 times the specific surface area. 2 The specific surface area is the specific surface area of ​​a material after it has been consolidated under a certain pressure. The consolidated specific surface area is used to evaluate the stability of a material's structure. The lower the consolidated specific surface area of ​​a material, the smaller the ratio of its consolidated specific surface area to its specific surface area, making it more resistant to consolidation and more compressively strong, thereby improving the mechanical stability of composite materials.

[0100] In some embodiments, the silicon content in the silicon-based composite material is 10 to 90%. Preferably, in some embodiments, the silicon content in the silicon-based composite material is 30 to 70%.

[0101] In some embodiments, the silicon-based composite material further includes a coating layer located on the surface thereof. Preferably, in some embodiments, the material of the coating layer is at least one selected from a solid electrolyte, a conductive polymer, a carbonaceous material, a metal, an alloy, a metal oxide, a metal hydroxide, a halogen-containing compound, a nitrogen-containing compound, a phosphorus-containing compound, a boron-containing compound, and a sulfur-containing compound. Preferably, in some embodiments, the material of the coating layer is a carbonaceous material.

[0102] A fourth aspect of the present disclosure provides a negative electrode comprising a negative electrode active material comprising the silicon-based composite material described in the third aspect of the present disclosure.

[0103] A fifth aspect of the present disclosure provides a battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode comprises a negative electrode active material comprising the silicon-based composite material described in the third aspect of the present disclosure.

[0104] The batteries disclosed herein utilize silicon-based composites with region-specific controllable silicon content, which allows for a relatively high silicon content and high capacity while reducing the expansion of silicon within the particles due to lithium intercalation, thereby improving the cycle stability and structural stability of secondary batteries and promoting downstream industry development.

[0105] The present disclosure will be further described below using specific examples and comparative examples. However, it should be understood that these examples are intended to explain the present disclosure in more detail and are not intended to limit the disclosure in any way. The materials used in the examples and comparative examples in this disclosure can be processed under conventional conditions or under conditions recommended by the manufacturer, unless specific conditions are specified. For reagents or equipment used without a specified manufacturer, commercially available conventional products can be used.

[0106] Example 1

[0107] This example provides a composite porous material, and the preparation process is as follows:

[0108] Sucrose and lignin were mixed in a mass ratio of 1:1, and the resulting mixture was heated from room temperature to 900°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. Then, the injection of N2 was stopped, CO2 was injected, and the mixture was held for 2 hours, after which the temperature was lowered. After crushing and classification, a composite porous material was obtained.

[0109] Example 2

[0110] This example provides a composite porous material, and the preparation process is as follows:

[0111] Sucrose was heated from room temperature to 900°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. After crushing and classification, a core carbon material was obtained. The core carbon material and asphalt were mixed in a mass ratio of 25:1, and the resulting mixture was heated from room temperature to 900°C at a rate of 2°C / min in a N2 atmosphere. The N2 injection was then stopped, CO2 was injected, and the mixture was held for 2 hours, after which the temperature was lowered. After crushing and classification, a composite porous material was obtained.

[0112] Example 3

[0113] This example provides a composite porous material, and the preparation process is as follows:

[0114] Sucrose and commercially available porous alumina were mixed in a 1:1 mass ratio. The resulting mixture was heated from room temperature to 900°C at a rate of 2°C / min in a N2 atmosphere and held at that temperature for 2 hours. The N2 injection was stopped, CO2 was injected, and the mixture was held for 2 hours, then the temperature was lowered. After crushing and classification, an alumina-sucrose-carbon composite was obtained. The alumina-sucrose composite was placed in a 0.01M HCl solution, stirred for 2 hours, filtered, washed, dried, and sintered at 400°C to obtain a composite porous material.

[0115] Example 4

[0116] This example provides a composite porous material, and the preparation process is as follows:

[0117] Sucrose and lignin were mixed in a mass ratio of 1:1, and the resulting mixture was heated from room temperature to 800°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. The resulting material was crushed and classified, then mixed with asphalt in a mass ratio of 50:1, heated to 900°C in a N2 atmosphere, held for 2 hours, and then CO2 was injected and held for 2 hours to obtain a composite porous material.

[0118] Example 5

[0119] This example provides a composite porous material, and the preparation process is as follows:

[0120] Sucrose and lignin were mixed in a mass ratio of 1:1, and the resulting mixture was heated from room temperature to 800°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours to obtain a composite porous material.

[0121] Example 6

[0122] This example provides a composite porous material, and the preparation process is as follows:

[0123] Sucrose and lignin were mixed in a 1:1 mass ratio, and the resulting mixture was pre-oxidized at 200°C. The mixture was then heated from room temperature to 900°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. CO2 was then injected, and the mixture was held at 1000°C for 3 hours to obtain a composite porous material.

[0124] Comparative Example 1

[0125] This comparative example provides sucrose charcoal, prepared as follows: Sucrose was heated from room temperature to 900°C at a rate of 2°C / min in an N2 atmosphere and held at this temperature for 2 hours. The N2 injection was stopped, CO2 was injected, and the temperature was then lowered after 2 hours of holding. After pulverization and classification, sucrose charcoal was obtained.

[0126] Comparative Example 2

[0127] This comparison provides lignin charcoal, which was prepared as follows: The lignin was heated from room temperature to 900°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. The N2 injection was stopped, CO2 was injected, and the temperature was then lowered. After holding for 2 hours, the temperature was reduced. The lignin charcoal was obtained after crushing and classification.

[0128] Comparative Example 3

[0129] For this comparison, commercially available coconut shell charcoal was provided, which had an iodine adsorption capacity of 800 mg / g and a particle size of 20 to 60 mesh.

[0130] Comparative Example 4

[0131] This comparative example provides a porous alumina similar to that used in Example 3.

[0132] Measurement example 1

[0133] For each of the composite porous materials obtained in Examples 1 to 6 and the porous materials of Comparative Examples 1 to 4, the pore volume and the mass ratio of each part in the composite porous material were measured.

[0134] In measuring the pore volume, the pore volume was calculated from the amount of adsorption at the maximum N2 adsorption partial pressure (p / p0>0.99).

[0135] The pore volumes of porous material A and porous material B in the composite porous material were obtained by calculation, and pore volumes of porous material A and porous material B that make up the structure were measured individually to obtain the pore volumes of each part of the composite porous material.

[0136] The mass ratio of each part of the composite porous material was also obtained by converting the mass of each part to be carbonized and / or activated individually.

[0137] The results obtained are shown in Table 1 below.

[0138] [Table 1]

[0139] Example 7

[0140] This example provides a silicon-based composite material, the process of which is as follows:

[0141] The composite porous material obtained in Example 1 was placed in a tubular furnace and heated in an N2 atmosphere from room temperature to 600°C at a rate of 2°C / min. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0142] Example 8

[0143] This example provides a silicon-based composite material, the process of which is as follows:

[0144] The composite porous material obtained in Example 2 was placed in a tubular furnace and heated in an N2 atmosphere from room temperature to 600°C at a rate of 2°C / min. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0145] Example 9

[0146] This example provides a silicon-based composite material, the process of which is as follows:

[0147] The composite porous material obtained in Example 3 was placed in a tubular furnace and heated in an N2 atmosphere from room temperature to 600°C at a rate of 2°C / min. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0148] Example 10

[0149] This example provides a silicon-based composite material, the process of which is as follows:

[0150] The composite porous material obtained in Example 4 was placed in a tubular furnace and heated in an N2 atmosphere from room temperature to 600°C at a rate of 2°C / min. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0151] Example 11

[0152] This example provides a silicon-based composite material, the process of which is as follows:

[0153] The composite porous material obtained in Example 5 was placed in a tubular furnace and heated in an N2 atmosphere from room temperature to 600°C at a rate of 2°C / min. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 5 hours in a 20% SiH4-N2 mixed gas atmosphere. The material was purged with N2 for 2 hours, then changed to a 10% C2H2-N2 mixed gas and maintained for 2 hours. After changing to an N2 atmosphere, the temperature was naturally lowered, crushed, and classified, and then d V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0154] Example 12

[0155] This example provides a silicon-based composite material, the process of which is as follows:

[0156] The composite porous material obtained in Example 6 was placed in a tubular furnace and heated in an N2 atmosphere from room temperature to 600°C at a rate of 2°C / min. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 50 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0157] Example 13

[0158] This example provides a silicon-based composite material, which differs from Example 7 in that the obtained silicon-based composite particles are dispersed in a 5% AlPO4 aqueous solution at a mass ratio of 1:5 between the silicon-based composite material and AlPO4. After ultrasonic stirring and filtering off excess liquid, the mixture is dried in an oven at 80°C and then sintered in a N2 atmosphere at 400°C for 2 hours to obtain an AlPO4-coated silicon-based composite material.

[0159] Example 14

[0160] The composite porous material obtained in Example 1 was placed in a tubular furnace and heated in an N2 atmosphere from room temperature to 600°C at a rate of 2°C / min. The atmosphere was then changed to a 20% SiH4-N2 mixed gas, and the mixture was maintained at 600°C for 30 hours in a 20% SiH4-0.01% O2-N2 mixed gas atmosphere. After changing to the N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0161] Comparative Example 5

[0162] The porous material provided in Comparative Example 1 was placed in a tubular furnace and heated from room temperature to 600°C at a rate of 2°C / min in an N2 atmosphere. The atmosphere was then changed to a 20% SiH4-N2 mixed gas, and the mixture was maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to the N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0163] Comparative Example 6

[0164] The porous material provided in Comparative Example 2 was placed in a tubular furnace and heated from room temperature to 600°C at a rate of 2°C / min in an N2 atmosphere. The atmosphere was then changed to a 20% SiH4-N2 mixed gas, and the mixture was maintained at 600°C for 20 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0165] Comparative Example 7

[0166] The porous material provided in Comparative Example 3 was placed in a tubular furnace and heated from room temperature to 600°C at a rate of 2°C / min in an N2 atmosphere. The atmosphere was then changed to a 20% SiH4-N2 mixed gas, and the mixture was maintained at 600°C for 25 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0167] Comparative Example 8

[0168] The porous material provided in Comparative Example 4 was placed in a tubular furnace and heated from room temperature to 600°C at a rate of 2°C / min in an N2 atmosphere. The atmosphere was then changed to a 20% SiH4-N2 mixed gas, and the mixture was maintained at 600°C for 15 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was naturally lowered, and the material was crushed and classified. V,50 A silicon-based composite material with a diameter of 10 μm and a span of 0.88 was obtained.

[0169] Measurement example 2

[0170] Data on silicon deposition in the silicon-based composite materials obtained in Examples 7 to 14 and Comparative Examples 5 to 8 were measured, and the obtained data are shown in Table 2 below.

[0171] [Table 2]

[0172] Measurement example 3

[0173] The silicon-based composite materials obtained in Examples 7 to 14 and Comparative Examples 5 to 8 were subjected to electrical performance measurements.

[0174] The silicon-based composite materials obtained in Examples 7 to 14 and Comparative Examples 5 to 8 were used as negative electrode active materials to produce negative electrode sheets, and CR 2032 button batteries were produced using the negative electrode sheets in a conventional manner, and the electrical performance of the batteries was measured.

[0175] The specific measurement method is as follows.

[0176] (1) Half-cell assembly

[0177] A CR 2032 button battery was assembled in a glove box, with a metallic lithium sheet as the counter electrode and a polypropylene microporous membrane as the separator. The electrolyte consisted of LiPF6 dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio EC:DEC = 1:1), where the concentration of LiPF6 was 1 mol / L.

[0178] Battery charge and discharge measurements were performed using the LAND battery measurement system.

[0179] (2) Capacity per gram and initial efficiency measurements

[0180] After leaving the CR 2032 button cell stationary for 6 hours, it was discharged at 0.05 C to 0.005 V, then further discharged at 0.01 C to 0.005 V, left stationary for 5 minutes, and then charged at a constant current of 0.05 C to 1.5 V. The capacity per gram of initial lithium desorption is the capacity per gram (or mass specific capacity) of the electrode material, and the ratio of the capacity in the initial lithium desorption stage to the capacity in the initial lithium insertion stage is the initial coulombic efficiency of the battery.

[0181] (3) Measurement of electrode sheet expansion rate

[0182] After leaving the CR 2032 button battery stationary for 6 hours, it was discharged at 0.05C to 0.005V, and then further discharged at 0.01C to 0.005V. The button battery was then disassembled in a glove box, the electrode sheet was cleaned with DEC, and the thickness of the electrode sheet was measured. The expansion rate was calculated as follows: (electrode sheet thickness in the initial fully lithium-loaded state - new electrode sheet thickness) / new electrode sheet thickness x 100%. The new electrode sheet was the electrode sheet measured above.

[0183] Full cell fabrication and electrochemical performance measurements

[0184] The silicon-based composite materials obtained in Examples 7 to 14 and Comparative Examples 5 to 8 were used as negative electrode active materials, and pouch batteries were manufactured using an electrode sheet containing the negative electrode active materials in a conventional manner, and electrical performance measurements were performed. The pouch batteries were manufactured in a dehumidified room with a dew point temperature of -45°C. The charge / discharge cycle measurements of the batteries were performed using a LANBTS battery measurement system, and the results are shown in Table 3. The specific measurement method is as follows.

[0185] (1) Preparation of the positive electrode sheet

[0186] The positive electrode active material LiCoO2, conductive agent Super P, binder PVDF, and solvent NMP were mixed uniformly in a mass ratio of 92:3:5:150 by stirring, and then the mixture was uniformly applied to a positive electrode current collector and dried at 80°C to obtain a positive electrode sheet.

[0187] (2) Preparation of negative electrode sheet

[0188] The negative electrode active material, the conductive agent SuperP, the binder (i.e., polyacrylic acid), and the solvent (i.e., deionized water) were mixed uniformly in a mass ratio of 95:1:4:120, and then the mixture was uniformly applied to the negative electrode current collector and dried at 100°C to obtain a negative electrode sheet.

[0189] (3) The positive and negative electrode sheets were stacked in a rectangular shape and separated using a polypropylene separator to form a battery cell, which was then enclosed in an aluminum plastic bag. An electrolyte solution appropriate for the capacity of the bag was then injected into the bag, which was then vacuum sealed to form a pouch battery. The electrolyte solution was a mixture of LiPF6, EC, and DEC, where the LiPF6 concentration was 1 mol / L and the volume ratio of EC to DEC was 1:1.

[0190] (4) Chemical composition and volume classification (volume classification, performance screening and grading)

[0191] The injected and sealed batteries were then subjected to anodization. After standing in a thermostatic chamber at 25°C for 12 hours, they were charged to 3.3 V at a constant current of 0.02 C, left for 30 minutes, charged to 3.8 V at a constant current of 0.025 C, left for 10 minutes, and then charged to 4.2 V at a constant current of 0.33 C. After anodization, the batteries were evacuated, the sealing bag was sheared, and the batteries were then divided. They were charged to 4.45 V at a constant current of 0.33 C, left for 10 minutes, discharged to 3 V at a constant current of 1 C, left for 10 minutes, and then discharged to 3 V at a constant current of 0.33 C. The initial coulombic efficiency of the pouch battery was determined by dividing the discharge capacity by the charge capacity.

[0192] (5) Cycle measurement at 25°C

[0193] The battery was placed in a thermostatic chamber at 25°C and charged at a constant current of 1 C to 4.45 V, then further charged at a constant voltage of 4.45 V until the current reached 0.1 C. After allowing the battery to stand for 10 minutes, it was discharged at a constant current of 1 C to 3.0 V, allowed to stand for 10 minutes, and the above charge and discharge cycles were repeated until the discharge capacity was less than 80% of the first-cycle discharge capacity. The cycle life of the pouch battery was determined by the number of cycles. The capacity retention at 100 cycles was recorded.

[0194] The data obtained is shown in Table 3.

[0195] [Table 3]

[0196] In Examples 1 to 6, different combinations of precursors were used to obtain composite porous materials with different structures and different pore volumes in each region, such as an AB net structure, an A@B core-shell structure, and an AB@C net core-shell composite structure. Comparative Examples 1 and 2 were produced using a single carbon source precursor to produce porous materials with a single pore volume, while Comparative Examples 3 and 4 were commercially available porous materials with a single composition and pore volume.

[0197] In Comparative Examples 5 to 8, silicon-based composite materials were produced using as porous substrates the porous materials of Comparative Examples 1 to 4. In Examples 7 to 14, silicon was deposited using as composite porous substrates the composite porous materials with different pore volumes in each region obtained in Examples 1 to 6, to produce silicon-based composite materials.

[0198] As can be seen from Tables 1, 2, and 3, the silicon-based composite materials of Examples 7 to 14 have lower electrode sheet expansion rates and 100-cycle capacity retention rates than the silicon-based composite materials produced using porous materials with a single pore volume in Comparative Examples 5 to 8. The silicon-based composite materials of Comparative Examples 5 to 8 all had 100-cycle capacity retention rates of 92% or less, while the silicon-based composite materials of Examples 7 to 14 all had 100-cycle capacity retention rates of 97% or more. The exception is Example 12, in which silicon was deposited using the composite porous material of Example 6, which has a high pore volume, as the porous substrate. Therefore, the composite material has a relatively high silicon content (62.4%), achieving a 1.5V capacity per gram of 2320 mAh / g. While its 100-cycle capacity retention rate was relatively low at 94.5%, it was still higher than that of the comparative examples. Because the composite porous material used in Example 11 had a low pore volume, the silicon content of the resulting silicon-based composite material was low, resulting in a low capacity per gram.

[0199] Examples 7 to 12 employed the composite porous materials of Examples 1 to 6 as the composite porous substrate, respectively. Examples 13 and 14 both employed the composite porous material of Example 1 as the composite porous substrate. Unlike Example 7, Example 13 coated the silicon-based composite material with an inorganic electrolyte, further improving the 100-cycle capacity retention. Example 14 introduced oxoheteroatoms during silicon deposition to form Si-O-Si or SiOx localized regions in the silicon-based composite material. This resulted in strong Si-O bonds that restricted expansion of silicon due to lithium insertion, further reducing the electrode sheet expansion rate of the material and improving the cycle stability of the silicon-based composite material, resulting in a 100-cycle capacity retention of 99.2%.

[0200] Measurement example 4

[0201] The composite porous material of Example 1 was scanned using a scanning electron microscope to obtain the SEM photograph shown in Figure 1. As can be seen from Figure 1, two different pore structure regions are distributed in the composite porous material. The sparse porous regions in the upper left and lower right of the photograph are porous material A, and the dense region between them is porous material B. Due to limitations in SEM resolution, it is not possible to observe micropores in the composite porous material. However, according to common knowledge in the technical field, both porous material A and porous material B in the composite porous material of Example 1 contain micropores. On a larger scale of observation, it was found that porous material A and porous material B were distributed alternately, forming an AB net-like structure.

[0202] The composite porous material of Example 2 was scanned with a scanning electron microscope to obtain the SEM photograph shown in Figure 2. Figure 2 shows that the densification of the interior and outer shell of the composite porous material was different, forming an A@B core-shell structure.

[0203] Finally, it should be noted that the above embodiments are merely for illustrating the technical solutions of the present invention, and are not intended to limit the same. Although the above embodiments are used to describe the present invention in detail, those skilled in the art may modify the technical solutions described in the above embodiments or make equivalent substitutions for some or all of the technical features therein. Such modifications or substitutions do not deviate from the essence of the technical solutions and the scope of the technical solutions according to the embodiments of the present invention. [Industrial Applicability]

[0204] The composite porous material of the present disclosure can be used in fields such as battery anode materials, hydrogen storage materials, adsorption materials, catalyst supports, energy-saving materials, separation materials, or drug loading, providing high-performance composite porous materials for the above fields, promoting the development of the above fields, and expanding the scope of application to downstream industries.

Claims

1. Composite porous material particles comprising two or more porous materials having different pore structures, The composite porous material particles contain at least a porous material A and a porous material B, and the distribution of the porous material A and the porous material B in the composite porous material particles is not limited; The pore volume of the porous material A is larger than the pore volume of the porous material B; A composite porous material characterized by:

2. the porous material A is a porous carbon material, and the porous material B is at least one of a porous carbon material, a porous metal oxide, a porous metal oxoacid salt, or a porous metal; Preferably, the porous carbon material includes a porous carbon material manufactured using a polymer, biomass, or fossil fuel as a precursor, the porous metal oxide includes at least one of porous alumina, porous silica, and porous magnesium oxide, and the porous metal includes at least one of foamed nickel, porous titanium, and porous copper. The composite porous material according to claim 1 .

3. the mass ratio of the porous material A to the porous material B is 0.1 to 200; Preferably, in the composite porous material particles, An AB net structure is formed in which the porous material A and the porous material B are alternately distributed, and the mass ratio of the porous material A to the porous material B is 0.1 to 10; or An A@B core-shell structure is formed in which the porous material B encases the porous material A, and the mass ratio of the porous material A to the porous material B is 20 to 200, or The porous material C forms an AB@C net-like core-shell composite structure that encases an AB net-like structure in which the porous material A and the porous material B are alternately distributed, the mass ratio of the porous material A to the porous material B is 0.1 to 10, and the mass ratio of the total mass of the porous material A and the porous material B to the porous material C is 20 to 200. The composite porous material according to claim 1 .

4. The pore volume of the porous material A is 0.3 to 3.0 cm ３ / g, and the pore volume of the porous material B is 0.05 to 0.65 cm ３ / g, Preferably, in the porous material A, the ratio of pores having a pore diameter smaller than 10 nm to the total volume of pores in the porous material A is 60 to 100%, Preferably, in the porous material B, the proportion of pores having a pore diameter smaller than 10 nm to the total volume of pores in the porous material B is 60 to 100%. The composite porous material according to claim 1 .

5. Use of the composite porous material according to any one of claims 1 to 4 in battery anode materials, hydrogen storage materials, adsorption materials, catalyst supports, energy-saving materials, separation materials or drug loading.

6. silicon-based composite particles, the silicon-based composite particles include a composite porous substrate and a nanosilicon material dispersed within the pores of the porous substrate; the composite porous substrate comprises at least composition A and composition B, and the silicon-based composite particles accordingly comprise at least region A and region B; the A region comprises an A composition of a composite porous substrate and a nanosilicon material dispersed within its pores, and the B region comprises a B composition of a composite porous substrate and a nanosilicon material dispersed within its pores; the mass percent of nanosilicon material in the A region is greater than the mass percent of nanosilicon material in the B region; The composite porous substrate is a composite porous material according to any one of claims 1 to 4. A silicon-based composite material characterized by:

7. An AB net structure is formed in which the A region and the B region are alternately distributed, and the mass ratio of the A region to the B region is 0.1 to 10; or An A@B core-shell structure is formed in which the B region encases the A region, and the mass ratio of the A region to the B region is 20 to 200; or The C region forms an AB@C net-like core-shell composite structure that encloses the AB net-like structure in which the A region and the B region are alternately distributed, and the mass ratio of the A region to the B region is 0.1 to 10, and the mass ratio of the total mass of the A region and the B region to the C region is 20 to 200. The silicon-based composite material according to claim 6 .

8. the nanosilicon material is obtained by chemical vapor deposition of a silicon-containing precursor onto the composite porous substrate at 150-1000°C; Preferably, the silicon-containing precursor is one or more selected from monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silafluorene and its derivatives. The silicon-based composite material according to claim 6 .

9. The content of the nanosilicon material in the A region is 30 to 90 wt. %, and the content of the nanosilicon material in the B region is 0 to 50 wt. %; The silicon-based composite material according to claim 6 .

10. the silicon-based composite material further comprises a heteroatom X deposited within the pores of the composite porous material, the heteroatom X being non-silicon; Preferably, the heteroatom X is a non-metallic element, Preferably, the non-metallic element includes at least one of B, N, P, O and S; Preferably, in the silicon-based composite material, the content of the heteroatom X is 0 to 10 wt. %, more preferably, the content of the heteroatom X is 0 to 5 wt. %, Preferably, the heteroatom X in the pores of the composite porous material is obtained by chemical vapor deposition of a silicon-containing precursor and a heteroatom-containing precursor onto the composite porous substrate at 150-1000°C. The silicon-based composite material according to claim 6 .

11. The specific surface area of ​​the silicon-based composite material is 0.1 to 50 m ２ / g, and the pore volume is 0.001 to 0.5 cm ３ / g, and preferably, the specific surface area of ​​the silicon-based composite material is 0.1 to 5 m ２ / g, and the pore volume is 0.001 to 0.05 cm ３ / g, and / or The true density of the silicon-based composite material is 1.3 to 3.0 g / cm ３ and the closed pore volume is 0.01 to 0.30 cm ３ / g, and / or d of the silicon-based composite particles Ｖ,５０ is 5 to 20 μm, and the span (d Ｖ,９０ -d Ｖ,１０ ) / d Ｖ,５０ is 0.7 to 2.0, and preferably, the median diameter d Ｖ,５０ is 6 to 12 μm, and the span (d Ｖ,９０ -d Ｖ,１０ ) / d Ｖ,５０ is between 0.7 and 1.2, and / or The consolidated specific surface area of ​​the silicon-based composite material is 1 to 20 times, preferably 1 to 10 times, more preferably 1 to 5 times the specific surface area; and / or The silicon-based composite material has a silicon content of 10 to 90 wt. %, preferably 30 to 70 wt. %, and / or The silicon-based composite material further includes a coating layer located on the surface thereof, and preferably, the material of the coating layer is at least one selected from a solid electrolyte, a conductive polymer, a carbonaceous material, a metal, an alloy, a metal oxide, a metal hydroxide, a halogen-containing compound, a nitrogen-containing compound, a phosphorus-containing compound, a boron-containing compound, and a sulfur-containing compound, and more preferably, the material of the coating layer is a carbonaceous material. The silicon-based composite material according to claim 6 .

12. A negative electrode active material comprising the silicon-based composite material according to any one of claims 6 to 11, A negative electrode characterized by:

13. A battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode comprises a negative electrode active material comprising the silicon-based composite material according to any one of claims 6 to 11. A battery characterized by:

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