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

Abstract

The present invention particularly relates to the technical field of secondary batteries, and disclosed are a composite porous material and the use thereof, a silicon-based composite material, a negative electrode, and a battery. The composite porous material comprises composite porous material particles, and the composite porous material particles are formed by compounding two porous materials A and B or more having different pore structures. The distribution of the porous material A and the porous material B in the composite porous material particles is not limited, and the pore volume of the porous material A is greater than that of the porous material B. By compounding two materials having different pore volumes to form the composite porous material, a gradient difference in terms of the pore volume of the prepared composite porous material is formed, which is conducive to controlling the loading amount of a material in the pores and improving material change caused by the loading amount.

Description

Composite porous materials and their applications, silicon-based composite materials, negative electrodes and batteries

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to application number 2023115960582 filed with the China Patent Office on November 24, 2023, entitled “Composite porous materials and applications, silicon-based composite materials, negative electrodes and batteries,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present disclosure relates to the technical field of secondary batteries, and in particular to a composite porous material and application thereof, a silicon-based composite material, a negative electrode and a battery. Background Art

[0004] At present, silicon, with its extremely high theoretical specific capacity (4200mAh / g), is expected to replace graphite and become the next generation of high-energy-density lithium-ion battery negative electrode material, meeting the current market demand for high capacity and long life of lithium-ion batteries.

[0005] However, silicon undergoes significant volume expansion and contraction during repeated lithium insertion and delithiation, with expansion potentially reaching 300% when fully loaded. These repetitive, extreme volume changes lead to repeated formation of a solid-electrolyte interface within the composite material, resulting in battery capacity decay and poor cycling performance. High-capacity silicon-based composites contain a high silicon content, and the resulting expansion problem is particularly severe due to high silicon loading, hindering practical battery applications.

[0006] Dispersing silicon materials in porous materials to prepare silicon-based composite materials can limit the size of silicon materials and slow down the expansion of silicon-intercalated lithium to a certain extent. Porous materials are materials with a network structure composed of interconnected or closed pores. Most porous materials in the prior art have a regular pore structure and good performance homogeneity. However, when the porous material is used to prepare silicon-based negative electrode materials, the regular pore structure causes the silicon deposition amount to be basically consistent. The volume changes during the lithium insertion / delithiation process are carried out simultaneously. The stress generated by expansion or contraction can easily impact the pore structure of the porous material, affecting its structural stability, and further affecting the various electrochemical properties of the secondary battery. This effect is particularly prominent at high silicon content. Therefore, how to effectively alleviate the expansion stress of high-silicon negative electrodes and obtain better cycle stability is a technical problem that needs to be solved at present.

[0007] In view of this, the present disclosure is proposed.

[0008] Summary of the Invention

[0009] One of the objectives of the present disclosure is to provide a composite porous material, which is composed of porous materials with different pore structures.

[0010] A second object of the present disclosure is to provide an application of a composite porous material in battery negative electrode materials, hydrogen storage materials, adsorption materials, catalyst carriers, energy-saving materials, separation materials or drug loading.

[0011] The third purpose of the present disclosure is to provide a silicon-based composite material, which is composed of silicon-based materials with different silicon contents, so as to solve the problem of excessive lithium expansion when the composite material with uniform silicon content in the prior art is embedded in lithium at a high silicon content, and improve the cycle stability of the silicon-based composite material.

[0012] A fourth object of the present disclosure is to provide a negative electrode.

[0013] A fifth object of the present disclosure is to provide a battery.

[0014] In order to achieve the above-mentioned purpose of the present disclosure, the following technical solutions are adopted:

[0015] The first aspect of the present disclosure provides a composite porous material, which comprises composite porous material particles, wherein the composite porous material particles are composed of two or more porous materials with different pore structures; the composite porous material particles comprise 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 restricted; the pore volume of porous material A is greater than the pore volume of porous material B.

[0016] 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 oxyacid salt or a porous metal.

[0017] Preferably, the porous carbon material is at least one of a porous carbon material prepared by pyrolysis and / or activation using a polymer as a precursor, a porous carbon material prepared by pyrolysis and / or activation using biomass as a precursor, and a porous carbon material prepared by further pyrolysis and / or activation of fossil fuels; the porous carbon material includes but is not limited to hard carbon, amorphous carbon, carbon black, graphite, graphene, carbon nanotubes and coconut shell charcoal; the porous metal oxide includes but is not limited to at least one of porous alumina, porous silica and porous magnesium oxide; the porous metal includes but is not limited to at least one of foamed nickel, porous titanium and porous copper.

[0018] Furthermore, the mass ratio of the porous material A to the porous material B is 0.1-200.

[0019] Preferably, in the composite porous material particles, the porous material A and the porous material B are staggered and distributed to form an AB network structure, wherein the mass ratio of the porous material A to the porous material B is 0.1-10.

[0020] Alternatively, the porous material B wraps the porous material A to form an A@B core-shell structure, wherein the mass ratio of the porous material A to the porous material B is 20-200.

[0021] Alternatively, the porous material A and the porous material B are staggered to form an AB network structure, and there is a porous material C, which wraps the AB network structure to form an AB@C network-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.

[0022] Furthermore, the pore volume of the porous material A is 0.3 to 3.0 cm 3 / g, the pore volume of the porous material B is 0.05 to 0.65 cm 3 / g.

[0023] Preferably, in the porous material A, pores with a pore diameter of less than 10 nm account for 60 to 100% of the total pore volume of the porous material A.

[0024] Preferably, in the porous material B, pores with a pore diameter of less than 10 nm account for 60 to 100% of the total pore volume of the porous material B.

[0025] The second aspect of the present disclosure provides the use of the composite porous material in battery negative electrode materials, hydrogen storage materials, adsorption materials, catalyst carriers, energy-saving materials, separation materials or drug loading.

[0026] The third aspect of the present disclosure provides a silicon-based composite material, which comprises silicon-based composite material particles, which comprise a composite porous matrix and nano-silicon materials dispersed in the pores of the porous matrix. The composite porous matrix comprises at least component A and component B. Accordingly, the silicon-based composite material particles comprise at least region A and region B, wherein region A comprises component A of the composite porous matrix and nano-silicon materials dispersed in its pores, and region B comprises component B of the composite porous matrix and nano-silicon materials dispersed in its pores; the mass percentage of the nano-silicon materials in region A is greater than the mass percentage of the nano-silicon materials in region B.

[0027] Furthermore, the composite porous matrix is ​​the composite porous material according to the first aspect of the present disclosure; preferably, component A in the composite porous matrix is ​​the porous material A, and component B in the composite porous matrix is ​​the porous material B.

[0028] Furthermore, the A region and the B region are staggeredly distributed to form an AB network structure, wherein the mass ratio of the A region to the B region is 0.1 to 10.

[0029] Alternatively, the B region wraps the A region to form an A@B core-shell structure, wherein the mass ratio of the A region to the B region is 20-200.

[0030] Alternatively, the A region and the B region are staggered to form an AB network structure, and the C region exists, wrapping the AB network structure to form an AB@C network-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 mass ratio of the C region is 20 to 200.

[0031] Furthermore, the nano-silicon material is obtained by chemical vapor deposition of a silicon-containing precursor on the composite porous matrix at 150-1000°C; preferably, the silicon-containing precursor is selected from one or more of monosilane, disilane, trisilane, halosilane, polysilane, silole and its derivatives, and silanol and its derivatives.

[0032] Furthermore, the content of the nano-silicon material in the region A is 30 to 90 wt. %; and the content of the nano-silicon material in the region B is 0 to 50 wt. %.

[0033] Furthermore, the silicon-based composite material further includes a heteroatom X deposited in the pores of the composite porous material, and the heteroatom X is a non-silicon element.

[0034] Preferably, the heteroatom X is a non-metallic element.

[0035] Preferably, the non-metallic element includes at least one of B, N, P, O and S.

[0036] Preferably, in the silicon-based composite material, the content of the heteroatom X is 0 to 10 wt.%, and more preferably, the content of the heteroatom X is 0 to 5 wt.%.

[0037] 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 on the composite porous matrix at 150-1000°C.

[0038] Furthermore, the specific surface area of ​​the silicon-based composite material is 0.1 to 50 m 2 / g, pore volume of 0.001~0.5cm 3 / g; preferably, the specific surface area of ​​the silicon-based composite material is 0.1 to 5m 2 / g, pore volume of 0.001~0.05cm3 / g.

[0039] 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 0.01~0.30cm 3 / g.

[0040] And / or, the silicon-based composite material particles have a d V,50 5~20μm, the diameter distance (d V,90 -d V,10 ) / d V,50 is 0.7 to 2.0; preferably, the median particle size d of the silicon-based composite material V,50 6~12μm, diameter distance (d V,90 -d V,10 ) / d V,50 It is 0.7 to 1.2.

[0041] And / or, the compacted 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.

[0042] And / or, the content of silicon in the silicon-based composite material is 10-90 wt. %; preferably, the content of silicon in the silicon-based composite material is 30-70 wt. %.

[0043] And / or, it also includes a coating layer located on the surface of the silicon-based composite material; preferably, the material of the coating layer is selected from at least one of solid electrolytes, conductive polymers, carbonaceous materials, metals, alloys, metal oxides, metal hydroxides, halogen-containing compounds, nitrogen-containing compounds, phosphorus-containing compounds, boron-containing compounds and sulfur-containing compounds; further preferably, the material of the coating layer is a carbonaceous material.

[0044] A fourth aspect of the present disclosure provides a negative electrode, which comprises a negative electrode active material, wherein the negative electrode active material comprises the silicon-based composite material as described in the third aspect of the present disclosure.

[0045] 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, and the negative electrode active material comprises the silicon-based composite material as described in the third aspect of the present disclosure.

[0046] Compared with the prior art, the present disclosure has at least the following beneficial effects:

[0047] The composite porous material provided by the present disclosure is compounded using at least two materials with different pore volumes, so that the pore volume size of the prepared composite porous material forms regional differences, which is conducive to achieving controllable other physical and chemical properties in different regions, and achieving controllable loading capacity in different regions when used as a porous carrier, thereby realizing multi-level control and application of the material.

[0048] The application of the composite porous material provided by the present disclosure in battery negative electrode materials, hydrogen storage materials, adsorption materials, catalyst carriers, energy-saving materials, separation materials or drug loading provides composite porous materials with better performance for the above-mentioned fields, promotes the development of the above-mentioned fields, and broadens the application scope of downstream industries.

[0049] The silicon-based composite material provided by the present disclosure uses a composite porous material with controllable pore volume and pore size as a matrix, and forms a silicon-based composite material with controllable silicon content regional distribution after silicon deposition. In lithium-ion battery applications, the composite material particles have different lithium-intercalation expansion in regions with different silicon contents. The low silicon content region has a smaller expansion, which can buffer the high lithium-intercalation expansion in the high silicon content region, thereby alleviating the expansion inside the composite material particles, and improving the structural stability and cycle stability of the composite material. Furthermore, the composite porous material can be prepared into special structures such as networks or core-shells according to the different pore volume and pore size distributions, and silicon is vapor-deposited on this basis. In the formed composite material, regions with different silicon contents are staggered to form a network structure, or wrapped to form a core-shell structure; these specific structures can be designed in the composite material to have different silicon content distribution regions, forming a periodic distribution or gradient distribution of silicon content, further optimizing the buffering mechanism of silicon-intercalated lithium expansion, and improving the structural stability and cycle stability of the composite material.

[0050] On the other hand, different components of the composite porous matrix can have different distribution ratios of micropores, mesopores and macropores, which will enable the design of different distributions of silicon nanoparticle sizes in silicon-based composite materials, thereby forming a regionally controllable distribution of silicon content and silicon nanoparticle size in the composite material, further providing a silicon-intercalated lithium expansion buffering mechanism and improving the structural stability and cyclic stability of the composite material.

[0051] On the other hand, the composite porous matrices obtained from different precursors also have different microstructures within the bulk of the porous material, such as the carbon layer structure of carbon materials, including microscopic information such as interlayer spacing and degree of graphitization; such as the crystal phase structure of porous oxides, etc. The further combination of these microstructures into special structures such as networks or core-shells is also an important property of the composite porous matrix; after siliconization of the composite porous matrix, the resulting silicon-based composite material inherits the microporous structure of the composite porous matrix. These porous matrix components with different microstructures also play an important role in the overall performance of the silicon-based composite material.

[0052] The battery provided by the present disclosure uses a silicon-based composite material with better performance, improves 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 DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0054] FIG1 is a SEM photograph of the composite porous material provided in Example 1;

[0055] FIG2 is a SEM photograph of the composite porous material provided in Example 2. DETAILED DESCRIPTION

[0056] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0057] The endpoints of the ranges and any values ​​disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range 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.

[0058] The first aspect of the present disclosure provides a composite porous material, which comprises composite porous material particles, wherein the composite porous material particles are composed of two or more porous materials with different pore structures; the composite porous material particles comprise 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 restricted; the pore volume of porous material A is greater than the pore volume of porous material B.

[0059] The composite porous material provided by the present disclosure uses a compound of two materials with different pore volumes, so that the pore volume size of the prepared composite porous material forms regional differences, which is conducive to achieving controllable other physical and chemical properties in different regions, and achieving controllable loading capacity in different regions when used as a porous carrier, thereby realizing multi-level control and application of the material.

[0060] The present disclosure defines a composite porous material in which the pore volume of porous material A is greater than the pore volume of porous material B. The pores within the porous material are where the second phase is loaded, and the size of the pore volume determines the amount of loading. When the composite porous material is used as a substrate for a silicon-based negative electrode material for chemical vapor deposition, the amount of silicon loaded in porous material A will be greater than the amount of silicon loaded in porous material B in the resulting silicon-based composite material.

[0061] 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 oxyacid salt, or a porous metal.

[0062] Preferably, in some embodiments, the porous carbon material is at least one of a porous carbon material prepared by pyrolysis and / or activation using a polymer as a precursor, a porous carbon material prepared by pyrolysis and / or activation using biomass as a precursor, and a porous carbon material prepared by further pyrolysis and / or activation of fossil fuels; in some embodiments, the porous carbon material includes but is not limited to hard carbon, amorphous carbon, carbon black, graphite, graphene, carbon nanotubes and coconut shell charcoal, etc.

[0063] 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 oxyacid includes, but is not limited to, at least one of porous lithium titanate, porous aluminum phosphate, porous lithium phosphate, porous lithium aluminum phosphate, and porous lithium aluminum titanium phosphate; 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 the porous metal oxyacid is derived from a metal hydroxide, metal carbonate, double metal hydroxide, or polymetallic hydroxide; in some embodiments, the porous metal oxide or the porous metal oxyacid is derived from a sol or slurry of a metal hydroxide, metal carbonate, double metal hydroxide, polymetallic hydroxide, metal phosphate, or metal nitrate.

[0064] In some embodiments, the mass ratio of the porous material A to the porous material B is 0.1 to 200. Typically, but not limited to, the mass ratio of the porous material A to the porous material B is 0.1, 0.5, 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 150, 180 or 200, or any range therebetween.

[0065] Preferably, in some embodiments, in the composite porous material particles, the porous material A and the porous material B are staggered to form an AB network structure, wherein the mass ratio of the porous material A to the porous material B is 0.1 to 10;

[0066] In some embodiments, the porous material B wraps the porous material A to form an A@B core-shell structure, wherein the mass ratio of the porous material A to the porous material B is 20 to 200;

[0067] In some embodiments, the porous material A and the porous material B are staggered to form an AB network structure, and there is a porous material C that wraps the AB network structure to form an AB@C network-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 mass ratio of the porous material C is 20 to 200.

[0068] In some embodiments, the pore volume of the porous material A is 0.3 to 3.0 cm 3 / g, the pore volume of the porous material B is 0.05 to 0.65 cm 3 / g;

[0069] The pore volume of the porous material A can be, 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 or 3.0cm 3 / g, or any range between the two; the pore volume of the porous material B can be, for example, 0.05cm 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 or 0.65cm 3 / g, or any range of values ​​in between.

[0070] Preferably, in some embodiments, in the porous material A, the proportion of pores with a pore diameter of less than 10 nm in the total pore volume is 60-100%; typically but not limitatively, the proportion of pores with a pore diameter of less than 10 nm in the porous material A in the total pore volume may be, for example, 60%, 70%, 80%, 90% or 100%, or any range therebetween;

[0071] In some embodiments, the proportion of pores with a pore diameter less than 10 nm in the total pore volume of the porous material B is 60-100%. Typically, but not limiting, the proportion of pores with a pore diameter less than 10 nm in the total pore volume of the porous material B may be, for example, 60%, 70%, 80%, 90%, or 100%, or any range therebetween.

[0072] The second aspect of the present disclosure provides the use of the composite porous material as described in the first aspect of the present disclosure in battery negative electrode materials, hydrogen storage materials, adsorption materials, catalyst supports, energy-saving materials, separation materials or drug loading.

[0073] The composite porous material provided by the present disclosure has a designable, regionally distributed pore structure and specific surface area, which can achieve other controllable physical and chemical properties in different regions, making it extremely plastic in applications such as battery materials, hydrogen storage materials, adsorption materials, catalyst carriers, energy-saving materials, separation materials or drug loading, providing composite porous materials with better performance for the above fields, promoting the development of the above fields, and broadening the application scope of downstream industries. When the composite porous material is used as a porous carrier, it can achieve controllable loading capacity in different regions, thereby realizing multi-level control and application of composite materials; typically, when the composite porous material is used in a porous matrix of a silicon-based negative electrode material, the resulting composite material can achieve a regionally controllable silicon content distribution, alleviate the lithium embedding expansion of the silicon-based material in lithium battery applications, and improve its structural stability and cycle stability.

[0074] On the other hand, different components of the composite porous material may also have different pore distributions. For example, in some embodiments, porous material A is mainly mesopores, porous material B is mainly micropores, or porous material A and porous material B have different distribution ratios of micropores, mesopores and macropores, which will provide more possibilities for the various applications of composite porous materials.

[0075] On the other hand, the composite porous materials obtained from different precursors also have different microstructures within the bulk of the porous materials, such as the carbon layer structure of carbon materials, including microscopic information such as interlayer spacing and degree of graphitization; such as the crystal phase structure of porous oxides, etc. The further combination of these microstructures into special structures such as networks or core-shell structures is also an important property of composite porous materials, which can provide them with a broader application space.

[0076] When used as a hydrogen storage material, the composite porous material disclosed herein can enhance hydrogen storage capacity and optimize hydrogen distribution through its customizable, regionally distributed pore structure and specific surface area. Similarly, when used as a catalyst carrier, the composite porous material can achieve quantitative catalyst placement in different pore volume regions, enabling more precise control of reaction rates.

[0077] The energy-saving materials referred to in this disclosure include, but are not limited to, sound-absorbing or sound-insulating materials. Because composite porous materials have gradient or periodic pore volume regions, when sound strikes the surface of a composite porous material, a portion is reflected from the surface, while another portion is transmitted into the gradient pore structure, causing vibrations in the air within the pores. Due to viscosity and thermal conductivity, the sound energy is converted into heat and dissipated. The gradient pore structure allows sound waves to propagate repeatedly, resulting in a continuous conversion and dissipation of energy, thus achieving a sound-absorbing effect.

[0078] When the composite porous material provided by the present disclosure is used as a separation material, due to the design of regional pore volume distribution, different interception sites can be provided for different materials to be separated, thereby greatly improving the separation selectivity.

[0079] The composite porous material provided by the present disclosure can selectively design the main drug and excipients to be loaded in specific areas during drug loading due to the pore structure with adjustable regional distribution, thereby increasing the operating space for drug loading, facilitating binding with targeting ligands, and facilitating exerting effects within cells.

[0080] The third aspect of the present disclosure provides a silicon-based composite material, which comprises silicon-based composite material particles, which comprise a composite porous matrix and nano-silicon materials dispersed in the pores of the porous matrix. The composite porous matrix comprises at least component A and component B. Accordingly, the silicon-based composite material particles comprise at least region A and region B, wherein region A comprises component A of the composite porous matrix and nano-silicon materials dispersed in its pores, and region B comprises component B of the composite porous matrix and nano-silicon materials dispersed in its pores; the mass percentage of the nano-silicon materials in region A is greater than the mass percentage of the nano-silicon materials in region B.

[0081] The silicon-based composite material disclosed herein uses a composite porous material with controllable pore volume and pore size as a matrix. After silicon deposition, it forms a silicon-based composite material with a controllable regional distribution of silicon content. In lithium-ion battery applications, the composite particles experience different lithium expansion in regions with different silicon contents. The smaller expansion in regions with low silicon content can buffer the higher lithium expansion in regions with high silicon content, thereby alleviating internal expansion in the composite particles and improving the structural and cyclic stability of the composite.

[0082] On the other hand, different components of the composite porous matrix may also have different pore distributions. For example, in some embodiments, component A is mainly mesopores and component B is mainly micropores, or components A and B have different distribution ratios of micropores, mesopores and macropores. This will enable the design of different distributions of silicon nanoparticle sizes in silicon-based composite materials, thereby forming a regionally controllable distribution of silicon content and silicon nanoparticle size in the composite material, further providing a silicon-intercalated lithium expansion buffering mechanism, and improving the structural stability and cyclic stability of the composite material.

[0083] On the other hand, the composite porous matrices obtained from different precursors also have different microstructures within the bulk of the porous material, such as the carbon layer structure of carbon materials, including microscopic information such as interlayer spacing and degree of graphitization; such as the crystal phase structure of porous oxides, etc. The further combination of these microstructures into special structures such as networks or core-shells is also an important property of the composite porous matrix; after siliconization of the composite porous matrix, the resulting silicon-based composite material inherits the microporous structure of the composite porous matrix. These porous matrix components with different microstructures also play an important role in the overall performance of the silicon-based composite material.

[0084] In some embodiments, the present disclosure provides a silicon-based composite material, wherein the composite porous matrix is ​​the composite porous material according to the first aspect of the present disclosure; preferably, component A in the composite porous matrix is ​​the porous material A according to the first aspect of the present disclosure, and component B in the composite porous matrix is ​​the porous material B according to the first aspect of the present disclosure.

[0085] In some embodiments, in the silicon-based composite material provided by the present disclosure, the A region and the B region are staggered to form an AB network structure, wherein the mass ratio of the A region to the B region is 0.1 to 10;

[0086] In some embodiments, the B region wraps the A region to form an A@B core-shell structure, wherein the mass ratio of the A region to the B region is 20 to 200;

[0087] In some embodiments, the A region and the B region are staggered to form an AB network structure, and there is a C region that wraps the AB network structure to form an AB@C network-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 mass ratio of the C region is 20 to 200.

[0088] In some embodiments, the nano-silicon material is obtained by chemical vapor deposition of a silicon-containing precursor on the composite porous substrate at a temperature of 150-1000°C. Preferably, in some embodiments, the silicon-containing precursor is selected from one or more of monosilane, disilane, trisilane, halosilanes, polysilanes, siloles and their derivatives, and silanols and their derivatives. Preferably, in some embodiments, the temperature at which the silicon-containing precursor contacts the porous substrate is 200-700°C.

[0089] In some embodiments, the mass percentage of the nano-silicon material in region A is 30-90%, and the mass percentage of the nano-silicon material in region B is 0-50%. The regionally distributed silicon content is determined by the regionally distributed pore volume in the composite porous matrix. In the present disclosure, the regionally distributed silicon content is the primary factor controlling the expansion of lithium-intercalated silicon in the buffer composite particles.

[0090] Typically but not limitatively, in some embodiments, the mass percentage of the nano-silicon material in region A can be, for example, 30%, 40%, 50%, 60%, 70%, 80% or 90% or a range between any two values; the mass percentage of the nano-silicon material in region B can be, for example, 0, 10%, 20%, 30%, 40% or 50% or a range between any two values, and a content of 0 indicates that no nano-silicon material is deposited in region B.

[0091] In some embodiments, the silicon-based composite material further comprises a heteroatom X deposited in the pores of the composite porous material, wherein the heteroatom X is a non-silicon element;

[0092] Preferably, in some embodiments, the heteroatom X is a non-metallic element;

[0093] Preferably, in some embodiments, the non-metallic element includes at least one of B, N, P, O and S;

[0094] Preferably, in some embodiments, the content of the heteroatom X in the silicon-based composite material is 0 to 10 wt. %; further preferably, in some embodiments, the content of the heteroatom X is 0 to 5 wt. %;

[0095] Preferably, in some embodiments, 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 on the composite porous matrix at a temperature of 150-1000°C. Preferably, in some embodiments, the temperature at which the silicon-containing precursor and the heteroatom-containing precursor are in contact with the porous matrix is ​​200-700°C. The silicon-containing precursor is selected from one or more of monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silanol and its derivatives. The heteroatom-containing precursor is a precursor containing the heteroatom element and is introduced 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, or a boron-containing precursor.

[0096] The manner in which the silicon-containing precursor and the heteroatom-containing precursor are in contact with the porous matrix includes: the silicon-containing precursor and the heteroatom-containing precursor are contacted with the porous matrix alternately; or, the silicon-containing precursor and the heteroatom-containing precursor are contacted with the porous matrix simultaneously; or, the silicon-containing precursor and a mixed gas comprising the silicon-containing precursor and the heteroatom-containing precursor are contacted with the porous matrix alternately. Preferably, the silicon-containing precursor is in continuous contact with the porous matrix, and the heteroatom-containing precursor is intermittently introduced during this process.

[0097] In some embodiments, the specific surface area of ​​the silicon-based composite material is 0.1 to 50 m 2 / g, pore volume of 0.001~0.5cm 3 / g; Preferably, in some embodiments, the specific surface area of ​​the silicon-based composite material is 0.1 to 5m 2 / g, pore volume of 0.001~0.05cm 3 / g; too high a specific surface area can easily lead to an increase in side reactions in lithium battery applications and a decrease in the initial Coulombic efficiency of the composite material. Too low a specific surface area is difficult to achieve.

[0098] In some embodiments, the true density of the silicon-based composite material is 1.3 to 3.0 g / cm 3 , the closed pore volume is 0.01~0.30cm 3 / g;

[0099] In this article, the skeleton density of the material obtained by the helium pycnometry is referred to as the true density of the material. The closed-pore volume is calculated by subtracting the volume of the corresponding fully dense material of the same elemental composition from the skeleton volume of the composite material, where the skeleton volume of the composite material is the reciprocal of the true density of the composite material. The skeleton volume of the composite material consists of two parts, one is the volume of the corresponding fully dense material of the same elemental composition, and the other is the closed-pore volume; the volume of the fully dense material is the reciprocal of its true density (i.e., the theoretical density of the fully dense material of the same elemental composition); based on this, the closed-pore volume of the composite material can be calculated. A certain amount of closed-pore volume can provide a buffer space for the expansion of silicon-intercalated lithium in the composite material, thereby improving the cyclic stability of the composite material; however, too much closed pore volume will lead to a decrease in the structural strength of the composite material, a decrease in the compaction density, and poor battery processing performance. At the same time, the reduced structural strength will also cause a decrease in the cyclic stability of the composite material. Therefore, it is necessary to control the true density and closed-pore volume of the composite material within a certain range.

[0100] Typically, but not limiting, in some embodiments, the true density of the silicon-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 or 3.0g / cm 3 or any range therebetween; in some embodiments, the closed pore volume may be 0.01 cm 3 / g, 0.05cm 3 / g, 0.1cm 3 / g, 0.15cm 3 / g, 0.2cm 3 / g, 0.25cm 3 / g or 0.30cm 3 / g or any range of values ​​in between.

[0101] In some embodiments, the silicon-based composite material particles have a d V,50 5~20μm, the diameter distance (d V,90 -d V,10 ) / d V,50 is 0.6 to 2.0; preferably, the median particle size d of the silicon-based composite material V,50 6~12μm, diameter distance (d V,90 -d V,10 ) / d V,50 The silicon-based composite material needs to have a suitable gradation to show better lithium battery processing and application performance.

[0102] In some embodiments, the compacted 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; the compacted specific surface area refers to the specific surface area of ​​the silicon-based composite material at 4000 kgf / cm 2 The specific surface area of ​​a material after compaction under pressure. Compacted specific surface area is a measure of the structural stability of a material. The lower the compacted specific surface area of ​​a material, the smaller the ratio of its compacted specific surface area to its specific surface area, the more resistant it is to compaction, and the higher its compressive strength, which will improve the mechanical stability of the composite material.

[0103] In some embodiments, the silicon content of the silicon-based composite material is 10-90%; preferably, in some embodiments, the silicon content of the silicon-based composite material is 30-70%.

[0104] In some embodiments, it further includes a coating layer located on the surface of the silicon-based composite material; preferably, in some embodiments, the material of the coating layer is selected from at least one of solid electrolytes, conductive polymers, carbonaceous materials, metals, alloys, metal oxides, metal hydroxides, halogen-containing compounds, nitrogen-containing compounds, phosphorus-containing compounds, boron-containing compounds and sulfur-containing compounds; further preferably, in some embodiments, the material of the coating layer is a carbonaceous material.

[0105] A fourth aspect of the present disclosure provides a negative electrode, wherein the negative electrode comprises a negative electrode active material, and the negative electrode active material comprises the silicon-based composite material described in the third aspect of the present disclosure.

[0106] 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, and the negative electrode active material comprises the silicon-based composite material described in the third aspect of the present disclosure.

[0107] The battery provided by the present disclosure uses a silicon-based composite material with a regional thyristor content, which can reduce the expansion of silicon-embedded lithium in particles under conditions of higher silicon content and high capacity, improve the cycle stability and structural stability of the secondary battery, and promote the development of downstream industries.

[0108] The present disclosure is further illustrated below by specific examples and comparative examples. However, it should be understood that these examples are merely for the purpose of further explanation and are not to be construed as limiting the present disclosure in any manner. The raw materials used in the examples and comparative examples herein, unless otherwise specified, were prepared under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, for which the manufacturer is not specified, are all commercially available conventional products.

[0109] Example 1

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

[0111] Sucrose and lignin were mixed in a mass ratio of 1:1. The resulting mixture was heated from room temperature to 900°C at a rate of 2°C / min in a N2 atmosphere and maintained at this temperature for 2 hours. CO2 was then introduced and maintained for another 2 hours. The mixture was cooled and crushed and graded to obtain a composite porous material.

[0112] Example 2

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

[0114] The sucrose was heated from room temperature to 900°C at a rate of 2°C / min in an N2 atmosphere and maintained at this temperature for 2 hours; the core carbon material was obtained after crushing and grading; the core carbon material was mixed with asphalt 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 an N2 atmosphere, then CO2 was introduced and maintained for another 2 hours, cooled, and crushed and graded to obtain a composite porous material.

[0115] Example 3

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

[0117] 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 an N2 atmosphere and held at this temperature for 2 hours. CO2 was then introduced and held for another 2 hours. The mixture was then cooled, crushed, and graded to produce an alumina-sucrose carbon composite. The alumina-sucrose carbon composite was then placed in a 0.01M HCl solution and stirred for 2 hours. The mixture was then filtered, washed, and dried, followed by sintering at 400°C to obtain a porous composite material.

[0118] Example 4

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

[0120] Sucrose and lignin were mixed in a 1:1 mass ratio. The resulting mixture was heated from room temperature to 800°C at a rate of 2°C / min in an N2 atmosphere and held at this temperature for 2 hours. The resulting material was crushed and graded, then mixed with asphalt in a 50:1 mass ratio. The mixture was heated to 900°C in an N2 atmosphere, held for 2 hours, and then CO2 was introduced and held for 2 hours to produce a composite porous material.

[0121] Example 5

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

[0123] 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 maintained at this temperature for 2 hours to obtain a composite porous material.

[0124] Example 6

[0125] This embodiment provides a composite porous material, and the preparation process is as follows:

[0126] Sucrose and lignin were mixed in a mass ratio of 1:1. The resulting mixture was pre-oxidized at 200°C and then heated from room temperature to 900°C at a rate of 2°C / min in a nitrogen atmosphere and maintained at this temperature for 2 hours. CO2 was introduced and the mixture was maintained at 1000°C for 3 hours to obtain a composite porous material.

[0127] Comparative Example 1

[0128] This comparative example provides a sucrose carbon, and the preparation process is as follows: sucrose is heated from room temperature to 900°C at 2°C / min in an N2 atmosphere and maintained at this temperature for 2 hours; CO2 is introduced instead, and maintained for another 2 hours, and the temperature is lowered, and sucrose carbon is obtained after crushing and classification.

[0129] Comparative Example 2

[0130] This comparative example provides a lignin carbon, and the preparation process is as follows: lignin is heated from room temperature to 900°C at 2°C / min in an N2 atmosphere and maintained at this temperature for 2 hours; CO2 is introduced instead, and maintained for another 2 hours, and then the temperature is lowered, and lignin carbon is obtained after crushing and classification.

[0131] Comparative Example 3

[0132] This comparative example provides a coconut shell charcoal, which is commercially available and has an iodine value of 800 and 20-60 mesh particles.

[0133] Comparative Example 4

[0134] This comparative example provides a porous alumina, which is the same as the porous alumina used in Example 3.

[0135] Test Example 1

[0136] The pore volumes of the composite porous materials obtained in Examples 1 to 6 and the porous materials provided in Comparative Examples 1 to 4 were measured respectively; as well as the mass ratios of the various components in the composite porous materials.

[0137] The pore volume was determined by calculating the adsorption amount at the maximum N2 adsorption partial pressure (p / p0>0.99).

[0138] The pore volumes of the porous material A and the porous material B in the composite porous material are obtained by calculation: the pore volumes of the porous material A and the porous material B constituting the structure are measured separately to obtain the pore volumes of each part in the composite porous material.

[0139] In the composite porous material, the mass ratio of each part is also obtained by converting the mass of each part after carbonization and / or activation.

[0140] The results are shown in Table 1 below.

[0141] Table 1 Performance data of composite porous materials

[0142] Example 7

[0143] This embodiment provides a silicon-based composite material, and the process is as follows:

[0144] The composite porous material obtained in Example 1 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in the 20% SiH4-N2 mixture for 30 h; after the mixture was changed to N2, the temperature was naturally lowered, crushed and classified to obtain d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0145] Example 8

[0146] This embodiment provides a silicon-based composite material, and the process is as follows:

[0147] The composite porous material obtained in Example 2 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in the 20% SiH4-N2 mixture for 30h; after the mixture was changed to N2 atmosphere, the temperature was naturally lowered, crushed and classified to obtain d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0148] Example 9

[0149] This embodiment provides a silicon-based composite material, and the process is as follows:

[0150] The composite porous material obtained in Example 3 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in the 20% SiH4-N2 mixture for 30 h; after the mixture was changed to N2, the temperature was naturally lowered, crushed and classified, and d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0151] Example 10

[0152] This embodiment provides a silicon-based composite material, and the process is as follows:

[0153] The composite porous material obtained in Example 4 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in the 20% SiH4-N2 mixture for 30 h; after the mixture was changed to N2, the temperature was naturally lowered, crushed and classified, and d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0154] Example 11

[0155] This embodiment provides a silicon-based composite material, and the process is as follows:

[0156] The composite porous material obtained in Example 5 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in a 20% SiH4-N2 mixture for 5 h; N2 was purged for 2 h; the mixture was changed to 10% C2H2-N2 and kept for 2 h; after the mixture was changed to N2, the temperature was naturally lowered, crushed and classified, and d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0157] Example 12

[0158] This embodiment provides a silicon-based composite material, and the process is as follows:

[0159] The composite porous material obtained in Example 6 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in the 20% SiH4-N2 mixture for 50 h; after the mixture was changed to N2, the temperature was naturally lowered, crushed and classified to obtain d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0160] Example 13

[0161] This embodiment provides a silicon-based composite material. Unlike Example 7, the obtained silicon-based composite material particles are dispersed in a 5% AlPO4 aqueous solution, wherein the mass ratio of the silicon-based composite material to AlPO4 is 1:5, and the mixture is ultrasonicated, stirred, and excess liquid is filtered. After drying in an 80°C oven, the mixture is sintered at 400°C for 2h in a N2 atmosphere to obtain an AlPO4-coated silicon-based composite material.

[0162] Example 14

[0163] The composite porous material obtained in Example 1 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C for 30h in a 20% SiH4-0.01% O2-N2 mixture; after the mixture was changed to N2 atmosphere, the temperature was naturally lowered, crushed and classified to obtain d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0164] Comparative Example 5

[0165] The porous material provided in Comparative Example 1 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the atmosphere was changed to a 20% SiH4-N2 mixed gas and kept at 600°C for 30 hours in a 20% SiH4-N2 mixed atmosphere; after the atmosphere was changed to N2, the temperature was naturally lowered, crushed and classified, and d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0166] Comparative Example 6

[0167] The porous material provided in Comparative Example 2 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in the 20% SiH4-N2 mixture for 20 h; after the mixture was changed to N2, the temperature was naturally lowered, crushed and classified, and d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0168] Comparative Example 7

[0169] The porous material provided in Comparative Example 3 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C in the 20% SiH4-N2 mixture for 25h; after the mixture was changed to N2 atmosphere, the temperature was naturally lowered, crushed and classified to obtain d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0170] Comparative Example 8

[0171] The porous material provided in Comparative Example 4 was placed in a tube furnace and heated from room temperature to 600°C at 2°C / min in a N2 atmosphere; then the mixture was changed to 20% SiH4-N2 and kept at 600°C for 15h in the 20% SiH4-N2 mixture; after the mixture was changed to N2 atmosphere, the temperature was naturally lowered, crushed and classified to obtain d V,50 Silicon-based composite material with a diameter of 10μm and a diameter pitch of 0.88.

[0172] Test Example 2

[0173] The data of 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.

[0174] Table 2 Silicon content data of silicon-based composite materials

[0175] Test Example 3

[0176] The electrochemical performance of the silicon-based composite materials obtained in Examples 7 to 14 and Comparative Examples 5 to 8 was tested:

[0177] 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 prepare negative electrode sheets, which were used to prepare CR2032 button batteries using conventional methods, and the batteries were tested for electrical properties.

[0178] The specific test method is:

[0179] (1) Half-cell assembly: CR2032 button cells were assembled in a glove box, with a lithium metal sheet as the counter electrode, a polypropylene microporous membrane as the separator, and the electrolyte being a mixture of LiPF6 dissolved in ethyl carbonate (EC) and diethyl carbonate (DEC) (volume ratio EC:DEC = 1:1), where the LiPF6 concentration was 1 mol / L.

[0180] The battery was tested for charge and discharge using the LAND battery testing system.

[0181] (2) Cyclic gram capacity and first efficiency test: After the CR2032 battery is left uncharged for 6 hours, it is discharged at 0.05C to 0.005V, and then discharged at 0.01C to 0.005V; after standing for 5 minutes, it is charged at a constant current of 0.05C to 1.5V; the first delithiation gram capacity is the gram capacity (or mass specific capacity) of the electrode material, and the ratio of the first delithiation capacity to the first lithium insertion capacity is the first coulombic efficiency of the battery.

[0182] (3) Electrode expansion rate test: After the CR2032 battery was left to rest for 6 hours, it was discharged at 0.05C to 0.005V, and then at 0.01C to 0.005V. The battery was then disassembled in a glove box, the electrode was cleaned with DEC, and the electrode thickness was measured. The expansion rate was calculated as: (first fully charged electrode thickness - fresh electrode thickness) / fresh electrode thickness × 100%.

[0183] Full battery preparation and electrochemical performance testing:

[0184] The silicon-based composite materials obtained in Examples 7-14 and Comparative Examples 5-8 were used as negative electrode active materials. The electrodes containing the negative electrode active materials were prepared using conventional methods to prepare soft-pack batteries and undergo electrical performance testing. The soft-pack batteries were prepared in a dehumidified room with a dew point of -45°C. The batteries were subjected to charge and discharge cycle testing using a LANBTS battery testing system. The results are shown in Table 3. The specific testing methods are as follows:

[0185] (1) Preparation of positive electrode sheet: The positive electrode active material LiCoO2, the conductive agent Super P, the binder PVDF and the solvent NMP were stirred and mixed in a mass ratio of 92:3:5:150, and then evenly coated on the positive electrode current collector, and then dried at 80°C to obtain the positive electrode sheet.

[0186] (2) Preparation of negative electrode sheet: The negative electrode active material, conductive agent Super P, binder polyacrylic acid and solvent deionized water were stirred and mixed in a mass ratio of 95:1:4:120, and then evenly coated on the negative electrode current collector, and then dried at 100°C to obtain the negative electrode sheet.

[0187] (3) The positive and negative electrodes are stacked in a square shape and separated by a polypropylene separator to form a battery core. The core is then encapsulated in an aluminum-plastic bag. An electrolyte of the corresponding capacity is injected into the bag and vacuum-sealed to obtain a soft-pack battery. The electrolyte is a mixture of LiPF6, EC, and DEC, with a LiPF6 concentration of 1 mol / L and a volume ratio of EC to DEC of 1:1.

[0188] (4) Formation: After filling and sealing, the battery begins to form. It is placed in a 25°C constant temperature box for 12 hours, then charged to 3.3V at 0.02C constant current, allowed to stand for 30 minutes, charged to 3.8V at 0.025C constant current, allowed to stand for 10 minutes, and charged to 4.2V at 0.33C constant current. The formed battery is vacuumed and the air bag is sheared, and then the capacity is divided. It is charged to 4.45V at 0.33C constant current, allowed to stand for 10 minutes, discharged to 3V at 1C constant current, allowed to stand for 10 minutes, and discharged to 3V at 0.33C constant current. The capacity division is completed. The ratio of the discharge capacity divided by the charge capacity in the soft pack battery formation is the battery's initial efficiency.

[0189] (5) 25℃ cycle test: Place the battery in a 25℃ constant temperature box, charge it to 4.45V at a constant current of 1C, and then charge it to 0.1C at a constant voltage of 4.45V; after standing for 10 minutes, discharge it to 3.0V at a constant current of 1C, and stand it for 10 minutes. Repeat the above charging and discharging steps until the discharge capacity is lower than 80% of the discharge capacity of the first cycle. The number of cycles obtained at this time is the cycle life of the soft-pack battery; record the capacity retention rate after 100 cycles.

[0190] The obtained data are shown in Table 3 below.

[0191] Table 3 Electrochemical performance data of silicon-based composite materials

[0192] Examples 1 to 6 use different combinations of different precursors to obtain composite porous materials with different structures such as AB network structure, A@B core-shell structure and AB@C network-core-shell composite structure, as well as different regional pore volumes; Comparative Examples 1 and 2 use a single carbon source precursor to prepare porous materials with a single pore volume, and Comparative Examples 3 and 4 are commercially available porous materials, which are also porous materials with a single component and a single pore volume.

[0193] Comparative Examples 5 to 8 used the porous materials of Comparative Examples 1 to 4 as porous matrices to prepare silicon-based composite materials. Examples 7 to 14 used the composite porous materials with regionally distributed pore volumes obtained in Examples 1 to 6 as composite porous matrices to deposit silicon, thereby obtaining silicon-based composite materials.

[0194] Combining Tables 1, 2, and 3, it can be seen that compared to the silicon-based composite materials prepared using porous materials with a single pore volume in Comparative Examples 5 to 8, the silicon-based composite materials of Examples 7 to 14 have lower electrode expansion rates and 100-cycle capacity retention rates. The 100-cycle capacity retention of the silicon-based composite materials of Comparative Examples 5 to 8 is all below 92%; the 100-cycle capacity retention of the silicon-based composite materials of Examples 7 to 14 is all above 97%. Exceptionally, Example 12 uses the high-pore-volume composite porous material of Example 6 as the porous matrix for silicon deposition, resulting in a composite material with a higher silicon content (62.4%) and a 1.5V gram capacity of up to 2320 mAh / g. Its 100-cycle capacity retention rate is relatively low at 94.5%, still higher than that of the comparative example. The composite porous material used in Example 11 has a lower pore volume, so the resulting silicon-based composite material has a lower silicon content and a lower gram capacity.

[0195] Examples 7 to 12 use the composite porous materials of Examples 1 to 6 as composite porous matrices; Examples 13 and 14 both use the composite porous material of Example 1 as composite porous matrices. The difference from Example 7 is that Example 13 coats the silicon-based composite material with an inorganic electrolyte, and the 100-cycle capacity retention rate is further improved; Example 14 introduces oxygen heteroatoms during the silicon deposition process to form Si-O-Si or SiO in the silicon-based composite material. x In local areas, strong Si-O bonds form constraints on the expansion of silicon-embedded lithium, further reducing the expansion rate of the material electrode and improving the cycle stability of the silicon-based composite material. Its 100-cycle capacity retention reaches 99.2%.

[0196] Test Example 4

[0197] A scanning electron microscopy (SEM) photograph of the composite porous material provided in Example 1 was performed, and the resulting SEM image is shown in Figure 1. As can be seen from Figure 1, the composite porous material has two regions with different pore structures. The upper left and lower right corners of the image represent the loose, porous region, porous material A, with a dense region sandwiched between them, porous material B. Due to the limitations of the SEM resolution, micropores in the composite porous material cannot be observed. However, according to common knowledge in the art, in the composite porous material of Example 1, both porous material A and porous material B contain micropores. At a larger scale, porous material A and porous material B are interlaced, forming an AB network structure.

[0198] The composite porous material provided in Example 2 was subjected to scanning electron microscopy, and the obtained SEM photograph is shown in FIG2 . As can be seen from FIG2 , the inner and outer shell of the composite porous material exhibit different densities, forming an A@B core-shell structure.

[0199] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure. Industrial Applicability

[0200] The composite porous material provided by the present disclosure can be applied to fields such as battery negative electrode materials, hydrogen storage materials, adsorption materials, catalyst carriers, energy-saving materials, separation materials or drug loading, providing composite porous materials with better performance for the above fields, promoting the development of the above fields, and broadening the application scope of downstream industries.

Claims

1. A composite porous material, characterized in that: The composite porous material comprises composite porous material particles, and the composite porous material particles are composited by two or more porous materials with different pore structures; The composite porous material particles at least comprise porous material A and porous material B, and the distribution of the porous material A and porous material B in the composite porous material particles is not restricted; The pore volume of the porous material A is greater than the pore volume of the porous material B.

2. The composite porous material according to claim 1, characterized in that: The porous material A is a porous carbon material; the porous material B is at least one of a porous carbon material, a porous metal oxide, a porous metal oxyacid salt or a porous metal; Preferably, the porous carbon material includes a porous carbon material prepared 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; the porous metal includes at least one of foamed nickel, porous titanium and porous copper.

3. The composite porous material according to claim 1, characterized in that: 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, The porous material A and the porous material B are staggered to form an AB network structure, wherein the mass ratio of the porous material A to the porous material B is 0.1 to 10; Or, the porous material B wraps the porous material A to form an A@B core-shell structure, wherein the mass ratio of the porous material A to the porous material B is 20 to 200; Or, the porous material A and the porous material B are staggered to form an AB network structure, and there is a porous material C, which wraps the AB network structure to form an AB@C network-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 mass ratio of the porous material C is 20 to 200.

4. The composite porous material according to claim 1, characterized in that: The pore volume of the porous material A is 0.3 to 3.0 cm 3 / g, the pore volume of the porous material B is 0.05-0.65cm 3 / g; Preferably, in the porous material A, pores with a pore size of less than 10 nm account for 60 to 100% of the total pore volume of the porous material A; Preferably, in the porous material B, pores with a pore diameter of less than 10 nm account for 60-100% of the total pore volume in the porous material B.

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

6. A silicon-based composite material, characterized in that: The silicon-based composite material comprises silicon-based composite material particles, the silicon-based composite material particles comprise a composite porous matrix and nano-silicon materials dispersed in the pores of the porous matrix, the composite porous matrix comprises at least component A and component B, and accordingly the silicon-based composite material particles comprise at least region A and region B, the region A comprises component A of the composite porous matrix and nano-silicon materials dispersed in its pores, the region B comprises component B of the composite porous matrix and nano-silicon materials dispersed in its pores; the mass percentage of the nano-silicon materials in the region A is greater than the mass percentage of the nano-silicon materials in the region B; The composite porous matrix is ​​the composite porous material according to any one of claims 1 to 4.

7. The silicon-based composite material according to claim 6, characterized in that: The A region and the B region are staggered to form an AB network structure, wherein the mass ratio of the A region to the B region is 0.1 to 10; Or, the B region wraps the A region to form an A@B core-shell structure, wherein the mass ratio of the A region to the B region is 20 to 200; Alternatively, the A region and the B region are staggered to form an AB network structure, and there is a C region that wraps the AB network structure to form an AB@C network-core-shell composite structure, wherein the mass ratio of the A region to the B region is 0.1 to 10, and the total mass ratio of the A region and the B region to the mass ratio of the C region is 20 to 200.

8. The silicon-based composite material according to claim 6, characterized in that: The nano-silicon material is obtained by chemical vapor deposition of a silicon-containing precursor on the composite porous substrate at 150-1000° C.; preferably, the silicon-containing precursor is selected from one or more of monosilane, disilane, trisilane, halosilanes, polysilanes, silole and its derivatives, and silanol and its derivatives.

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

10. The silicon-based composite material according to claim 6, characterized in that: The silicon-based composite material further includes a heteroatom X deposited in the pores of the composite porous material, wherein the heteroatom X is a non-silicon element; 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. %; further 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 on the composite porous substrate at 150-1000°C.

11. The silicon-based composite material according to claim 6, characterized in that: The specific surface area of ​​the silicon-based composite material is 0.1 to 50 m 2 / g, pore volume is 0.001~0.5cm 3 / g; preferably, the specific surface area of ​​the silicon-based composite material is 0.1 to 5m 2 / g, pore volume is 0.001~0.05cm 3 / g; And / or, the true density of the silicon-based composite material is 1.3-3.0 g / cm 3 , closed pore volume is 0.01~0.30cm 3 / g; And / or, the silicon-based composite material particles have a d V,50 5~20μm, diameter distance (d V,90 -d V,10 ) / d V,50 is 0.7 to 2.0; preferably, the median particle size d of the silicon-based composite material V,50 6~12μm, diameter distance (d V,90 -d V,10 ) / d V,50 0.7~1.2; and / or, the compacted 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, in the silicon-based composite material, the content of silicon is 10 to 90 wt.%; preferably, in the silicon-based composite material, the content of silicon is 30 to 70 wt.%; And / or, it also includes a coating layer located on the surface of the silicon-based composite material; preferably, the material of the coating layer is selected from at least one of solid electrolytes, conductive polymers, carbonaceous materials, metals, alloys, metal oxides, metal hydroxides, halogen-containing compounds, nitrogen-containing compounds, phosphorus-containing compounds, boron-containing compounds and sulfur-containing compounds; further preferably, the material of the coating layer is a carbonaceous material.

12. A negative electrode, characterized in that The negative electrode comprises a negative electrode active material, and the negative electrode active material comprises the silicon-based composite material according to any one of claims 6 to 11.

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

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