CN110098404B - Nano porous silicon with step structure, sintering-etching preparation method and application thereof - Google Patents

Nano porous silicon with step structure, sintering-etching preparation method and application thereof Download PDF

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CN110098404B
CN110098404B CN201910404768.8A CN201910404768A CN110098404B CN 110098404 B CN110098404 B CN 110098404B CN 201910404768 A CN201910404768 A CN 201910404768A CN 110098404 B CN110098404 B CN 110098404B
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silicon
sintering
nano porous
etching
porous silicon
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CN110098404A (en
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吴振国
杨志伟
郭孝东
钟本和
陈彦逍
向伟
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Sichuan University
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Sichuan University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention belongs to the technical field of energy storage materials, and particularly relates to nano porous silicon with a step structure, a sintering-etching preparation method and application thereof. Aiming at the problems that most preparation methods in the prior art can only prepare common nano porous silicon structures and can not effectively solve the problem of volume expansion of silicon as a lithium ion battery cathode material, the technical scheme of the invention is as follows: the structure can provide space required in the volume expansion process, effectively reduce stress accumulation, and slow down or eliminate the damage of volume strain to the silicon cathode structure in the lithium intercalation and lithium deintercalation processes. The development of the electric automobile needs the development of the energy storage battery towards high energy density, silicon becomes the most possible next generation lithium ion cathode material with the ultrahigh specific energy density, and the invention can solve the expansion problem and can greatly promote the application of the energy storage battery in the traffic field.

Description

Nano porous silicon with step structure, sintering-etching preparation method and application thereof
Technical Field
The invention belongs to the technical field of energy storage materials, and particularly relates to nano porous silicon with a step structure, a sintering-etching preparation method and application thereof.
Background
Silicon has the advantages of large basic reserve and high theoretical capacity, and is an ideal material for the cathode of the lithium ion battery. However, the silicon cathode has the volume expansion and shrinkage problem of up to 300-400% during charging and discharging, and the application of the silicon cathode in the field of energy storage is severely restricted. The stress generated by the lithiation expansion process of the silicon negative electrode is a process that increases sequentially from the center of the particle to the surface of the particle. Nanoporous silicon with a specific structure is a viable means to solve this problem.
The preparation technology of the nano porous silicon is more, such as silicon alloy etching, silicon magnesium alloy evaporation, silicon dioxide magnesiothermic reduction and the like. But the prior art mostly makes the preparation of common nano porous structures. The hole structure design, particularly the design and preparation of the step hole structure are blank, so that the technical scheme belongs to the innovative technical invention for filling the technical blank.
Disclosure of Invention
Aiming at the problems that most preparation methods in the prior art can only prepare common nano porous silicon structures and can not effectively solve the problem of volume expansion of silicon as a lithium ion battery cathode material, the invention provides nano porous silicon with a step structure, a sintering-etching preparation method and application thereof, and aims to provide the steps of: the structure is prepared, the internal and external pore structures and the porosity of the particles are sequentially increased, the structure can effectively reduce stress accumulation, can provide space required in the volume expansion process, and effectively eliminates or slows down the damage of volume expansion and shrinkage to the silicon cathode structure in the lithium intercalation and lithium deintercalation processes.
The technical scheme adopted by the invention is as follows:
a sintering-etching preparation method of nano porous silicon with a step structure comprises the following steps:
[1] mixing and grinding silicon powder and copper powder in proportion, and sintering the fully ground mixed powder in an inert gas atmosphere to obtain a precursor;
[2] etching the precursor obtained in the step (1) in an oxidizing solution;
[3] and (3) filtering, washing and drying the precursor etched in the step (2) to obtain the nano porous silicon with the step structure.
By adopting the technical scheme, a structure that the particle is sequentially increased from the inside to the outside pore structure and the porosity can be prepared, the structure can effectively reduce stress accumulation, can provide a space required in the volume expansion process, and effectively eliminates or slows down the damage of volume expansion and shrinkage to a silicon cathode structure in the lithium embedding and lithium removing processes.
Preferably, the mixing ratio of the silicon powder to the copper powder is 0.5:1 to 5: 1. and mixing silicon powder and copper powder together for sintering, wherein copper and silicon can form a silicon-copper alloy at high temperature. Controlling the mole ratio of Si to Cu within the scope of the preferred embodiment, the precursor particles thus obtained have the structure: inside a particle, the outer layer of the particle is silicon-copper alloy, the inner part of the particle is silicon, and a transition region exists at the boundary of the silicon and the silicon-copper alloy. When the precursor is etched, more gaps are formed on the outer surface of the particle, the pore diameter is larger, and the porosity inside the particle is smaller and the pore diameter is smaller.
Preferably, the sintering temperature used for sintering is 400-1100 ℃.
Preferably, the solution having oxidizing property in the step [2] is a ferric trichloride solution. The solution with oxidizability can be any oxide capable of oxidizing copper, and in the technical scheme, the solution is preferably ferric trichloride solution.
The invention also provides the cascade structure nano porous silicon prepared by the sintering-etching preparation method of the cascade structure nano porous silicon.
The invention also provides an application method of the gradient-structure nano porous silicon as a lithium ion battery cathode material.
The development of electric automobiles needs the development of energy storage batteries towards high energy density, silicon becomes the most probable next-generation lithium ion battery cathode material with ultrahigh specific energy density, and the gradient-structure nano porous silicon used as the lithium ion battery cathode material can solve the expansion problem of the lithium ion battery cathode material, so that the energy storage batteries can be greatly promoted to be applied in the traffic field.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
the technical scheme of the invention can prepare a structure in which the pore structure and the porosity of the particles are sequentially increased from inside to outside, the structure can effectively reduce stress accumulation, provide a space required in the volume expansion process, and effectively eliminate or slow down the damage of volume expansion and shrinkage to the silicon cathode structure in the lithium intercalation and lithium deintercalation processes.
The development of electric automobiles needs the development of energy storage batteries towards high energy density, silicon becomes the most probable next-generation lithium ion battery cathode material with ultrahigh specific energy density, and the expansion problem of the silicon can greatly promote the application of the energy storage batteries in the traffic field.
In the prior art, a solution for solving the expansion of the silicon material is to coat a layer of porous material (usually porous carbon or polymer) outside the silicon material to form a core-shell structure. By contrast, the material prepared by the scheme is mainly silicon, and the problem of silicon material expansion is solved without adopting a shell layer wrapping method. Therefore, compared with the prior art similar to the prior art, the technical scheme also has the following additional beneficial effects: the preparation method is simple; the proportion of silicon in the material is higher so that higher specific energy density can be achieved.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a flow chart of one embodiment of a sintering-etching method for preparing nano porous silicon with a step structure according to the present invention;
FIG. 2 is an XRD pattern of a precursor prepared by high temperature sintering in example 1 of the present invention;
FIG. 3 is an XRD pattern of the precursor after etching in example 1 of the present invention;
FIG. 4 shows the BET characterization of the precursor after etching in example 1 of the present invention.
Detailed Description
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
The present invention will be described in detail with reference to fig. 1 to 4.
A sintering-etching preparation method of nano porous silicon with a step structure comprises the following steps:
[1] and mixing and grinding the silicon powder and the copper powder according to a proportion, and sintering the fully ground mixed powder in an inert gas atmosphere to obtain a precursor. Preferably, the sintering temperature used for sintering is 400-1100 ℃. Preferably, the mixing ratio of the silicon powder to the copper powder is 0.5:1 to 5: 1. and mixing silicon powder and copper powder together for sintering, wherein copper and silicon can form a silicon-copper alloy at high temperature. According to the literature "tang renzhen, tianrong jade tablet," binary alloy phase diagram and mesophase crystal structure ", the molar ratio of si to cu is controlled within the preferred ranges mentioned above, and the structure of the precursor particles thus obtained is: inside a particle, the outer layer of the particle is silicon-copper alloy, the inner part of the particle is silicon, and a transition region exists at the boundary of the silicon and the silicon-copper alloy.
[2] Etching the precursor obtained in the step (1) in an oxidizing solution; the oxidizing solution can be any oxide capable of oxidizing copper, and is preferably a ferric chloride solution. When the precursor is etched, more gaps are formed on the outer surface of the particle, the pore diameter is larger, and the porosity inside the particle is smaller and the pore diameter is smaller.
[3] And (3) filtering, washing and drying the precursor etched in the step (2) to obtain the nano porous silicon with the step structure. The gradient structure nano porous silicon particles sequentially increase from inside to outside and the porosity, the structure can effectively reduce stress accumulation, provide a space required in the volume expansion process, and effectively eliminate or slow down the damage of volume expansion and shrinkage to a silicon cathode structure in the lithium intercalation and lithium removal processes.
The invention also provides the nano porous silicon with the step structure prepared by the sintering-etching preparation method.
The invention also provides the step structure nano porous silicon used as a lithium ion battery cathode material. The method for preparing the lithium ion battery cathode material from the step-structure nano porous silicon provided by the invention is the same as the method for preparing the lithium ion battery cathode material from the silicon/carbon composite material or the silicon material in the prior art, belongs to the prior art, and is not described herein.
Example 1
In this embodiment, the preferred mode of the specific process parameters is that the molar ratio of the silicon powder to the copper powder is 0.5:1, the sintering temperature is 400-410 ℃. After the precursor is prepared, 2g of the precursor is added into 200ml of ferric trichloride solution with the concentration of 0.1mol/L for etching, and the etching time is 20 min. And filtering, washing and vacuum drying after etching to obtain the nano porous silicon with the step structure.
In this example, XRD characterization of the precursor and the step-structured nanoporous silicon are shown in fig. 2 and fig. 3, respectively.
According to the BET characterization result of FIG. 4, the specific surface area of the stepped nanoporous silicon prepared by the embodiment can reach 76m2In terms of a/g, the pore diameter has two distinct peaks at 3.5nm and 5.5 nm. The surface porosity was proved to be high, and according to the description of the document "tang ren politics, tianrong jade tablet," binary alloy phase diagram and mesophase crystal structure ", the interior of the particles of the precursor is almost pure silicon, so no pores are generated during etching, and thus it can be seen that the structure of the step-structured nanoporous silicon prepared in this example has the characteristic that the pore structure and the porosity of the particles increase from the interior to the exterior in sequence.
Example 2
In this embodiment, the preferred mode of the specific process parameters is that the molar ratio of the silicon powder to the copper powder is 5:1, the sintering temperature is 1090-1100 ℃. After the precursor is prepared, 20g of the precursor is added into 500ml of ferric trichloride solution with the concentration of 0.5mol/L for etching, and the etching time is 40 min. And filtering, washing and vacuum drying after etching to obtain the nano porous silicon with the step structure.
The above-mentioned embodiments only express the specific embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for those skilled in the art, without departing from the technical idea of the present application, several changes and modifications can be made, which are all within the protection scope of the present application.

Claims (4)

1. A sintering-etching preparation method of nano porous silicon with a step structure is characterized by comprising the following steps:
[1] mixing and grinding silicon powder and copper powder in proportion, and sintering the fully ground mixed powder in an inert gas atmosphere to obtain a precursor;
[2] etching the precursor obtained in the step (1) in an oxidizing solution, wherein the oxidizing solution is used for etching copper in the precursor;
[3] filtering, washing and drying the precursor etched in the step (2) to obtain the nano porous silicon with the step structure;
the mixing ratio of the silicon powder to the copper powder is 0.5:1 to 5: 1;
the sintering temperature adopted by the sintering is 400-1100 ℃.
2. The sintering-etching preparation method of the step-structured nanoporous silicon as claimed in claim 1, wherein: and (3) in the step (2), the solution with the oxidability is a ferric trichloride solution.
3. The sintering-etching preparation method of the step-structured nanoporous silicon according to claim 1.
4. The sintering-etching preparation method of the step-structured nanoporous silicon according to claim 1, wherein the prepared step-structured nanoporous silicon is used as a lithium ion battery cathode material.
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CN101740766B (en) * 2008-11-21 2012-07-25 比亚迪股份有限公司 Cathode active material, preparation method thereof and lithium battery using same
KR20120010211A (en) * 2010-07-23 2012-02-02 강원대학교산학협력단 Porous silicon based alloy, method of preparing the same, and negative active material for rechargeable lithium battery and rechargeable lithium battery including the same
CA2829605C (en) * 2013-10-07 2016-06-14 Springpower International Incorporated A method for mass production of silicon nanowires and/or nanobelts, and lithium batteries and anodes using the silicon nanowires and/or nanobelts
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CN104576353A (en) * 2014-12-10 2015-04-29 昆明理工大学 Method for preparing nano-porous silicon from Cu nano-particles by two-step auxiliary etching
CN106629736B (en) * 2016-12-20 2019-04-23 浙江大学 A kind of preparation method of porous silicon powder
CN108493417A (en) * 2018-03-22 2018-09-04 山东大学 A kind of composite material and preparation method of gradient nano porous silicon metal

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