CN109599551A

CN109599551A - A kind of doping type multi-layer core-shell silicon based composite material and preparation method thereof for lithium ion battery

Info

Publication number: CN109599551A
Application number: CN201811627828.4A
Authority: CN
Inventors: 查道松; 罗姝; 汪芳; 李喆; 王岑
Original assignee: Ann Price (nanjing) Co Ltd
Current assignee: Boselis Hefei Co ltd; Bosellis Nanjing Co ltd
Priority date: 2018-12-28
Filing date: 2018-12-28
Publication date: 2019-04-09
Anticipated expiration: 2038-12-28
Also published as: CN109599551B

Abstract

The doping type multi-layer core-shell silicon based composite material and preparation method thereof that the present invention relates to a kind of for lithium ion battery, the material is other than it must adulterate Li element, at least also doped with a kind of nonmetalloid and a kind of metallic element, its structure is using the silicon oxide compound particle with element doping as kernel, and the multilayer complex films closely coated using inner core particles surface is shells；It include evenly dispersed simple substance nano silicon particles in the inner core particles, wherein the content of doped chemical gradually decreases from outside to inside and without sharp interface, while inner core particles surface is due to doping insertion one layer of fine and close lithium silicate compound of formation of elemental lithium；The multilayer complex films are for carbon film layer and by carbon film layer and the compound doping type composite film formed of other elements component.There are the electrochemical properties such as capacity height, good rate capability, coulombic efficiency height, good cycle, expansion rate be low when for negative electrode of lithium ion battery.

Description

A kind of doping type multi-layer core-shell silicon based composite material and its system for lithium ion battery Preparation Method

Technical field

The present invention relates to field of lithium ion battery, and in particular to a kind of doping type multi-layer core-shell silicon for lithium ion battery Based composites and preparation method thereof.

Background technique

As one of energy storage device most with prospects at present, lithium ion battery is high by its voltage, self-discharge rate is low, Memory-less effect, it is light-weight, small in size many advantages, such as be concerned, and be widely used in portable electronic product and electricity In electrical automobile.It is constantly progressive with the improvement of living standards with technology, people's various performances all for lithium ion battery, such as Higher requirements are also raised for capacity, energy density, high rate performance and cycle life etc..

Application graphite cathode material the most mature at present, theoretical capacity limited (372mAh/g) and actual capacity is close Exploitation completely, limits further increasing for lithium ion battery energy density.Compared to graphite, silicium cathode material is aobvious by it The high capacity advantage of work, the research and development focus being increasingly becoming in field in recent years, and start gradually to research and develop from laboratory and move towards Commercial applications.In silicium cathode material, the theoretical capacity of simple substance silicon materials is high, and (embedding lithium state is Li at room temperature₁₅Si₄, theory appearance Measure about 3600mAh/g) but its volume expansion is huge and cycle performance is bad；Although silicon oxide compound theoretical capacity is relatively low (about 1700mAh/g), but its expansion rate and cyclical stability are with the obvious advantage, and industrialize compared to being easier to realize for elemental silicon Using.Nevertheless, silicon oxide compound be applied to lithium ion battery in initial charge when can consume lithium generate lithium metasilicate and The substances such as lithia, in electric discharge, lithium ion therein can not be deviate from again.This make its be generally faced with for the first time coulombic efficiency compared with The bottleneck of low (theoretical efficiency is about 70%), to limit the further promotion of full battery energy density.In addition, silicon oxidation is closed The ion and electronic conductivity of object are usually lower, react its de- lithium in lithium ion battery first run charge and discharge process and embedding lithium And it is insufficient, cause in further battery cyclic process that coulombic efficiency is lower, energy density is not high under big multiplying power and circulation conservation rate It is bad.For the above problem of silicon oxide compound, scientific research personnel by nanosizing, with carbon material is compound, Heteroatom doping, pre- embedding Many means such as lithium make improvements.

Application publication number is that the Chinese patent literature of CN105958036A discloses a kind of double-layer carbon coated Si negative electrode material, It is obtained by silicon powder by carbon coating twice.The preparation method of the material includes: to carry out silicon powder after solution dispersion with first Carbon coating layer and dispersing agent disperse together；Solvent is removed, obtained solid material is subjected to high temperature cabonization processing, obtains primary carbon packet Cover silicium cathode material；Primary carbon coating silicon materials are distributed to the second carbon coating material by the dispersion liquid for preparing the second carbon encapsulated material In the dispersion liquid of material, then removes solvent and carry out after baking and obtain secondary carbon coating silicium cathode material.What the method was selected It is the silicon powder of ball mill crushing, silicon particle size is far longer than the silicon nanoparticle generated in silicon oxide compound by disproportionated reaction, Therefore volume expansion/blockage effect of silicon particle is obvious in battery charge and discharge process；In addition, although the material passes through two layers Carbon coating improves the electric conductivity of system, but the intrinsic conductivity of kernel silicon particle is not improved, therefore for institute The promotion for obtaining the high-speed electrical transmission and its high rate performance of material system is not obvious.

Application publication number is that the Chinese patent literature of CN108172775A discloses a kind of phosphorous doped silicon carbon negative pole material, By being sintered after phosphorus doping nano silicon material and graphite and organic carbon source mist projection granulating.The preparation method of the material includes: Spraying dry then progress mist projection granulating, obtains phosphorus after once sintered and mixes after nano silicon material is dispersed in phosphoric acid solution Miscellaneous nano silicon material；Gained phosphorus doping nano silicon material is obtained with graphite and organic carbon source by spray drying and double sintering The phosphorous doped silicon carbon negative pole material.The silicon particle size (generally higher than 100nm) that the method is selected is aoxidized much larger than silicon Close object in disproportionated reaction generate silicon nanoparticle (generally less than 30nm), therefore in battery charge and discharge process silicon particle body Product expansion/blockage effect is obvious；Meanwhile the Si-C composite material selects spray drying and later period sintering to obtain, the method Although easy, the firmness combined between obtained carbon coating layer self-strength and silicon particle and graphite is not high, It is not sufficient enough to reply silicon particle huge volume expansion/blockage effect in charge and discharge process.In conclusion the silicon substrate is multiple The long circulating stability of condensation material is difficult to be guaranteed.In addition, using phosphoric acid as dopant, in later period high-temperature heat treatment It needs strictly to manage in the process, is easy to generate the inflammable by-products of high poisons such as pyrophosphoric acid, metaphosphoric acid or white phosphorus, be unfavorable for extensive It promotes.

Application publication number is that the Chinese patent literature of CN107240693A discloses a kind of phosphorous doped silicon-graphite composite wood Material comprising the N-type silicon and graphite of phosphorus doping.The preparation method of the material includes: that crystalline silicon powder and red phosphorus powder exist Ball milling is carried out under protective atmosphere, obtains phosphorous doped silicon；Phosphorous doped silicon and graphite are subjected to ball milling under protective atmosphere, obtained Phosphorous doped silicon-graphite composite material.Silicon particle major part size in the material is between 0.1 μm~0.5 μm, is much larger than The silicon nanoparticle generated in silicon oxide compound by disproportionated reaction, therefore the volume of silicon particle is swollen in battery charge and discharge process Swollen/blockage effect is obvious；In addition, being difficult to realize carbon material for silicon particle by the obtained Si-C composite material of ball-milling method Intact cladding.Therefore, in water system homogenization process, exposed nano silicon particles can contact with water and air-generating reaction occurs, thus The problems such as causing loss and the bad coating quality of active silicon materials.In addition, in later cycles charge and discharge process, with electrolyte The silicon particle directly contacted can also occur significantly directive property expansion and rupture and constantly formed SEI film, so as to cause its circulation Performance is bad.

Application publication number is that the Chinese patent literature of CN103400971A discloses a kind of silicon based composite material, comprising: silicon The mixture of particle, silicate and optional carbon, silicate and optional carbon forms blocks, and silicon particle is dispersed in blocks In.Preparation method includes: to be distributed to silicon particle, silicate and optional carbon to be formed in dehydrated alcohol and/or deionized water to hang Supernatant liquid is heated and is stirred until flashing to paste；It dries, be ground up, sieved later, be heat-treated in an inert atmosphere, grinding, mistake Sieve obtains silicon based composite material.The silicon particle size that the method is selected is received much larger than what disproportionated reaction in silicon oxide compound generated Rice silicon particle, therefore volume expansion/blockage effect of silicon particle is obvious in battery charge and discharge process；In addition, in the method Silicon particle dispersibility be also not so good as the nano-silicon that disproportionated reaction in silicon oxide compound generates, the non-uniform dispersion of silicon particle can also be led Cause the material internal stress distribution in battery charge and discharge process uneven, so as to cause material granule rupture；Furthermore in the material The interface stability of silicon particle and lithium metasilicate is not as good as the elementary silicon/silicic acid generated after disproportionation in silicon oxide compound and prelithiation reaction Lithium compound system more easily leads to material granule rupture in battery charge and discharge process.In conclusion the silicon based composite material Cyclical stability is difficult to be guaranteed.

Therefore, existing silicon based anode material have capacity is low, coulombic efficiency is low, high rate performance is bad, cyclical stability is poor, The problems such as preparation process is complicated dangerous and incompatible with the aqueous homogenate system that generally uses now, it is difficult to realize in lithium ion Commercial applications in battery are the technical problems of fields.

Summary of the invention

The purpose of the present invention is be directed to current silicon based anode material existing coulomb for the first time when being applied to lithium ion battery The technologies short slabs such as low efficiency, high rate performance are poor, cycle life is short provide a kind of doping type multi-layer core-shell for lithium ion battery Silicon based composite material and its can prepare with scale efficient construction method.

To achieve the above object, present invention provide the technical scheme that

A kind of doping type multi-layer core-shell silicon based composite material for lithium ion battery, in addition to must adulterate Li element it Outside, at least also doped with a kind of nonmetalloid and a kind of metallic element；The doping type multi-layer core-shell silicon based composite material knot Structure be using the silicon oxide compound particle with element doping as kernel, be with the multilayer complex films that inner core particles surface closely coats Shell；In the inner core particles include evenly dispersed simple substance nano silicon particles, wherein the content of doped chemical from outside to inside by It gradually reduces and without sharp interface, while inner core particles surface is due to one layer of fine and close lithium metasilicate system of doping insertion formation of elemental lithium Compound；The multilayer complex films are for carbon film layer and by carbon film layer and the compound doping type composite membrane formed of other elements component Layer；The doped chemical is selected from N, S, P, B, Mg, Al, Cu, Mn, Ca, one of Zn or a variety of, wherein metal-doped element is deposited It is in shell film layer；

The median particle diameter of the doping type multi-layer core-shell silicon based composite material is between 0.3-30 μm, wherein inner core particles Median particle diameter is between 0.3-25 μm, is distributed in the median particle diameter of the simple substance nano silicon particles in kernel silicon oxide compound particle Between 0.1-50nm；Inner core particles outer cladding MULTILAYER COMPOSITE thicknesses of layers between 0.005-10 μm；

In the inner core particles, silicon content 49.9-79.9wt%, oxygen element content 20-50wt%, doping member Cellulose content is 0.01-10%, and silicon, oxygen, doped chemical equal size summation are 100%；The multilayer complex films and silicon oxide compound The weight ratio of inner core particles is 0.01:100-25:100, and in the doping type composite film, element doping amount is in 0.01-5% Between；

The preparation of the doping type multi-layer core-shell silicon based composite material for lithium ion battery is also disclosed in the present invention Method, comprising the following steps:

(1) element doping is directly carried out to silicon oxide compound particle, obtains doping type silicon oxide compound particle；

(2) using doping type silicon oxide compound obtained in step (1) as kernel, in its coated with carbon film layer, then Carry out broken and sub-sieve；

(3) step (2) resulting materials are uniformly mixed with the precursor species containing doped metallic elements, then non-oxygen Heat treatment doping is carried out in the property changed atmosphere, and carries out broken and sub-sieve；

(4) using step (3) resulting materials as kernel, one layer of element doping type carbon film is uniformly coated again on its surface, with After carry out broken and sub-sieve；

(5) step (4) resulting materials are uniformly mixed with lithium-containing compound powder, and is heated in nonoxidizing atmosphere Processing, makes doped chemical in elemental lithium and body phase further diffuse into silicon oxide compound particle, subsequently breaks up and sub-sieve, Finally obtain doping type multi-layer core-shell silicon based composite material；

In above-mentioned steps, can step (3) (4) (5) be carried out with modulation order or synchronous implementation.

In step (1):

Silicon and oxygen element stoichiometric ratio in the silicon oxide compound particle are 1:0.5-1:1.5, median particle size range Between 0.1-20 μm；

The element doping that directly carries out to silicon oxide particles passes through high temperature vapor deposition, high temperature solid-phase sintering, spraying One or more of the methods of dry or ball milling doping combination is realized；

Instrument used by the doping method is CVD furnace, tube furnace, atmosphere batch-type furnace, ball mill or spray dryer Deng one or more of combination realize；

The doped chemical is N, P, B, one or more of elements such as S, F；

The dopant is the gas or solid below containing one or more of doped chemicals, such as ammonia, hydrogen phosphide, red Phosphorus, ammonium hypophosphite, ammonium dihydrogen phosphate, diboron trioxide, boric acid, hydrogen sulfide, thiocarbamide, thioacetamide, ammonium fluoride；

The atmosphere used in doping is the combination of one or more of nitrogen, argon gas, hydrogen, ammonia, hydrogen phosphide etc..

In step (2):

The carbon film layer is directly obtained by way of chemical vapor deposition, or by carrying out carbon matrix precursor cladding in advance The mode for carrying out high-temperature heat treatment carbonization in non-oxidizing atmosphere again obtains；

The method for coating of the carbon matrix precursor is solid phase method or liquid phase method, coat the instrument that uses for mechanical fusion machine, Mechanical agitator, VC mixing machine, cladding kettle, hydrothermal reaction kettle, spray drying, any one in sand mill or high speed disperser Or several combinations, the solvent that when cladding selects are water, methanol, ethyl alcohol, ethylene glycol, isopropanol, n-butanol, acetone, N- methyl pyrrole Pyrrolidone, espeleton, tetrahydrofuran, benzene,toluene,xylene, N,N-dimethylformamide, DMAC N,N' dimethyl acetamide, three The combination of one or more of chloromethanes etc.；The additive selected when cladding is dilute hydrochloric acid, p-methyl benzenesulfonic acid, ammonium persulfate, mistake The combination of one or more of hydrogen oxide, polyvinylpyrrolidone, lauryl sodium sulfate, neopelex etc.；

The carbon matrix precursor is asphalt, coal tar pitch, polyvinyl alcohol, epoxy resin, polyacrylonitrile, polymethylacrylic acid One of methyl esters, aniline, pyrroles, thiophene, glucose, sucrose, polyacrylic acid etc.；

The heat treatment carbonization device therefor is rotary furnace, roller kilns, Electric heat oven, pushed bat kiln, tube furnace or atmosphere box Any one in formula furnace etc.；

The temperature of the high-temperature heat treatment carbonization is 550-1100 DEG C, and heating rate is between 2-50 DEG C/min, heat preservation Time is 1-24 hours；

The nonoxidizing atmosphere is provided by following at least one gases: hydrogen, nitrogen, argon gas or helium；

The break process is using any one in turbine type crushing machine, ball mill, airslide disintegrating mill；

The sub-sieve is using any one in vibrating sieving machine, gas flow sizing machine.

In step (3):

The doped metallic elements are Ca, Mg, Al, Zn, Cu, Mn, Zr, one or more of Fe combination, the forerunner Body substance is metal salt, metal oxide, metal hydroxides or the metal hydride of doped metallic elements；

Mixed method includes solid phase mixing or liquid phase mixing, using mechanical stirring, sand mill, ball mill, spray drying, VC The combination of one or more of mixing machine etc. is realized；

The solvent used in liquid phase mixed process include water, methanol, ethyl alcohol, isopropanol, acetone, N-Methyl pyrrolidone, The combination of one or more of ethyl acetate etc.；

The additive of selection involved in mixed process includes sucrose, glucose, poly- acetimide, polyacrylonitrile, polypropylene The combination of one or more of acid, polyvinylpyrrolidone, lauryl sodium sulfate, neopelex etc.；

The heat treatment doping device therefor is in roller kilns, rotary furnace, pushed bat kiln, atmosphere batch-type furnace or tube furnace etc. Any one；

The heat treatment doping temperature is 700-1200 DEG C, and between 2-50 DEG C/min, soaking time is heating rate 0.5-12 hours；

The nonoxidizing atmosphere is provided by following at least one gases: nitrogen, hydrogen, argon gas or helium；

In step (4):

The element doping type carbon film obtains in the following manner: before selecting self-framework to contain heteroatomic organic carbon It drives body to be coated, be then heat-treated in non-oxidizing atmosphere, presoma realizes heteroatomic original position while carbonization Doping；Or coat dopant together after mixing with carbon matrix precursor, hot place is then carried out in non-oxidizing atmosphere The element doping to carbon film layer is realized while reason carbonization；Or it is coated in carbon film layer presoma and carries out heat treated carbon completion Carry out element doping again afterwards；

The carbon matrix precursor be asphalt, coal tar pitch, polyvinyl alcohol, epoxy resin, polyacrylonitrile, poly- acetimide, One of polymethyl methacrylate, aniline, pyrroles, thiophene, glucose, sucrose, polyacrylic acid etc.；

The dopant be urea, melamine, dicyanodiamine, red phosphorus, ammonium hypophosphite, boric acid, ammonia, hydrogen phosphide, One of hydrogen sulfide etc.；

The temperature of the heat treatment carbonization is 600-1000 DEG C, and heating rate is between 2-50 DEG C/min, soaking time It is 0.5-12 hours；

In step (5):

The lithium-containing compound powder is the reproducibility compound containing lithium；

The maximum particle diameter of the lithium-containing compound powder is less than or equal to 60 μm；

The grinding mode of the lithium-containing compound powder is mortar grinder, ball mill, turbine type crushing machine, airslide disintegrating mill In any one；

Mixed method uses high speed disperser, high-speed stirred mill, ball mill, cone-type mixer, mixing screw, stirring-type Any one in mixing machine or VC mixing machine；

The heat treatment device therefor is any in rotary furnace, roller kilns, pushed bat kiln, tube furnace or atmosphere batch-type furnace etc. It is a kind of；

The temperature of the heat treatment is 500-1000 DEG C, and between 2-50 DEG C/min, soaking time is heating rate 0.5-15 hours；

The nonoxidizing atmosphere is provided by following at least one gases: hydrogen, nitrogen, argon gas or helium.

The present invention is also protected comprising the doping type multi-layer core-shell silicon based composite material negative electrode of lithium ion battery, and is used The lithium ion battery of negative electrode of lithium ion battery preparation.

Compared with prior art, the beneficial effects of the present invention are:

1. being different from obtaining silicon particle, kernel silicon oxide compound in the present invention by conventional massive material breaking method Nano silicon particles contained by grain are formed by disproportionated reaction " from bottom to top ", and size may be significantly smaller, therefore can be significant Alleviate the bulk effect generated during removal lithium embedded repeatedly.In addition, the nano-silicon in inner core particles is evenly dispersed and is fixed on In silicon oxide compound matrix, described matrix can effectively inhibit and buffer the expansion of nano silicon particles, while can also effectively hinder Only silicon particle in charge and discharge process due to gradually melt and at larger-sized particle caused by expansion aggravation and activated silica Partial failure.

2. conventional silicon oxide compound material is usually because electric conductivity is poor and is not enough to the electrode system reality that support phase is answered Existing swift electron transmission and high current charge-discharge, i.e. high rate performance are poor.By to kernel silicon oxide compound particle in the present invention Direct element doping is carried out, the native electronic conductivity of silicon oxide compound particle can be promoted, effectively not only so as to improve gained The high rate performance of material, and the strength covalent bond formed between the carbon film layer of the hetero atom and subsequent cladding adulterated can have Effect promotes the structural stability of carbon film coated layer, promotes material electric conductivity to reach reinforcement and inhibits nano silicon particles volume swollen Swollen effect.

3. carbon coating silicon based anode material common at present is usually single layer carbon film coated, it is typically easy to carbon film layer packet occur Cover not exclusively or combine unstable problem and the wherein exposed caused subsequent a series of problems of inner core particles.Therefore, Metallic element doping and secondary doping type carbon film layer cladding are pointedly successively introduced in the present invention.The metallic element of doping is big It is mostly dispersed in the carbon film layer surface of cladding for the first time in the form of superfine oxide nano particle, acts not only as being anchored Point, which reaches, effectively to be inhibited to be also used as active site due to the carbon film coated layer rupture that internal layer silicon particle expands and occurs to promote Into the firm cladding of subsequent doping type carbon-coating.Then, the close cladding of doping type carbon film layer further can not only be alleviated and press down Bulk effect of the nano-silicon in charge and discharge process in inner core particles processed, can also be obviously improved resulting silicon based composite material Electric conductivity, to further improve high-velocity electrons conducting power and multiplying power of the resulting materials when being applied to negative electrode of lithium ion battery Performance.

4. in order to further alleviate the Volumetric expansion of traditional silicon oxide compound material, while effectively promoting resulting materials Coulombic efficiency for the first time, the present invention construct multilayer coating structure core-shell structure on the basis of doping be embedded in a large amount of lithium atom. Wherein, elemental lithium content shows the concentration gradient successively decreased step by step from outside to inside, and after entering kernel silicon oxide compound particle Lithium silicate compound is formed with oxygen element therein and element silicon, this makes oxygen element therein will not be in lithium intercalation In continuously form the compounds such as lithium metasilicate or lithia, significantly reduce the lithium that resulting materials occur in first charge-discharge Ion irreversible loss effectively promotes for the first time coulombic efficiency of the material in lithium ion battery.In addition, the material internal The lithium atom being embedded in advance in silicon oxide compound particle keeps the lithium ion of its required insertion under same de- lithium capacity less, Thus there is lower particle expansion rate and lower battery pole piece expansion rate and cell expansion rate, to be conducive to cathode material The stable structure for expecting particle, cathode pole piece and battery, that is, be conducive to the cyclical stability of battery.

Air-generating reaction occurs and causes to live 5. conventional silicon nano material would generally contact in water system homogenization process with water Property silicon materials loss, and multi-layer core-shell structure constructed in the present invention can adequately protect the nano-silicon in its inner core particles not It is contacted with extraneous aqueous slurry, to solve the problems, such as that homogenate produces gas；Outer layer intact multilayer coating structure film and kernel The fine and close silicate compound that particle surface is formed has good water resistance, can effectively inhibit the PH liter of aqueous slurry Height, while will not influence the rheological equationm of state and stability of slurry, therefore effectively prevent in coating process because producing gas, slurry rheology Property and stability deteriorate caused by the pole pieces quality problems such as pole piece pin hole, pit, uneven, the bonding difference of surface density.

6. when being applied to lithium ion battery, in the fine and close silicon that constructed multilayer coating structure and inner core particles surface are formed Under the synergistic effect of hydrochlorate based compound, the nano silicon particles inside resulting materials can completely cut off completely with extraneous electrolyte, together When material surface can form more stable SEI film, be circulated throughout to be obviously improved the electrode obtained material in battery charging and discharging Coulombic efficiency and capacity stability in journey.

In conclusion doping type multi-layer core-shell silicon based composite material constructed in the present invention is negative as lithium ion battery There are the electrochemical properties such as capacity height, good rate capability, coulombic efficiency height, good cycle, expansion rate be low when pole uses.Using The lithium ion battery of doping type multi-layer core-shell silicon based composite material preparation have volume energy density height, good rate capability, Good cycling stability, the low characteristic of expansion.The doping type multi-layer core-shell silicon based composite material preparation repeatability is high and is suitable for Large-scale industrial production, and the water system cathode homogenate process system that industry generallys use can be directly applied to, it can be real Realize the scale application containing silicium cathode in field of lithium ion battery.

Detailed description of the invention

Fig. 1 is the structural schematic diagram of doping type multi-layer core-shell silicon based composite material of the invention.

Fig. 2 is the cycle performance figure of the full battery containing silicium cathode prepared by embodiment 1.

Specific embodiment

The present invention is further explained in the light of specific embodiments.

A kind of doping type multi-layer core-shell silicon based composite material provided by the invention, includes the silicon oxide compound of element doping Particle is as kernel, and the MULTILAYER COMPOSITE film layer that inner core particles surface closely coats is as shell.As shown in Figure 1, kernel 1 is element The silicon oxide particles of doping, wherein color gradually becomes shallower as from outside to inside indicates that the doped chemical content including lithium gradually drops It is low and without sharp interface.Simple substance nano silicon particles 2 have been uniformly distributed in the body phase of inner core particles, and in the meeting of inner core particles surface Since the doping insertion of elemental lithium forms one layer of fine and close lithium silicate compound 3.Carbon film layer 4 and doped metallic elements 5 and Doping type carbon film layer 6 is successively coated on the outer layer of inner core particles.

Embodiment 1

The silicon oxide compound particle (silicone atom ratio is 1:1) that 1000g median particle diameter is 6 μm is weighed to be placed in CVD furnace, and 900 DEG C are warming up under argon atmosphere protection with the rate of 20 DEG C/min.It is 300ccm's by gas velocity after being warming up to 900 DEG C Ammonia is passed through 60min into furnace, for carrying out N doping to silicon oxide compound particle.Then, continue 900 DEG C under argon atmosphere The acetylene gas that gas velocity is 300ccm is passed through 30min into furnace after holding 30min.Then, continue 900 DEG C of guarantors under argon atmosphere Be down to room temperature after holding 60min, obtain carbon-coated nitrogen doped silicon oxygen compound particle, in above-mentioned whole process argon gas with The gas velocity of 500ccm is passed through in CVD furnace.Resulting carbon coating nitrogen doped silicon oxygen compound particle is crossed into 500 mesh screens, then with It is molten that ANN aluminium nitrate nonahydrate and polyvinylpyrrolidone with the mass ratio of 5:1:0.1 are dispersed in the mixing of 2000ml second alcohol and water In agent, wherein ethyl alcohol and water volume ratio are 9:1.Finely dispersed suspension is stirred under 50 DEG C of constant temperature with mechanical agitator to It is dry, it then continues in tube furnace after being warming up to 800 DEG C under an argon atmosphere with the rate of 10 DEG C/min and is kept for 3 hours, realize aluminium Element is mixed with.Then, 500 mesh screens are crossed after cooled to room temperature in case subsequent operation.By previous step resulting materials It is stirred under 60 DEG C of constant temperature after mixing with 50% poly- acetimide solution and deionized water with the mass ratio of 50:1:100 It is extremely dry.It then continues in tube furnace after being warming up to 800 DEG C under an argon atmosphere with the rate of 5 DEG C/min and is kept for 2 hours, realized poly- The carbonization of acetimide clad and the doping in situ of nitrogen.After tube furnace is cooled to room temperature, takes out material and cross 500 mesh Sieve is in case subsequent operation.

Cross 600 meshes after lithium hydride coarse powder being crushed using planetary ball mill in drying room of the humidity lower than 20% Net obtains lithium hydride fine powder.Previous step resulting materials and lithium hydride powder are uniform in VC mixing machine with the mass ratio of 15:1 It is transferred in tube furnace after mixing 20min, then rises to 800 DEG C under an argon atmosphere with the heating rate of 10 DEG C/min and keeps 2 Hour.Material is taken out after natural cooling and crosses 500 mesh screens, obtains final product.Gained doping type multi-layer core-shell silicon substrate is compound Contain element silicon about 55wt% in material, oxygen element about 35wt%, elemental lithium about 5wt%, carbon about 3%, aluminium element is about 1wt%, nitrogen about 1wt%；It is uniform inside gained doping type multi-layer core-shell silicon based composite material by X-ray diffraction analysis The silicon nanocrystal particle size of dispersion is about 8nm.

By above-mentioned doping type multi-layer core-shell silicon based composite material and natural graphite, thickener and binder according to 10:87: The mass ratio of 1.5:1.5 is homogenized under the conditions of water system and is coated on copper foil, is then dried, is rolled, and is obtained siliceous negative Pole pole piece.

Half-cell assessment: above-mentioned siliceous cathode pole piece and diaphragm, lithium piece, stainless steel gasket are successively stacked and 200 μ are added dropwise CR2016 type half-cell is made in sealing after L electrolyte.Using Wuhan Lan electricity electronics limited liability company CT2001A type test equipment Test half-cell capacity and discharging efficiency.The de- lithium specific capacity reversible for the first time for measuring the half-cell containing silicium cathode is 461mAh/g, First charge-discharge efficiency (de- lithium stopping potential 0.8V) 91.8%.

Full battery assessment: above-mentioned siliceous cathode pole piece passes through cutting, vacuum bakeout, together with the positive plate of pairing and diaphragm After being wound and putting into plastic-aluminum shell of corresponding size, a certain amount of electrolyte and deairing and sealing are injected, one is obtained after chemical conversion The siliceous negative electrode lithium ion full battery of a about 3.2Ah.It should with the cell tester test of new Weir Electronics Co., Ltd., Shenzhen Capacity, average voltage of the full battery at 0.2C and 1C, and the charge and discharge cycles 500 times capacity that obtain are kept under 0.7C multiplying power Rate data.Thus obtaining full battery in the volume energy density of 0.2C and 1C is respectively 764Wh/L and 739Wh/L, 500 charge and discharges Capacity retention ratio after electricity circulation is 86.4%.Fig. 2 is the cycle performance figure of the full battery containing silicium cathode prepared by embodiment 1.

Unless otherwise instructed, subsequent embodiment, which is all made of, is made half-cell for gained negative electrode tab with 1 same procedure of embodiment And full battery, and test in identical equipment the specific capacity and efficiency for charge-discharge of the half-cell and full battery.

Embodiment 2

Compared to embodiment 1, embodiment 2 is adopted when carrying out element doping to silicon oxide compound particle using high temperature CVD method Ammonia is replaced with phosphine gas, remaining Parameter Conditions in entire CVD treatment process are same as Example 1, and are reacting After obtained carbon-coated phosphorous doped silicon oxygen compound particle.By 1000g carbon coating phosphorous doped silicon oxygen compound particle with ANN aluminium nitrate nonahydrate, sucrose and polyvinylpyrrolidone are dispersed in the mass ratio of 10:2:1:0.1 by high-speed stirred Spray drying treatment is then carried out in 4000ml deionized water.150 DEG C of inlet air temperature, 105 DEG C of outlet temperature, rotary-atomizing spray head Revolving speed 350Hz, charging rate 100g/min.Will spray drying products therefrom be transferred to van-type furnace, and under high pure nitrogen atmosphere with The rate of 10 DEG C/min is warming up to 800 DEG C, is then kept for 4 hours at 800 DEG C.During this high-temperature process, while realizing aluminium member The doping of element and char sucrose film forming cladding are on the surface of the material.Resulting materials are crossed 500 mesh screens in case of after by after treatment Continuous operation.Then, by mode same as Example 1, nitrogen is coated again in the way of the cladding carbonization of poly- acetimide and is mixed Miscellaneous carbon film layer simultaneously crosses 500 mesh screens in case subsequent operation.

Previous step resulting materials and lithium hydride fine powder are existed with the mass ratio of 15:1 in drying room of the humidity lower than 20% It is transferred in tube furnace after uniformly mixing 20min in VC mixing machine, then under an argon atmosphere with the heating rate liter of 10 DEG C/min To 800 DEG C and kept for 2 hours.Material is taken out after natural cooling and crosses 500 mesh screens, obtains final product.Gained doping type is more Contain element silicon about 54wt% in layer nucleocapsid silicon based composite material, oxygen element about 35wt%, elemental lithium about 6wt%, carbon is about 2.5%, aluminium element about 1wt%, nitrogen about 1wt%, P elements about 0.5wt%.Pass through X-ray diffraction analysis, gained doping Evenly dispersed silicon nanocrystal particle size is about 9.2nm inside type multi-layer core-shell silicon based composite material.

Use technique same as Example 1 be made measure the de- lithium specific capacity reversible for the first time of the half-cell containing silicium cathode for 463mAh/g, first charge-discharge efficiency 91.6%.It is respectively 767Wh/L that full battery, which is measured, in the volume energy density of 0.2C and 1C And 743Wh/L, the capacity retention ratio after 500 charge and discharge cycles are 85.9%.

Embodiment 3

Weigh the silicon oxide compound particle (silicone atom ratio is 1:1) and 200g ammonium hypophosphite that 1000g median particle diameter is 6 μm It is uniformly mixed in drying room of the humidity lower than 20%.The zirconium pearl of diameter 0.8mm is used to protect in the ball mill in gained mixture It is transferred in tube furnace after being carried out ball milling 2 hours under shield property atmosphere, is then warming up under argon atmosphere with the rate of 10 DEG C/min 4 hours subsequent cooled to room temperatures are kept after 900 DEG C, obtain the silicon oxide compound particle of P elements doping.By gained particle Pitch-coating is uniformly mixed and realized in hot type VC mixing machine with asphalt with the mass ratio of 10:1, then high-purity 900 DEG C are warming up to the rate of 10 DEG C/min in the batch-type furnace of nitrogen atmosphere and is kept for 2 hours, and subsequent cooled to room temperature is simultaneously 500 mesh screens are crossed, carbon-coated phosphorous doped silicon oxygen compound particle is obtained.Then, it by mode same as Example 2, utilizes Spray drying and high-temperature process carry out aluminium element doping.Then resulting materials and ammonium persulfate are passed through with the mass ratio of 30:1 Mechanical stirring is scattered in the dilute hydrochloric acid of 0.1mol/L and persistently stirs 30min under ice bath system, then in whipping process The aniline monomer solution that quality is twice of ammonium persulfate is added dropwise in above-mentioned mixed system, is then continued under condition of ice bath Stirring 8 hours.After reaction, vacuum after products therefrom deionized water and ethyl alcohol alternate repetition filtering and washing to neutrality is dried It is dry.Products therefrom will be filtered to be warming up to 850 DEG C in the batch-type furnace of high pure nitrogen atmosphere with the rate of 5 DEG C/min and keep 3 small When, subsequent cooled to room temperature simultaneously crosses 500 mesh screens in case subsequent operation.

Then, same as Example 1 to the technique of material obtained in the previous step progress elemental lithium doping.Final gained doping Contain element silicon about 54wt%, oxygen element about 34wt%, elemental lithium about 6wt%, carbon member in type multi-layer core-shell silicon based composite material Element about 3%, aluminium element about 1wt%, nitrogen about 1wt%, P elements about 0.5wt%；By X-ray diffraction analysis, gained is mixed Evenly dispersed silicon nanocrystal particle size is about 9.8nm inside miscellaneous type multi-layer core-shell silicon based composite material.Using with 1 phase of embodiment It is 459mAh/g, first charge-discharge efficiency that same technique, which is made and measures the de- lithium specific capacity reversible for the first time of the half-cell containing silicium cathode, 91.7%.It is respectively 762Wh/L and 738Wh/L that full battery, which is measured, in the volume energy density of 0.2C and 1C, and 500 charge and discharge follow Capacity retention ratio after ring is 85.7%.

Embodiment 4

Carbon-coated nitrogen doped silicon oxidation is prepared using technique identical with CVD doping method in embodiment 1 first Polymer beads.Gained particle is crossed after 500 mesh screens with copper acetate dihydrate, sucrose and polyvinylpyrrolidone with 10:2: The mass ratio of 1:0.1 carries out spray drying treatment after being dispersed in 4000ml deionized water by high-speed stirred.Air inlet 150 DEG C of temperature, 105 DEG C of outlet temperature, rotary-atomizing rotating speed of shower nozzle 350Hz, charging rate 100g/min.It will spray drying gained Product is warming up to 800 DEG C under high pure nitrogen atmosphere with the rate of 10 DEG C/min, is then kept for 4 hours at 800 DEG C.In this high temperature During processing, while the doping for realizing copper and char sucrose film forming cladding are on the surface of the material.Resulting materials are crossed into 500 mesh Sieve, and cladding is uniformly mixed with asphalt with the mass ratio of 10:1 by hot type VC mixing machine.Then, in argon atmospher Be warming up to 900 DEG C in the tube furnace enclosed with the rate of 10 DEG C/min, and after being kept for 1 hour into tube furnace with the gas of 100ccm Speed is passed through ammonia 30min for doping of the nitrogen on carbon coating layer simultaneously, then again 900 DEG C continue after being kept for 1 hour from It is so cooled to room temperature, crosses 500 mesh screens in case subsequent operation.

Compared to embodiment 1, the present embodiment is mixed in lithium technique subsequent, in addition to by the mass ratio of material and lithium hydride fine powder Example is changed to except 12:1 by 15:1, remaining parameter is identical.Contain silicon in final gained doping type multi-layer core-shell silicon based composite material Element about 53wt%, oxygen element about 33wt%, elemental lithium about 8wt%, carbon about 3%, copper about 0.5wt%, nitrogen About 2wt%；By X-ray diffraction analysis, evenly dispersed silicon nanometer inside gained doping type multi-layer core-shell silicon based composite material Crystallite dimension is about 8.8nm.It is made using technique same as Example 1 and measures the reversible for the first time de- of the half-cell containing silicium cathode Lithium specific capacity is 466mAh/g, first charge-discharge efficiency 92.3%.Full battery is measured in the volume energy density point of 0.2C and 1C Not Wei 768Wh/L and 744Wh/L, the capacity retention ratio after 500 charge and discharge cycles is 86.2%.

Embodiment 5

Weigh silicon oxide compound particle (silicone atom ratio is 1:1) and the ammonium dihydrogen phosphate that 1000g median particle diameter is 6 μm with The mass ratio of 10:3 is dispersed in 3000ml deionized water by mechanical stirring, then carries out spray drying treatment.Into 150 DEG C of air temperature, 105 DEG C of outlet temperature, rotary-atomizing rotating speed of shower nozzle 350Hz, charging rate 100g/min.Institute will be spray-dried It obtains product and is warming up to 950 DEG C under high pure nitrogen atmosphere with the rate of 10 DEG C/min, then kept for 3 hours at 950 DEG C.It is high herein It during temperature processing, while realizing the disproportionation of Si oxide and the doping of P elements, obtains the silicon oxide compound particle of phosphorus doping. Gained phosphorous doped silicon oxide particle is uniformly mixed in hot type VC mixing machine with asphalt with the mass ratio of 10:1 And realize the cladding of pitch, 900 DEG C then, which are warming up to, with the rate of 10 DEG C/min in the batch-type furnace of high pure nitrogen atmosphere keeps 2 Hour, subsequent cooled to room temperature simultaneously crosses 500 mesh screens, obtains carbon-coated phosphorous doped silicon oxygen compound particle.By gained Carbon coating nitrogen doped silicon oxygen compound particle cross 500 mesh screens, then with copper acetate dihydrate and polyvinylpyrrolidone with The mass ratio of 5:1:0.1 is dispersed in 2000ml ethyl alcohol and water mixed solvent, and wherein ethyl alcohol and water volume ratio are 9:1. Finely dispersed suspension mechanical agitator is stirred to doing under 50 DEG C of constant temperature, is then continued in tube furnace in argon atmosphere Under be warming up to 800 DEG C with the rate of 10 DEG C/min after kept for 3 hours, realize being mixed with for copper.Then, it naturally cools to 500 mesh screens are crossed after room temperature in case subsequent operation.The doping type carbon film layer then carried out coats and mixes lithium technique and embodiment 4 In it is identical.Contain element silicon about 54wt%, oxygen element about 33wt% in final gained doping type multi-layer core-shell silicon based composite material, Elemental lithium about 8wt%, carbon about 3%, copper about 0.5wt%, nitrogen about 1wt%, P elements about 0.5wt%；Pass through X X ray diffraction analysis x, the evenly dispersed silicon nanocrystal particle size in gained doping type multi-layer core-shell silicon based composite material inside are about 9.1nm.Use technique same as Example 1 be made measure the de- lithium specific capacity reversible for the first time of the half-cell containing silicium cathode for 460mAh/g, first charge-discharge efficiency 91.7%.It is respectively 763Wh/L that full battery, which is measured, in the volume energy density of 0.2C and 1C And 739Wh/L, the capacity retention ratio after 500 charge and discharge cycles are 85.1%.

Embodiment 6

Carbon-coated phosphorous doped silicon oxidation is prepared using technique identical with CVD doping method in embodiment 2 first Polymer beads.Gained particle is crossed after 500 mesh screens with four acetate hydrate manganese and polyvinylpyrrolidone with the matter of 10:1:0.1 Amount ratio uniform is scattered in 2000ml ethyl alcohol and water mixed solvent, and wherein ethyl alcohol and water volume ratio are 9:1.It will be finely dispersed Suspension mechanical agitator is stirred under 50 DEG C of constant temperature to doing, and is then continued in tube furnace under an argon atmosphere with 10 DEG C/min Rate be warming up to 800 DEG C after kept for 3 hours, realize being mixed with for manganese element.Then, 500 are crossed after cooled to room temperature Mesh screen is in case subsequent operation.

Resulting materials are uniformly mixed into cladding with asphalt by hot type VC mixing machine with the mass ratio of 10:1.With Afterwards, 900 DEG C are warming up to the rate of 10 DEG C/min in the tube furnace of argon atmosphere, and after being kept for 1 hour into tube furnace Phosphine gas 30min is passed through simultaneously with the gas velocity of 100ccm for doping of the P elements on carbon coating layer, then again 900 DEG C Continue cooled to room temperature after being kept for 1 hour, crosses 500 mesh screens in case subsequent operation.

The doping type carbon film layer cladding that then carries out and to mix lithium technique in the same manner as in Example 4.Final gained doping type Contain element silicon about 54wt%, oxygen element about 33wt%, elemental lithium about 8wt%, carbon in multi-layer core-shell silicon based composite material About 3%, manganese element about 1wt%, P elements about 1wt%；By X-ray diffraction analysis, gained doping type multi-layer core-shell silicon substrate is multiple Evenly dispersed silicon nanocrystal particle size is about 8.6nm inside condensation material.It is made to measure using technique same as Example 1 and contain The de- lithium specific capacity reversible for the first time of the half-cell of silicium cathode is 457mAh/g, first charge-discharge efficiency 91.9%.Measure full electricity Pond is respectively 760Wh/L and 737Wh/L in the volume energy density of 0.2C and 1C, and the capacity after 500 charge and discharge cycles is kept Rate is 84.2%.

Embodiment 7

Carbon-coated nitrogen doped silicon oxidation is prepared using technique identical with CVD doping method in embodiment 1 first Polymer beads, and it is spare to cross 500 mesh screens.It is using planetary ball mill that magnesium hydride is thick in drying room of the humidity lower than 20% 600 mesh screens are crossed after powder is broken, obtain hydrogenation magnesium powder.By previous step resulting materials and hydrogenation magnesium powder with the mass ratio of 70:1 It is transferred in tube furnace after uniformly mixing 20min in VC mixing machine, then under an argon atmosphere with the heating rate of 10 DEG C/min It rises to 850 DEG C and keeps progress magnesium elements doping in 2 hours, subsequent cooled to room temperature simultaneously crosses 500 mesh screens in case subsequent behaviour Make.The doping type carbon film layer cladding that then carries out and to mix lithium technique in the same manner as in Example 1.Final gained doping type multilayer core In shell silicon based composite material contain element silicon about 55wt%, oxygen element about 33wt%, elemental lithium about 7wt%, carbon about 3%, Magnesium elements about 1wt%, nitrogen about 1wt%；Pass through X-ray diffraction analysis, gained doping type multi-layer core-shell silicon based composite material Internal evenly dispersed silicon nanocrystal particle size is about 8.6nm.It is made and is measured containing silicium cathode using technique same as Example 1 Half-cell de- lithium specific capacity reversible for the first time be 453mAh/g, first charge-discharge efficiency 91.6%.Full battery is measured in 0.2C Volume energy density with 1C is respectively 756Wh/L and 733Wh/L, and the capacity retention ratio after 500 charge and discharge cycles is 83.9%.

Embodiment 8

Phosphorous doped silicon oxygen compound particle is prepared using technique in the same manner as in Example 3 first, then by gained Product is transferred in CVD furnace, and carries out carbon coating using technique similar to Example 1, obtains carbon-coated phosphorous doped silicon oxidation Polymer beads.Then, by resulting materials and copper acetate dihydrate, sucrose, 50% poly- acetimide solution and polyvinyl pyrrole Alkanone is dispersed in 4000ml deionized water with the mass ratio of 100:2:1:2:0.1, then by same as Example 2 Technique carries out spray drying and subsequent heat treatment.Realize the doping and nitrogen-doped carbon film layer of copper simultaneously during heating treatment Cladding.Then, resulting materials are crossed into 500 mesh screens and is doped by lithium technique of mixing same as Example 4.Final gained Element silicon about 54wt% in doping type multi-layer core-shell silicon based composite material, oxygen element about 34wt%, elemental lithium about 7wt%, carbon member Element about 3%, copper about 1wt%, nitrogen about 1wt%, P elements about 0.5wt%.By X-ray diffraction analysis, gained is mixed Evenly dispersed silicon nanocrystal particle size is about 8.2nm inside miscellaneous type multi-layer core-shell silicon based composite material.Using with 1 phase of embodiment It is 456mAh/g, first charge-discharge efficiency that same technique, which is made and measures the de- lithium specific capacity reversible for the first time of the half-cell containing silicium cathode, 91.5%.It is respectively 760Wh/L and 738Wh/L that full battery, which is measured, in the volume energy density of 0.2C and 1C, and 500 charge and discharge follow Capacity retention ratio after ring is 84.5%.

Embodiment 9

Weigh the silicon oxide compound particle (silicone atom ratio is 1:1) and the oxidation of 200g tri- two that 1000g median particle diameter is 6 μm Boron is uniformly mixed in drying room of the humidity lower than 20%, then in the ball mill with the zirconium pearl of diameter 0.8mm in protectiveness gas It is carried out ball milling 3 hours under atmosphere.Products therefrom is transferred in tube furnace and is warming up to the rate of 3 DEG C/min under argon atmosphere 950 DEG C of holdings, 4 hours subsequent cooled to room temperatures obtain the silicon oxide compound particle of boron element doping.Then, by with reality Apply the identical technique of example 3, carry out carbon film layer cladding using hot type VC mixing machine and subsequent heat treatment, by with 1 phase of embodiment Same technique utilizes spray drying and high-temperature process to carry out aluminium element doping.

The doping type carbon film layer cladding that then carries out and to mix lithium technique in the same manner as in Example 4.Final gained doping type Contain element silicon about 55wt%, oxygen element about 33wt%, elemental lithium about 8wt%, carbon in multi-layer core-shell silicon based composite material About 3%, aluminium element about 1wt%, boron element about 0.5wt%；Pass through X-ray diffraction analysis, gained doping type multi-layer core-shell silicon substrate The evenly dispersed silicon nanocrystal particle size of composite inner is about 8.8nm.It is made and is measured using technique same as Example 1 The de- lithium specific capacity reversible for the first time of half-cell containing silicium cathode is 453mAh/g, first charge-discharge efficiency 92.1%.Measure full electricity Pond is respectively 759Wh/L and 735Wh/L in the volume energy density of 0.2C and 1C, and the capacity after 500 charge and discharge cycles is kept Rate is 84.4%.

Embodiment 10

Compared to embodiment before, embodiment 10 adjusts the sequence being mixed with.It uses and implementation first Carbon-coated nitrogen doped silicon oxygen compound particle is prepared in the identical technique of CVD doping method in example 1.Then, using with reality Identical technique in example 4 is applied, nitrogen is carried out to previous step resulting materials in such a way that hot type VC is mixed and combined heat treatment doping The cladding of doped carbon film layer, to obtain the core-shell structure of double-layer carbon film layer cladding.

Then, by resulting materials in drying room of the humidity lower than 20% with lithium aluminium hydride reduction fine powder and lithium hydride fine powder with The mass ratio of 100:3:8 is transferred in tube furnace after uniformly mixing 20min in VC mixing machine, then under an argon atmosphere with 10 DEG C/heating rate of min rises to 800 DEG C and kept for 2 hours, the doping infiltration of aluminium element and elemental lithium is during which realized simultaneously.From Material is so taken out after cooling and crosses 500 mesh screens, obtains final product.Contain in gained doping type multi-layer core-shell silicon based composite material There are element silicon about 54wt%, oxygen element about 33wt%, elemental lithium about 7wt%, carbon about 3%, aluminium element about 1.5wt%, nitrogen Element about 1.5wt%.It is evenly dispersed inside gained doping type multi-layer core-shell silicon based composite material by X-ray diffraction analysis Silicon nanocrystal particle size is about 9.6nm.It is made using technique same as Example 1 and measures the half-cell containing silicium cathode for the first time Reversible de- lithium specific capacity is 449mAh/g, first charge-discharge efficiency 91.8%.Full battery is measured in the volume energy of 0.2C and 1C Density is respectively 753Wh/L and 731Wh/L, and the capacity retention ratio after 500 charge and discharge cycles is 83.7%.

Comparative example 1

Technical process similar embodiment 4, difference are in CVD treatment process not carry out nitrogen to silicon oxide compound particle Element doping.Evenly dispersed silicon nanocrystal particle size is about 8.5nm inside gained silicon based composite material particle.Half-cell and complete Cell Evaluation method is with embodiment 4, and the de- lithium specific capacity reversible for the first time for measuring the half-cell containing silicium cathode is 461mAh/g, for the first time Efficiency for charge-discharge 91.9%.Measuring volume energy density of the full battery at 0.2C and 1C is respectively 763Wh/L and 721Wh/L, Capacity retention ratio after 500 charge and discharge cycles is 84.7%.As can be seen that whether Si oxide inner core particles carry out N doping Capacity of the resulting materials under the small multiplying power of 0.2C and energy density influence are not obvious, but the two energy under the big multiplying power of 1C The gap of metric density is obvious.It can be in silicon oxygen this is because carrying out N doping for kernel silicon oxide compound particle in embodiment 4 Lone pair electrons are provided in chemical combination objects system, so as to promote electronics quickly to transmit in system, promote silicon oxide compound particle Conductivity so that the high rate performance of resulting materials is significantly improved.

Comparative example 2

Technical process similar embodiment 4 is distinguished in the carbonisation after being later period VC cladding pitch not to carbon packet Coating carries out N doping.Evenly dispersed silicon nanocrystal particle size is about 8.6nm inside gained silicon based composite material particle.Half electricity With embodiment 4, the de- lithium specific capacity reversible for the first time for measuring the half-cell containing silicium cathode is 458mAh/ for pond and full battery appraisal procedure G, first charge-discharge efficiency 91.7%.Measure volume energy density of the full battery at 0.2C and 1C be respectively 760Wh/L and 732Wh/L, the capacity retention ratio after 500 charge and discharge cycles are 84.5%.Again it can be seen that resulting materials are at small times of 0.2C The gap of capacity and energy density and embodiment 4 under rate is not obvious.But with Si oxide inner core particles in comparative example 1 The difference for carrying out N doping is compared, and whether the nitrogen of secondary cladding carbon film layer is doped to resulting materials at big times of 1C The lag effects of energy density are relatively small under rate.It is because while that N doping can provide lone pair electrons for mentioning twice Rise system conductivity and high rate performance, but the electric conductivity of kernel silicon oxide compound particle is obviously more compared to outer layer carbon film layer It is weak, for conductivity promoted respective degrees also become apparent, therefore the Heteroatom doping of kernel silicon oxide compound particle for The promotion of material high rate performance becomes apparent.

Comparative example 3

Technical process similar embodiment 4, difference is directly to select when elements doped lithium to be handled without ball mill crushing and sieving Lithium hydride coarse powder, and only in mortar grind 20min after just mixed with previous step obtained material, be then heat-treated work Skill is same as Example 4.Evenly dispersed silicon nanocrystal particle size is about 5.8nm inside gained silicon based composite material.Half-cell With full battery appraisal procedure with embodiment 4, the de- lithium specific capacity reversible for the first time for measuring the half-cell containing silicium cathode is 438mAh/g, First charge-discharge efficiency 88.9%.Measure volume energy density of the full battery at 0.2C and 1C be respectively 722Wh/L and 677Wh/L, the capacity retention ratio after 500 charge and discharge cycles are 79.8%.Lithium hydride powder in comparative example 3 is without partial size Control, there are the lithium hydride particles that a large amount of partial sizes are far longer than silicon oxide compound particle.Lithium hydride grain diameter is excessive to be will lead to The lithium amount that the silicon oxide compound particle combined when its inside nuclear proliferation finally adulterates is excessively high, so that form positive lithium metasilicate even oxygen Change lithium.Therefore, compared to embodiment 4, slurry alkalinity of the resulting materials in water system homogenization process is higher in comparative example 3, causes Its slurry form is slightly unstable, to cause the loss of active silicon materials and the deterioration of coating quality, and has eventually led to full electricity Comprehensive deterioration of the chemical property in pond.

Comparative example 4

Technical process similar embodiment 2, difference are to carry out metal member not over spray drying and subsequent heat treatment Element doping.Evenly dispersed silicon nanocrystal particle size is about 7.3nm inside gained silicon based composite material.Half-cell and full battery are commented Method is estimated with embodiment 2, and the de- lithium specific capacity reversible for the first time for measuring the half-cell containing silicium cathode is 454mAh/g, first charge-discharge Efficiency 91.1%.It is respectively 759Wh/L and 733Wh/L, 500 charge and discharges that full battery, which is measured, in the volume energy density of 0.2C and 1C Capacity retention ratio after electricity circulation is 81.7%.As can be seen that compared to embodiment 2, the small multiplying power of products therefrom in comparative example 4 Capacity and first charge-discharge efficiency gap are not obvious, but it is declined slightly in terms of big rate capability and cyclical stability. This is because the metallic element of doping is usually with super in example 2 in resulting doping type multi-layer core-shell silicon based composite material The form stable of thin nano particle exists, this acts not only as anchor point and effectively inhibits to be led by the expansion of internal layer nano silicon particles The carbon film coated layer of cause ruptures, and is also used as Active Growth site to promote the firm packet of doping type carbon-coating in subsequent step It covers, and then improves the structural stability of resulting materials and its high-velocity electrons conduction energy when being applied to negative electrode of lithium ion battery Power, therefore make it have the high rate performance and cyclical stability being obviously improved.

Comparative example 5

Technical process similar embodiment 4, difference is not carry out carbon film layer cladding in CVD treatment process, and is spraying Carbon film layer cladding is not doped after the dry heat treatment of mist.Evenly dispersed silicon nanocrystal inside gained silicon based composite material Size is about 6.6nm.Half-cell and full battery appraisal procedure measure the reversible for the first time of the half-cell containing silicium cathode with embodiment 4 De- lithium specific capacity is 455mAh/g, first charge-discharge efficiency 91.4%.It is close to measure volume energy of the full battery at 0.2C and 1C Degree is respectively 761Wh/L and 705Wh/L, and the capacity retention ratio after 500 charge and discharge cycles is 72.7%.As can be seen that comparing In embodiment 4, capacity and energy density gap of 5 resulting materials of comparative example under small multiplying power are relatively small, but under big multiplying power Energy density gap and 500 cycle charge-discharges after capacity keep gap it is larger.This can be attributed primarily to no carbon and protects In the case where sheath, the electric conductivity of resulting materials is remarkably decreased, and keeps its high rate performance poor；Meanwhile in the guarantor of not carbon film layer Under shield, volume expansion of nano silicon particles during repeated charge in inner core particles cannot effectively be contained, and because This causes material dusting and cycle performance of battery obviously to weaken.

Embodiment electrochemical data summarizes:

The above is only presently preferred embodiments of the present invention, is not intended to limit the present invention in any form, any ripe Professional and technical personnel is known, without departing from the scope of the present invention, according to the technical essence of the invention, to the above reality Any simple modifications, equivalent substitutions and improvements etc. made by example are applied, it is fallen within the scope of protection of the technical scheme of the present invention It is interior.

Claims

1. a kind of doping type multi-layer core-shell silicon based composite material for lithium ion battery, it is characterised in that: the doping type is more In layer nucleocapsid silicon based composite material, other than it must adulterate Li element, at least also doped with a kind of nonmetalloid and one kind Metallic element；The doping type multi-layer core-shell silicon based composite material structure is to be with the silicon oxide compound particle with element doping Kernel, the multilayer complex films closely coated using inner core particles surface is shells；It include evenly dispersed list in the inner core particles Matter nano silicon particles, wherein the content of doped chemical gradually decreases from outside to inside and without sharp interface, while inner core particles surface Since the doping insertion of elemental lithium forms one layer of fine and close lithium silicate compound；The multilayer complex films be carbon film layer and by The doping type composite film of carbon film layer and the compound composition of other elements component；The doped chemical is selected from N, S, P, B, Mg, Al, One of Cu, Mn, Ca, Zn or a variety of, wherein metal-doped element is present in shell film layer.

2. the doping type multi-layer core-shell silicon based composite material according to claim 1 for lithium ion battery, feature exist In: the median particle diameter of the doping type multi-layer core-shell silicon based composite material between 0.3-30 μm, the wherein intermediate value of inner core particles Partial size is between 0.3-25 μm, and the median particle diameter for the simple substance nano silicon particles being distributed in kernel silicon oxide compound particle exists Between 0.1-50nm；Inner core particles outer cladding MULTILAYER COMPOSITE thicknesses of layers between 0.005-10 μm；

In the inner core particles, silicon content 49.9-79.9wt%, oxygen element content 20-50wt%, doped chemical contain Amount is 0.01-10%, and silicon, oxygen, doped chemical equal size summation are 100%；The multilayer complex films and silicon oxide compound kernel The weight ratio of particle is 0.01:100-25:100, in the doping type composite film, element doping amount 0.01-5% it Between.

3. the preparation method of the doping type multi-layer core-shell silicon based composite material described in claim 1 for lithium ion battery, It is characterized in that: the following steps are included:

(2) it is then carried out using doping type silicon oxide compound obtained in step (1) as kernel in its coated with carbon film layer Broken and sub-sieve；

(3) step (2) resulting materials are uniformly mixed with the precursor species containing doped metallic elements, then non-oxidizable Heat treatment doping is carried out in atmosphere, and carries out broken and sub-sieve；

(4) using step (3) resulting materials as kernel, one layer of element doping type carbon film is uniformly coated again on its surface, with laggard Row is crushed and sub-sieve；

(5) step (4) resulting materials are uniformly mixed with lithium-containing compound powder, and is carried out at heating in nonoxidizing atmosphere Reason, makes doped chemical in elemental lithium and body phase further diffuse into silicon oxide compound particle, then carries out at broken and sub-sieve Reason, finally obtains doping type multi-layer core-shell silicon based composite material；

4. the preparation side of the doping type multi-layer core-shell silicon based composite material according to claim 3 for lithium ion battery Method, it is characterised in that: in step (1):

Silicon and oxygen element stoichiometric ratio in the silicon oxide compound particle are 1:0.5-1:1.5, and median particle size range exists Between 0.1-20 μm；

The element doping that directly carries out to silicon oxide particles passes through high temperature vapor deposition, high temperature solid-phase sintering, spray drying Or one or more of the methods of ball milling doping combination is realized；

Instrument used by the doping method is in CVD furnace, tube furnace, atmosphere batch-type furnace, ball mill or spray dryer etc. One or more combination realize；

The doped chemical is N, P, B, one or more of elements such as S, F；

The dopant is the gas or solid below containing one or more of doped chemicals, as ammonia, hydrogen phosphide, red phosphorus, Ammonium hypophosphite, ammonium dihydrogen phosphate, diboron trioxide, boric acid, hydrogen sulfide, thiocarbamide, thioacetamide, ammonium fluoride；

5. the preparation side of the doping type multi-layer core-shell silicon based composite material according to claim 3 for lithium ion battery Method, it is characterised in that: in step (2):

The carbon film layer is directly obtained by way of chemical vapor deposition, or is existed again by carrying out carbon matrix precursor cladding in advance The mode that high-temperature heat treatment carbonization is carried out in non-oxidizing atmosphere obtains；

The method for coating of the carbon matrix precursor is solid phase method or liquid phase method, coats the instrument used as mechanical fusion machine, machinery Blender, VC mixing machine, cladding kettle, hydrothermal reaction kettle, spray drying, in sand mill or high speed disperser any one or it is several Kind of combination, the solvent that when cladding selects is water, methanol, ethyl alcohol, ethylene glycol, isopropanol, n-butanol, acetone, N- crassitude Ketone, espeleton, tetrahydrofuran, benzene,toluene,xylene, N,N-dimethylformamide, DMAC N,N' dimethyl acetamide, three chloromethanes The combination of one or more of alkane etc.；The additive selected when cladding is dilute hydrochloric acid, p-methyl benzenesulfonic acid, ammonium persulfate, peroxidating The combination of one or more of hydrogen, polyvinylpyrrolidone, lauryl sodium sulfate, neopelex etc.；

The carbon matrix precursor is asphalt, coal tar pitch, polyvinyl alcohol, epoxy resin, polyacrylonitrile, poly-methyl methacrylate One of ester, aniline, pyrroles, thiophene, glucose, sucrose, polyacrylic acid etc.；

The heat treatment carbonization device therefor is rotary furnace, roller kilns, Electric heat oven, pushed bat kiln, tube furnace or atmosphere batch-type furnace Any one in；

The temperature of the high-temperature heat treatment carbonization is 550-1100 DEG C, and heating rate is between 2-50 DEG C/min, soaking time It is 1-24 hours；

6. the preparation side of the doping type multi-layer core-shell silicon based composite material according to claim 3 for lithium ion battery Method, it is characterised in that: in step (3):

The doped metallic elements are Ca, Mg, Al, Zn, Cu, Mn, Zr, one or more of Fe combination, the presoma object Matter is metal salt, metal oxide, metal hydroxides or the metal hydride of doped metallic elements；

Mixed method includes solid phase mixing or liquid phase mixing, is mixed using mechanical stirring, sand mill, ball mill, spray drying, VC The combination of one or more of machine etc. is realized；

The solvent used in liquid phase mixed process includes water, methanol, ethyl alcohol, isopropanol, acetone, N-Methyl pyrrolidone, acetic acid The combination of one or more of ethyl ester etc.；

The additive of selection involved in mixed process includes sucrose, glucose, poly- acetimide, polyacrylonitrile, polyacrylic acid, gathers The combination of one or more of vinylpyrrolidone, lauryl sodium sulfate, neopelex etc.；

The heat treatment doping device therefor is any in roller kilns, rotary furnace, pushed bat kiln, atmosphere batch-type furnace or tube furnace etc. It is a kind of；

The heat treatment doping temperature is 700-1200 DEG C, and heating rate is between 2-50 DEG C/min, soaking time 0.5- 12 hours；

7. the preparation side of the doping type multi-layer core-shell silicon based composite material according to claim 3 for lithium ion battery Method, it is characterised in that: in step (4):

The element doping type carbon film obtains in the following manner: self-framework being selected to contain heteroatomic organic carbon matrix precursor It is coated, is then heat-treated in non-oxidizing atmosphere, presoma realizes heteroatomic doping in situ while carbonization； Or coat dopant together after mixing with carbon matrix precursor, heat treatment carbonization is then carried out in non-oxidizing atmosphere While realize to the element doping of carbon film layer；Or after the completion of carbon film layer presoma coats and carries out heat treated carbon again into Row element doping；

The carbon matrix precursor is asphalt, coal tar pitch, polyvinyl alcohol, epoxy resin, polyacrylonitrile, poly- acetimide, poly- first One of base methyl acrylate, aniline, pyrroles, thiophene, glucose, sucrose, polyacrylic acid etc.；

The dopant is urea, melamine, dicyanodiamine, red phosphorus, ammonium hypophosphite, boric acid, ammonia, hydrogen phosphide, vulcanization One of hydrogen etc.；

The temperature of the heat treatment carbonization is 600-1000 DEG C, and between 2-50 DEG C/min, soaking time is heating rate 0.5-12 hours；

8. the preparation side of the doping type multi-layer core-shell silicon based composite material according to claim 3 for lithium ion battery Method, it is characterised in that: in step (5):

The grinding mode of the lithium-containing compound powder is mortar grinder, in ball mill, turbine type crushing machine, airslide disintegrating mill Any one；

Mixed method is using high speed disperser, high-speed stirred mill, ball mill, cone-type mixer, mixing screw, stirring-type mixing Any one in machine or VC mixing machine；

The heat treatment device therefor is any one in rotary furnace, roller kilns, pushed bat kiln, tube furnace or atmosphere batch-type furnace etc. Kind；

The temperature of the heat treatment is 500-1000 DEG C, and heating rate is between 2-50 DEG C/min, soaking time 0.5- 15 hours；

9. a kind of negative electrode of lithium ion battery, it is characterised in that: the doping type multi-layer core-shell silicon substrate comprising claims 1 or 2 is compound Material.

10. a kind of lithium ion battery, it is characterised in that: prepared using negative electrode of lithium ion battery as claimed in claim 9.