CN119361618A

CN119361618A - Negative electrode active material, preparation method thereof, negative electrode plate and application

Info

Publication number: CN119361618A
Application number: CN202310916260.2A
Authority: CN
Inventors: 吴凯; 史东洋; 邓亚茜; 王羽臻; 吕瑞景; 陈宁; 程志鹏
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-07-24
Filing date: 2023-07-24
Publication date: 2025-01-24

Abstract

The present application relates to a negative electrode active material and a preparation method thereof, a negative electrode plate and application, and belongs to the field of battery technology. The negative electrode active material includes a core and a coating layer that covers at least a portion of the surface of the core, and the core includes porous carbon and nano-silicon and silicon oxide compounds distributed at least in the pores of the porous carbon, and the silicon oxide compounds are at least embedded in the nano-silicon. Compared with the negative electrode plate containing traditional silicon-carbon materials, the negative electrode plate containing the negative electrode active material of the present application has a higher compaction density, which improves the specific capacity and volume energy density of the secondary battery.

Description

Negative electrode active material, preparation method thereof, negative electrode plate and application

Technical Field

The application relates to the technical field of batteries, in particular to a negative electrode active material, a preparation method thereof, a negative electrode plate and application thereof.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

With the rapid development of portable electronic devices and electric automobiles, the demand for secondary batteries with high energy density is increasing, and the development of negative electrode materials with high theoretical specific capacities such as silicon-based materials is being promoted. The silicon-carbon material is one of silicon-based materials, and the compaction density is low so that the volumetric energy density of the silicon-carbon material is still to be improved.

Disclosure of Invention

Based on the above, the application provides a negative electrode active material, a preparation method thereof, a negative electrode plate and application thereof. Compared with the negative electrode plate containing the traditional silicon-carbon material, the negative electrode plate containing the negative electrode active material has higher compaction density, and improves the specific capacity and the volumetric energy density of the secondary battery.

In a first aspect of the present application, there is provided a negative electrode active material comprising an inner core and a coating layer coating at least a part of the surface of the inner core, the inner core comprising porous carbon and at least nano-silicon and a silicon oxygen compound distributed in pores of the porous carbon, the silicon oxygen compound being at least embedded in the nano-silicon.

The silicon oxide in the anode active material enhances the structural strength of porous carbon, improves the compaction density of an anode piece containing the anode active material, can provide an ion path for nano silicon and porous carbon, is embedded in the nano silicon, so that the nano silicon can protect the silicon oxide in multiple directions, the corrosion of the silicon oxide by acid is reduced, the specific surface area of the anode active material is reduced by a coating layer, and the side reaction between an inner core and electrolyte is reduced, thereby improving the specific capacity and the volume energy density of the secondary battery.

In some embodiments, the mass percent of the silicone compound is from 0.02% to 40%, alternatively from 0.02% to 20%, based on the mass of the core.

In some embodiments, the mass percent of the nano-silicon is 20% -62% based on the mass of the core.

In some embodiments, the ratio of the mass of the nano-silicon to the total mass of the porous carbon and the nano-silicon is (0.22-0.67): 1.

In some embodiments, the mass ratio of the nano-silicon to the porous carbon is (0.3-2): 1.

In some embodiments, the nanosilicon has a particle size of from 0.02nm to 40nm.

In some embodiments, the silicon oxygen compound comprises a material having the formula SiO _x, wherein 0< x.ltoreq.2.

In some embodiments, the negative electrode active material has a tap density of 0.4g/cm ³-2g/cm³.

In some embodiments, the specific surface area of the anode active material is 0.005m ²/g-4m²/g.

In some embodiments, the coating layer comprises a carbon material.

In some embodiments, the coating layer is 0.2% -2% by mass based on the mass of the anode active material.

In a second aspect of the present application, there is provided a method for preparing the anode active material according to the first aspect of the present application, comprising the steps of:

Forming the nano silicon and the silicon oxygen compound in the pores of the porous carbon to obtain the inner core;

the cladding layer is formed on at least a portion of the surface of the core.

The preparation method is simple and is easy for large-scale production.

In some embodiments, the step of forming the nano-silicon and the silicon oxygen compound in the pores of the porous carbon to obtain the core comprises:

Performing chemical vapor deposition on the porous carbon by using silane substances and reducing gas;

mixing a product obtained by chemical vapor deposition with a silicon source, a reducing agent and a solvent;

and (5) carrying out reduction treatment on the materials obtained by mixing.

In some embodiments, the porous carbon has a porosity of 40% to 90%.

In some embodiments, the silane species include one or more of monosilane, disilane, tetrafluorosilane, silicon trichloride, and chlorosilane.

In some embodiments, the reducing gas comprises one or more of acetylene, ethylene, and methane.

In some embodiments, the silicon source comprises one or more of ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

In some embodiments, the reducing agent comprises one or more of sucrose and glucose.

In some embodiments, the solvent comprises one or more of ethanol and isopropanol.

In some embodiments, the volume ratio of the silane species to the reducing gas is (0.2-10000): 1.

In some embodiments, the total flow rate of the silane species and the reducing gas is from 100mL/min to 800mL/min.

In some embodiments, the process conditions of the chemical vapor deposition include a deposition temperature of 300 ℃ to 1000 ℃ and a deposition time of 0.2h to 3h.

In some embodiments, the mass ratio of the silicon source to the reducing agent is (1-10): 1.

In some embodiments, the mass ratio of the silicon source to the solvent is (1-10): 1.

In some embodiments, the process conditions of the reduction treatment include a reduction temperature of 400 ℃ to 1000 ℃ and a reduction time of 2 hours to 6 hours.

In a third aspect of the present application, there is provided a negative electrode sheet comprising at least one of the negative electrode active material according to the first aspect of the present application and the negative electrode active material produced by the production method according to the second aspect of the present application.

The negative electrode tab of the present application includes the negative electrode active material provided by the present application, and thus has at least the same advantages as the negative electrode active material.

In some embodiments, the negative electrode sheet has a compacted density of 0.9g/cm ³-1.9g/cm³.

In a fourth aspect of the present application, there is provided a secondary battery comprising the negative electrode tab according to the third aspect of the present application.

The secondary battery of the present application includes the anode active material provided by the present application, and thus has at least the same advantages as the anode active material.

In a fifth aspect of the present application, there is provided an electric device comprising at least one of the anode active material according to the first aspect of the present application, the anode active material produced by the production method according to the second aspect of the present application, the anode tab according to the third aspect of the present application, and the secondary battery according to the fourth aspect of the present application.

The power utilization device of the application comprises the negative electrode active material provided by the application, and therefore has at least the same advantages as the negative electrode active material.

The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the application will be apparent from the description and drawings, and from the claims.

Drawings

For a better description and illustration of embodiments or examples provided by the present application, reference may be made to one or more of the accompanying drawings. Additional details or examples used to describe the drawings should not be construed as limiting the scope of any of the disclosed applications, the presently described embodiments or examples, and the presently understood best mode of carrying out these applications. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:

Fig. 1 is a schematic structural view of a negative electrode active material according to an embodiment of the present application.

FIG. 2 is a flow chart of the preparation of a core according to an embodiment of the present application.

Fig. 3 is a schematic view of a battery cell according to an embodiment of the present application.

Fig. 4 is an exploded view of the battery cell according to an embodiment of the present application shown in fig. 3.

Fig. 5 is a schematic view of a battery module according to an embodiment of the present application.

Fig. 6 is a schematic view of a battery pack according to an embodiment of the present application.

Fig. 7 is an exploded view of the battery pack of the embodiment of the present application shown in fig. 6.

Fig. 8 is a schematic view of an electric device in which a secondary battery according to an embodiment of the present application is used as a power source.

Reference numerals illustrate:

1 battery pack, 2 upper case, 3 lower case, 4 battery module, 5 battery unit, 51 case, 52 electrode assembly, 53 cover plate, 6 electric device, 7 negative electrode active material, 70 inner core, 701 porous carbon, 702 nanometer silicon, 703 silicon oxygen compound and 71 coating layer.

Detailed Description

Hereinafter, some embodiments of the anode active material of the present application, and a preparation method, an anode tab, and an application thereof are described in detail with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

The "range" disclosed herein may be defined in terms of lower and upper limits, with a given range being defined by the selection of a lower limit and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges may be defined in this way as either inclusive or exclusive of the endpoints, any of which may be independently inclusive or exclusive, and any combination may be made, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if minimum range values 1 and 2 are listed, and if maximum range values 3,4, and 5 are also listed, then the following ranges are all contemplated as 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is equivalent to the list of the parameter as, for example, integers of 2,3, 4, 5, 6,7,8,9,10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", the integers 2,3, 4, 5, 6,7,8,9 and 10 are listed.

In the present application, "plural", etc., refer to, unless otherwise specified, an index of 2 or more in number. For example, "one or more" means one kind or two or more kinds.

All embodiments of the application and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment or implementation of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments. Reference herein to "embodiments" is intended to have a similar understanding.

It will be appreciated by those skilled in the art that in the methods of the embodiments or examples, the order of writing the steps is not meant to be a strict order of execution and the detailed order of execution of the steps should be determined by their functions and possible inherent logic. All the steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise specified. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

In the present application, the open technical features or technical solutions described by words such as "contain", "include" and the like are considered to provide both closed features or solutions composed of the listed members and open features or solutions including additional members in addition to the listed members unless otherwise stated. For example, a includes a1, a2, and a3, and may include other members or no additional members, unless otherwise stated, and may be considered as providing features or aspects of "a consists of a1, a2, and a 3" as well as features or aspects of "a includes not only a1, a2, and a3, but also other members". In the present application, a (e.g., B), where B is one non-limiting example of a, is understood not to be limited to B, unless otherwise stated.

In the present application, "optional" refers to the presence or absence of the possibility, i.e., to any one of the two parallel schemes selected from "with" or "without". If multiple "alternatives" occur in a technical solution, if no particular description exists and there is no contradiction or mutual constraint, then each "alternative" is independent.

The silicon-based material is a negative electrode active material having a relatively high theoretical specific capacity, and includes a silicon oxygen material and a silicon carbon material. The silicon-carbon material has higher compaction density, but is not acid-proof and has poor dynamic performance, and the silicon-carbon material has lower compaction density, so that the requirement of people on high energy density of the battery can not be met. How to use the two materials together is important to improve the volume energy density of the secondary battery. Based on the above, the application provides a negative electrode active material, which comprises an inner core and a coating layer at least coating a part of the surface of the inner core, wherein the inner core comprises porous carbon, nano silicon and a silicon oxide which are at least distributed in pores of the porous carbon, the silicon oxide is at least embedded in the nano silicon, the silicon oxide can enhance the structural strength of the porous carbon, so that the compaction density of a negative electrode plate containing the negative electrode active material can be improved, meanwhile, the silicon oxide can provide an ion passage for the nano silicon and the porous carbon, the silicon oxide is embedded in the nano silicon, so that the nano silicon can protect the silicon oxide in multiple directions, the corrosion of the silicon oxide by acid is reduced, the specific surface area of the negative electrode active material can be reduced by the coating layer, and the side reaction between the inner core and an electrolyte is reduced, so that the specific capacity and the volume energy density of a secondary battery are improved.

Negative electrode active material

An embodiment of the present application provides a negative active material, including a core including porous carbon and nano silicon and a silicon oxide compound at least distributed in pores of the porous carbon, and a coating layer coating at least a portion of a surface of the core, the silicon oxide compound being at least embedded in the nano silicon.

In the embodiment, the silicon oxide enhances the structural strength of the porous carbon, improves the compaction density of a negative electrode plate containing the negative electrode active material, can provide an ion path for nano silicon and the porous carbon, is embedded in the nano silicon, so that the nano silicon can protect the silicon oxide in multiple directions, the corrosion of the silicon oxide by acid is reduced, the specific surface area of the negative electrode active material is reduced by the coating layer, and the side reaction between the inner core and the electrolyte is reduced, thereby improving the specific capacity and the volume energy density of the secondary battery.

It should be noted that the negative electrode sheet generally has the highest compacted density, and when the actual compacted density of the negative electrode sheet is higher than the highest compacted density, more broken particles of silicon in the negative electrode sheet occur. In the above embodiment, the structural strength of the anode active material is enhanced by the silicon oxide compound, thereby improving the compacted density of the anode tab containing the anode active material.

Fig. 1 is a view of a negative electrode active material as an example. Referring to fig. 1, the anode active material 7 includes an inner core 70 and a coating layer 71 coating at least a part of the surface of the inner core, the inner core 70 including porous carbon 701 and nano-silicon 702 and a silicon oxygen compound 703 distributed at least in the pores of the porous carbon 701, the silicon oxygen compound 703 being at least embedded in the nano-silicon 702.

In some embodiments, the mass percent of the silicone compound is from 0.02% to 40% based on the mass of the core. By controlling the mass percentage of the silicon oxygen compound within the above range, the specific capacity and the volumetric energy density of the secondary battery can be further improved. It is understood that the mass percent of the silicone compound based on the mass of the core includes, but is not limited to, 0.02%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%. Further, the mass percent of the silicon oxygen compound is 0.02% -20% based on the mass of the core.

In some embodiments, the mass percent of nano-silicon is 20% -62% based on the mass of the core. Thus, the specific capacity and volumetric energy density of the secondary battery can be further improved. And the mass ratio of the silicon oxide to the nano silicon can be controlled within a certain range, so that the secondary battery can exert the volume energy density with higher specific capacity.

The content of the silicon oxide in the inner core can be tested by using an X-ray photoelectron spectroscopy (XPS), for example, a negative electrode plate containing the silicon oxide can be disassembled after being fully charged, then the XPS is tested, the Li-Si chemical bonds and the Si-O chemical bond ratio of the negative electrode plate are compared, so that the relative content of the silicon oxide and the nano silicon is determined, and the content of the nano silicon can be quantitatively tested by using an inductively coupled plasma emission spectrometer (ICP).

In some embodiments, the ratio of the mass of nano-silicon to the total mass of porous carbon and nano-silicon is (0.22-0.67): 1. It is understood that the ratio of the mass of the nano-silicon to the total mass of the porous carbon and the nano-silicon includes, but is not limited to, 0.22:1, 0.25:1, 0.28:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.67:1.

In some embodiments, the mass ratio of nano-silicon to porous carbon is (0.3-2): 1. Controlling the mass ratio of the nano silicon to the porous carbon within the above range can improve the conductivity of the anode active material, thereby improving the stability of the secondary battery in the cycle process. It is understood that the mass ratio of nano-silicon to porous carbon includes, but is not limited to, 0.3:1, 0.5:1, 0.7:1, 1:1, 1.2:1, 1.5:1, 1.7:1, 2:1.

In some embodiments, the nanosilicon has a particle size of 0.02nm to 40nm. The particle size of the nano silicon is controlled to be in the range, so that the active ion transmission path can be shortened, and the rate performance of the secondary battery can be improved. It is understood that the particle size of the nano-silicon includes, but is not limited to, 0.02nm, 0.05nm, 0.1nm, 0.5nm, 2nm, 5nm, 8nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm.

Alternatively, the nano-silicon particle size may be measured by taking a photograph of a cross section of the negative electrode active material using a Transmission Electron Microscope (TEM), or may be measured by using an X-ray diffractometer (XRD), and calculating the nano-silicon particle size using a scherrer equation according to characteristic peaks of nano-silicon therein.

In some embodiments, the silicon oxygen compound includes a material having the formula SiO _x, wherein 0< x.ltoreq.2.

In some embodiments, the tap density of the anode active material is 0.4g/cm ³-2g/cm³. The tap density of the anode active material is controlled within the above range, and the specific capacity and the volumetric energy density of the secondary battery are further improved. It is understood that the tap density of the anode active material includes, but is not limited to ：0.4g/cm³、0.6g/cm³、0.8g/cm³、1g/cm³、1.2g/cm³、1.4g/cm³、1.6g/cm³、1.8g/cm³、2g/cm³.

The tap density of the anode active material is in the meaning known in the art, and can be measured by an instrument and method known in the art, for example, conveniently measured by a tap density meter such as BT-300 type tap density meter.

In some embodiments, the specific surface area of the anode active material is 0.005m ²/g-4m²/g. For example, the specific surface area of the anode active material may be 0.005m²/g、0.05m²/g、0.5m²/g、0.8m²/g、1m²/g、1.5m²/g、2m²/g、2.5m²/g、3m²/g、3.5m²/g or 4m ²/g or the like.

The specific surface area of the anode active material may be tested by a nitrogen adsorption and desorption method, and for example, the BET specific surface area of the material may be measured using a specific surface area analyzer (TRI STARII), which is performed with reference to GB/T19587-2004 standard.

In some embodiments, the coating layer comprises a carbon material. Optionally, the carbon material comprises amorphous carbon.

In some embodiments, the mass percent of the coating layer is 0.2% -2% based on the mass of the anode active material.

Another embodiment of the present application provides a method for preparing the above negative active material, including the steps of:

Forming nano silicon and silicon oxygen compounds in the pores of the porous carbon to obtain a core;

A coating layer is formed on at least a part of the surface of the core.

Thus, the anode active material can be simply prepared, which is beneficial to the mass production of the anode active material.

In some embodiments, the step of forming nano-silicon and silicon oxygen compounds in the pores of the porous carbon to obtain the core comprises:

and (5) carrying out reduction treatment on the materials obtained by mixing.

In the embodiment, the generated nano silicon can permeate into the pores of the porous carbon and finish diffusion and reduction when chemical vapor deposition is carried out, and the generated silicon oxide is filled in the pores of the porous carbon and embedded in the nano silicon and the porous carbon when the mixed materials are subjected to reduction treatment. Thus, the core can be simply prepared.

In some embodiments, in conjunction with fig. 2, the step of forming nano-silicon and silicon oxygen compounds in the pores of the porous carbon to obtain the core comprises:

S10, performing chemical vapor deposition on porous carbon 701 by using silane substances and reducing gas;

s20, mixing the product obtained in the step S10 with a silicon source, a reducing agent and a solvent;

s30, carrying out reduction treatment on the material obtained in the step S20.

In the above embodiment, the porous carbon 701 has micropores and macropores, the step S10 fills the generated nano silicon 702 in the micropores of the porous carbon 701, and the steps S20 and S30 fill the generated silicon oxide in the macropores of the porous carbon 702.

In some embodiments, the step of forming a coating layer on at least a portion of the surface of the inner core includes coating the inner core with a carbon source. Optionally, the carbon source comprises one or more of acetylene and pitch.

In some embodiments, the volume ratio of silane species to reducing gas is (0.2-10000): 1. It is understood that the volume ratio of silane species to reducing gas includes, but is not limited to, 0.2:1, 10:1, 100:1, 500:1, 1000:1, 2000:1, 3000:1, 4000:1, 5000:1, 6000:1, 7000:1, 8000:1, 9000:1, 10000:1.

In some embodiments, the total flow rate of the silane species and the reducing gas is from 100mL/min to 800mL/min. It is understood that the total flow rates of the silane species and the reducing gas include, but are not limited to, 100mL/min, 200mL/min, 300mL/min, 400mL/min, 500mL/min, 600mL/min, 700mL/min, 800mL/min.

In some embodiments, the process conditions for chemical vapor deposition include a deposition temperature of 300 ℃ to 1000 ℃ and a deposition time of 0.2 hours to 3 hours. It is understood that deposition temperatures include, but are not limited to, 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1000 ℃, and deposition times include, but are not limited to, 0.2h, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h.

In some embodiments, the mass ratio of silicon source to reducing agent is (1-10): 1. It is understood that the mass ratio of silicon source to reducing agent includes, but is not limited to, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1.

In some embodiments, the mass ratio of silicon source to solvent is (1-10): 1. It is understood that the mass ratio of silicon source to solvent includes, but is not limited to, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1.

In some embodiments, the process conditions of the reduction treatment include a reduction temperature of 400 ℃ to 1000 ℃ and a reduction time of 2 hours to 6 hours. It is understood that the reduction temperatures include, but are not limited to, 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1000 ℃, and the reduction times include, but are not limited to, 2h, 3h, 4h, 5h, 6h.

Another embodiment of the present application provides a negative electrode tab including at least one of the above-described negative electrode active materials and the negative electrode active materials prepared by the above-described preparation method.

In some embodiments, the negative electrode tab further includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including at least one of the negative electrode active materials described above in the present application and the negative electrode active materials prepared in the above-described preparation method of the present application.

As a non-limiting example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode active material layer is provided on either or both of the two surfaces opposing the anode current collector.

In some embodiments, the negative electrode sheet has a compacted density of 0.9g/cm ³-1.9g/cm³. Thereby, the secondary battery can be further provided with a high volumetric energy density. It should be noted that the negative electrode sheet generally has the highest compacted density, and when the actual compacted density of the negative electrode sheet is higher than the highest compacted density, more broken particles of silicon in the negative electrode sheet occur. The structural strength of the negative electrode active material is enhanced by using the silicon oxide, so that the negative electrode active material is applied to the negative electrode plate, and the compaction density of the negative electrode plate is improved. It will be appreciated that the compacted density of the negative electrode sheet described above includes, but is not limited to ：0.9g/cm³、1g/cm³、1.1g/cm³、1.2g/cm³、1.3g/cm³、1.4g/cm³、1.5g/cm³、1.6g/cm³、1.7g/cm³、1.8g/cm³、1.9g/cm³.

In some embodiments, the anode active material layer may include one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like, in addition to the anode active material of the present application. The silicon-based material may include one or more of a silicon-nitrogen composite and a silicon alloy. The tin-based material may include one or more of elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used.

In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the anode active material layer further optionally includes a binder. The binder may include one or more of Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

In some embodiments, the anode active material layer may further optionally include a conductive agent. The conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the anode active material layer may also optionally include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

In some embodiments, the negative electrode tab may be prepared by dispersing the above-described components for preparing the negative electrode tab, such as a negative electrode active material, a conductive agent, a binder, and any other components, in a solvent (non-limiting example of a solvent, such as deionized water) to form a negative electrode slurry, coating the negative electrode slurry on at least one side surface of a negative electrode current collector, and performing processes such as drying, cold pressing, and the like to obtain the negative electrode tab. The surface of the negative electrode current collector coated with the negative electrode slurry may be a single surface of the negative electrode current collector or may be two surfaces of the negative electrode current collector. The solid content of the negative electrode slurry may be 40wt% to 60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 mPas-10000 mPas. When the negative electrode slurry is coated, the coating unit areal density in dry weight (minus solvent) may be 75g/m ²-220g/m². The compacted density of the negative electrode sheet may be 1.0g/cm ³-1.8g/cm³.

The secondary battery and the power consumption device according to the present application will be described below with reference to the drawings.

In one embodiment of the present application, a secondary battery is provided.

In general, a secondary battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film.

Positive electrode plate

The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material.

As a non-limiting example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.

In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be obtained by forming a metal material on a polymeric material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, and the like. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and the like.

For the positive electrode active material where the Li content varies, the subscript of Li is defined in the formula:

For ternary materials:

li _x(Ni_aCo_bMn_c)_1-dM_dO_2-yA_y, x is 0.2-1.2;

Li _xA_a(Ni_aCo_bMn_c)_1-dM_dO_2-yA_y, x+a is 0.2 to 1.2;

For lithium iron manganese phosphate materials:

1) Li _aMn_1-yB_yP_1-zC_zO_4-nD_n, a is 0-1.1;

2) Li _aA_xMn_1-yB_yP_1-zC_zO_4-nD_n, a+x is 0 to 1.1;

The above definition of x includes the molar content of Li at different charge and discharge states of the battery (typically the battery voltage is between 2V and 5V).

It can be understood that the battery is accompanied by the deintercalation and consumption of lithium (Li) during the charge and discharge processes, and the Li content in the positive electrode sheet is different when the battery is discharged to different states. In the present application, the Li content is the initial state of the material unless otherwise specified in the list of the positive electrode active materials. The positive electrode active material is applied to a positive electrode plate in a battery system, and the content of Li in the positive electrode active material contained in the plate is generally changed after charge and discharge cycles. The content of Li may be measured by a molar content, but is not limited thereto. The "Li content is the initial state of the material", which refers to the state before the positive electrode slurry is fed. It is understood that new materials obtained by suitable modification based on the listed positive electrode active materials are also within the category of positive electrode active materials, the foregoing suitable modification being indicative of acceptable modification modes for the positive electrode active materials, non-limiting examples being coating modification.

In the present application, the content of oxygen (O) is only a theoretical state value, and the molar content of oxygen changes due to lattice oxygen release, and the actual O content floats. The content of O may be measured by molar content, but is not limited thereto.

In some embodiments, the positive electrode active material may employ a positive electrode active material for a battery, which is well known in the art. As a non-limiting example, the positive electrode active material may include one or more of olivine structured lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide (e.g., liCoO ₂), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt aluminum oxide, modified compounds thereof, and the like. Non-limiting examples of olivine structured lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxide may include LiCoO ₂, non-limiting examples of lithium nickel oxide may include LiNiO ₂, non-limiting examples of lithium manganese oxide may include LiMnO ₂、LiMn₂O₄, etc., non-limiting examples of lithium nickel cobalt manganese oxide may include LiNi _1/3Co_1/3Mn_1/3O₂ (also may be abbreviated as NCM ₃₃₃)、LiNi_0.5Co_0.2Mn_0.3O₂ (also may be abbreviated as NCM ₅₂₃)、LiNi_0.5Co_0.25Mn_0.25O₂ (also may be abbreviated as NCM ₂₁₁)、LiNi_0.6Co_0.2Mn_0.2O₂ (also may be abbreviated as NCM ₆₂₂)、LiNi_0.8Co_0.1Mn_0.1O₂ (also may be abbreviated as NCM ₈₁₁)) etc. non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi _0.85Co_0.15Al_0.05O₂.

In some embodiments, the positive electrode active material layer may further optionally include a binder. As non-limiting examples, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymers, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymers, tetrafluoroethylene-hexafluoropropylene copolymers, and fluoroacrylate resins.

In some embodiments, the positive electrode active material layer may further optionally include a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode sheet may be prepared by dispersing the above-described components for preparing a positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, in a solvent to form a positive electrode slurry, coating the positive electrode slurry on at least one side surface of a positive electrode current collector, and performing processes such as drying, cold pressing, and the like to obtain the positive electrode sheet. The type of solvent may be selected from, but is not limited to, any of the foregoing embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The solid content of the positive electrode slurry may be 40wt% to 80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 mPas to 25000 mPas. When the positive electrode slurry is coated, the coating unit area density in dry weight (minus solvent) may be 15mg/cm ²-35mg/cm². The positive electrode sheet may have a compacted density of 3.0g/cm ³-3.6g/cm³, optionally 3.3g/cm ³-3.5g/cm³.

Negative pole piece

The negative electrode piece of the embodiment of the application is adopted.

Electrolyte composition

The electrolyte has the function of conducting ions between the positive pole piece and the negative pole piece. The type of electrolyte is not particularly limited in the present application, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF ₆), lithium tetrafluoroborate (LiBF ₄), lithium perchlorate (LiClO ₄), lithium hexafluoroarsenate (LiAsF ₆), lithium bis-fluorosulfonimide (LiFSI), lithium bis-trifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO ₂F₂), lithium difluorooxalato borate (lidadiob), lithium difluorooxalato phosphate (LiDFOP), and lithium tetrafluorooxalato phosphate (LiTFOP).

In some embodiments, the solvent may include ethylene carbonate (EC,) Propylene carbonate (PC,) Methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl Propyl Carbonate (MPC), ethyl Propyl Carbonate (EPC), ethylene carbonateFluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylcarbonate (TFPC), and the like.

Isolation film

In some embodiments, a separator is further included in the secondary battery. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability can be used.

In some embodiments, the material of the isolation film may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

In some embodiments, the thickness of the separator is 6 μm to 40 μm, alternatively 12 μm to 20 μm.

In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

In some embodiments, the secondary battery may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.

In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, or the like. The exterior package of the secondary battery may also be a pouch type pouch, for example. The material of the soft bag can be plastic, and further, non-limiting examples of the plastic can comprise one or more of polypropylene, polybutylene terephthalate, polybutylene succinate and the like.

The secondary battery includes at least one battery cell therein. The secondary battery may include 1 or more battery cells.

In the present application, unless otherwise indicated, "battery cell" refers to a basic unit capable of achieving mutual conversion of chemical energy and electric energy, and further, generally includes at least a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate.

The shape of the battery cell is not particularly limited in the present application, and may be cylindrical, square or any other shape. For example, fig. 3 is a square-structured battery cell 5 as one example.

In some embodiments, referring to fig. 4, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 can be provided to cover the opening to close the accommodation chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged in the receiving chamber. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 included in the battery cell 5 may be one or more, and one skilled in the art may select according to actual needs.

The secondary battery may be the battery module 4 or the battery pack 1.

The battery module includes at least one battery cell. The number of battery cells included in the battery module may be one or more, and one skilled in the art may select an appropriate number according to the application and capacity of the battery module.

Fig. 5 is a battery module 4 as an example. Referring to fig. 5, in the battery module 4, a plurality of battery cells 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of battery cells 5 may be further fixed by fasteners.

Alternatively, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and one skilled in the art may select an appropriate number according to the application and capacity of the battery pack.

Fig. 6 and 7 are battery packs 1 as an example. Referring to fig. 6 and 7, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

In addition, the application also provides an electric device, which comprises the secondary battery provided by the application. The secondary battery may be used as a power source of an electric device, or may be used as an energy storage unit of an electric device. The powered devices may include, but are not limited to, mobile devices, electric vehicles, electric trains, boats and ships, and satellites, energy storage systems, and the like. The mobile device may be, for example, a cellular phone, a notebook computer, etc., and the electric vehicle may be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited thereto.

As the electric device, a secondary battery may be selected according to its use requirement.

Fig. 8 is an electrical device 6 as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. In order to meet the high power and high energy density requirements of the secondary battery by the power consumption device, a battery pack or a battery module may be employed.

As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.

Hereinafter, embodiments of the present application are described. The following examples are illustrative only and are not to be construed as limiting the application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

(1) Preparation of negative electrode active Material

(1.1) Mixing high-purity monosilane and acetylene according to the volume ratio of 100:1, and then sending the mixture into a reaction system in which porous carbon (the porosity is 78%) is placed, so that nano silicon permeates into the pores of the porous carbon and completes diffusion and reduction, the total flow rate of the high-purity monosilane and the acetylene is 400mL/min, the reaction temperature is 500 ℃, and the reaction time is 30min;

(1.2) mixing the product A obtained in the step (1.1) with a mixed solution in a mass ratio of 1:1, and stirring for 2 hours, wherein the mixed solution is formed by ethyl orthosilicate, sucrose and ethanol, the mass ratio of the ethyl orthosilicate to the sucrose is 5:1, and the mass ratio of the ethyl orthosilicate to the ethanol is 3:1;

(1.3) washing and centrifuging the product B obtained in the step (1.2), and reducing the precipitate obtained by centrifugation for 4 hours under an inert gas atmosphere, wherein the flow rate of the inert gas is 400mL/min, and the reduction temperature is 600 ℃;

(1.4) introducing acetylene into the reactor to carry out carbon coating treatment on the product obtained in the step (1.3), wherein the volume ratio of the acetylene to the inert gas is 1:100, and the total flow rate of the acetylene to the inert gas is 400mL/min.

(2) Preparation of negative electrode sheet

Adding a negative electrode active material (the negative electrode active material prepared in the step (1)), a conductive agent acetylene black, a thickener sodium carboxymethylcellulose (CMC-Na) and a binder styrene-butadiene rubber (SBR) into water according to a mass ratio of 96:2:1:1, uniformly mixing to prepare a negative electrode slurry, uniformly coating the negative electrode slurry on the surfaces of both sides of a negative electrode current collector copper foil, drying at 85 ℃, and then cold pressing to prepare a negative electrode plate, wherein the compaction density of the negative electrode plate is 1.5g/cm ³.

(3) Preparation of positive electrode sheet

Uniformly mixing an anode active material nickel cobalt manganese ternary material (NCM 811), a conductive agent acetylene black and a binder polyvinylidene fluoride (PVDF) according to a mass ratio of 97:2:1, adding the mixture into a solvent NMP to prepare anode slurry, uniformly coating the anode slurry on the surfaces of both sides of an anode current collector aluminum foil, drying at 85 ℃, cold pressing, die cutting and slitting to prepare an anode plate.

(4) Preparation of a separator film

The preparation method comprises the steps of taking a polyethylene microporous film as a porous isolating film substrate, uniformly mixing inorganic aluminum trioxide powder, polyvinylpyrrolidone and an acetone solvent according to a weight ratio of 3:1.5:5.5 to prepare slurry, coating the slurry on one surface of the substrate, and drying to obtain the isolating film.

(5) Preparation of electrolyte

Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and methyl ethyl carbonate (the volume ratio of the ethylene carbonate to the dimethyl carbonate to the methyl ethyl carbonate is 1:2:1), so that an electrolyte is obtained.

(6) Preparation of lithium ion batteries

And winding the positive pole piece, the negative pole piece and the isolating film to obtain a bare cell, and then performing procedures such as packaging, liquid injection, formation, exhaust and the like to obtain the lithium ion battery, wherein the capacity of the negative pole piece and the capacity of the positive pole piece of the battery are 1 (namely N/P=1), and the rated capacity of the battery is 100Ah.

Examples 2 to 10

The essential difference is that the parameters as described in tables 1-2 are different, and the negative electrode active material is replaced with the negative electrode active material prepared in step (1) of the corresponding example when the negative electrode tab is prepared in step (2).

Comparative example 1

The procedure is substantially as in example 1, except that step (1.2) and step (1.3) are omitted.

Comparative example 2

The procedure is substantially as in example 2, except that step (1.2) and step (1.3) are omitted.

Comparative example 3

Substantially the same as in example 9, except that the step (1.2) and the step (1.3) were omitted.

Performance testing

(1) Compaction density of negative electrode sheet

The total thickness of the pole piece is measured by using a vernier caliper, and the thickness of the current collector is subtracted to calculate the thickness of the coating. The compacted density of the pole piece can be calculated according to the two parameters of the coating surface density and the coating thickness.

(2) Specific capacity of battery

At 25 ℃, the lithium ion battery is charged to 4.3V at a constant current of 0.33C rate, then charged to a constant voltage of 0.05C current, kept stand for 5min, and then discharged to 2.5V at a constant current of 0.33C rate, and the discharge capacity at that time is recorded, namely the discharge capacity of 0.33C, and the mass of the discharge capacity of 0.33C divided by the mass of the negative electrode active material is the discharge specific capacity of 0.33C.

(3) Rate capability of battery

And (3) at 25 ℃, charging the lithium ion battery to 4.3V at a constant current of 0.33 ℃, charging to a current of 0.05C at a constant voltage, standing for 5min, discharging to 2.5V at a constant current of 0.33C, recording the discharge capacity at the moment, namely the discharge capacity of 0.33C, standing for 30min, charging the lithium ion battery to 4.3V at a constant current of 1C, charging to a current of 0.05C at a constant voltage, standing for 5min, discharging to 2.5V at a constant current of 1C, and recording the discharge capacity at the moment, namely the discharge capacity of 1C.

The rate performance of the battery was 1C/0.33C (%) =1c discharge capacity/0.33C discharge capacity×100%.

TABLE 1 product parameters of negative electrode active materials and negative electrode sheets

Table 2 preparation parameters of anode active materials

Table 3 battery performance

From the observations of tables 1 to 3, and comparing example 1, examples 3 to 8, and example 10 with comparative example 1, and comparing example 2 with comparative example 2, and comparing example 9 with comparative example 3, it is clear that the specific capacity of the secondary battery is low in the case where only nano-silicon is present in the negative electrode active material. The cores of examples 1-10 contain a silicon oxide, and the silicon oxide is at least embedded in the negative electrode active material of the nano silicon, so that the specific capacity of the secondary battery is effectively improved, and the volumetric energy density of the secondary battery is further improved.

The foregoing description of various embodiments is intended to highlight differences between the various embodiments, which may be the same or similar to each other by reference, and is not repeated herein for the sake of brevity.

The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.

Claims

1. A negative electrode active material characterized by comprising a core and a coating layer coating at least a part of the surface of the core, wherein the core comprises porous carbon, and nano silicon and a silicon oxygen compound at least distributed in pores of the porous carbon, and the silicon oxygen compound is at least embedded in the nano silicon.

2. The anode active material according to claim 1, wherein the anode active material has one or more of the following features:

(1a) The mass percentage of the silicon oxygen compound is 0.02-40%, optionally 0.02-20% based on the mass of the inner core;

(1b) Based on the mass of the inner core, the mass percentage of the nano silicon is 20% -62%.

3. The anode active material according to claim 1 or2, characterized in that the anode active material has one or more of the following features:

(2a) The ratio of the mass of the nano-silicon to the total mass of the porous carbon and the nano-silicon is (0.22-0.67): 1;

(2b) The mass ratio of the nano silicon to the porous carbon is (0.3-2) 1.

4. The anode active material according to claim 1 or 2, wherein the nano-silicon has a particle diameter of 0.02nm to 40nm.

5. The anode active material according to claim 1 or 2, wherein the silicon oxide compound comprises a material having a chemical formula of SiO _x, wherein 0< x.ltoreq.2.

6. The anode active material according to claim 1 or2, characterized in that the anode active material has one or more of the following features:

(3a) The tap density of the negative electrode active material is 0.4g/cm ³-2g/cm³;

(3b) The specific surface area of the negative electrode active material was 0.005m ²/g-4m²/g.

7. The anode active material according to claim 1 or 2, wherein the coating layer includes a carbon material;

Optionally, the coating layer is 0.2% -2% by mass based on the mass of the anode active material.

8. The method for producing a negative electrode active material according to any one of claims 1 to 7, characterized by comprising the steps of:

the cladding layer is formed on at least a portion of the surface of the core.

9. The method of producing according to claim 8, wherein the step of forming the nano-silicon and the silicon oxygen compound in the pores of the porous carbon to obtain the core comprises:

Reducing the mixed material;

Optionally, the porous carbon has a porosity of 40% -90%.

10. The method of preparation of claim 9, wherein the method of preparation satisfies one or more of the following conditions:

(4a) The silane substance comprises one or more of monosilane, disilane, tetrafluorosilane, silicon trichloride and chlorosilane;

(4b) The reducing gas comprises one or more of acetylene, ethylene and methane;

(4c) The silicon source comprises one or more of ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate;

(4d) The reducing agent comprises one or more of sucrose and glucose;

(4e) The solvent includes one or more of ethanol and isopropanol;

(4f) The volume ratio of the silane substance to the reducing gas is (0.2-10000) 1;

(4g) The total flow rate of the silane substance and the reducing gas is 100mL/min-800mL/min;

(4h) The process conditions of the chemical vapor deposition comprise deposition temperature of 300-1000 ℃ and deposition time of 0.2-3 h;

(4i) The mass ratio of the silicon source to the reducing agent is (1-10): 1;

(4j) The mass ratio of the silicon source to the solvent is (1-10): 1;

(4k) The technological conditions of the reduction treatment comprise a reduction temperature of 400-1000 ℃ and a reduction time of 2-6 h.

11. A negative electrode sheet comprising at least one of the negative electrode active material according to any one of claims 1 to 7 and the negative electrode active material produced by the production method according to any one of claims 8 to 10;

optionally, the compacted density of the negative electrode sheet is 0.9g/cm ³-1.9g/cm³.

12. A secondary battery comprising the negative electrode tab of claim 11.

13. An electric device comprising at least one of the negative electrode active material according to any one of claims 1 to 7, the negative electrode active material produced by the production method according to any one of claims 8 to 10, the negative electrode tab according to claim 11, and the secondary battery according to claim 12.