CN117810380A - Negative electrode composite material and preparation method and application thereof - Google Patents
Negative electrode composite material and preparation method and application thereof Download PDFInfo
- Publication number
- CN117810380A CN117810380A CN202211230393.6A CN202211230393A CN117810380A CN 117810380 A CN117810380 A CN 117810380A CN 202211230393 A CN202211230393 A CN 202211230393A CN 117810380 A CN117810380 A CN 117810380A
- Authority
- CN
- China
- Prior art keywords
- negative electrode
- type silicon
- silicon crystal
- crystal material
- source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000002131 composite material Substances 0.000 title claims abstract description 135
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 159
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 157
- 239000010703 silicon Substances 0.000 claims abstract description 157
- 239000000463 material Substances 0.000 claims abstract description 120
- 239000013078 crystal Substances 0.000 claims abstract description 100
- 239000002245 particle Substances 0.000 claims abstract description 62
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 42
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 50
- 238000010438 heat treatment Methods 0.000 claims description 42
- 229910052799 carbon Inorganic materials 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 13
- 239000000843 powder Substances 0.000 claims description 8
- 230000007423 decrease Effects 0.000 claims description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 239000011574 phosphorus Substances 0.000 claims description 4
- 239000000470 constituent Substances 0.000 claims description 3
- 230000003247 decreasing effect Effects 0.000 claims description 3
- 238000011065 in-situ storage Methods 0.000 claims description 3
- 229910052785 arsenic Inorganic materials 0.000 claims description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims description 2
- 230000000052 comparative effect Effects 0.000 description 20
- 238000012360 testing method Methods 0.000 description 16
- 239000002178 crystalline material Substances 0.000 description 12
- 239000007784 solid electrolyte Substances 0.000 description 11
- -1 nickel cobalt aluminum Chemical compound 0.000 description 8
- 239000007787 solid Substances 0.000 description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 7
- 239000010410 layer Substances 0.000 description 7
- 229910052744 lithium Inorganic materials 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- 239000011267 electrode slurry Substances 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000002210 silicon-based material Substances 0.000 description 5
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 4
- 239000004698 Polyethylene Substances 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000006183 anode active material Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000006258 conductive agent Substances 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 238000009616 inductively coupled plasma Methods 0.000 description 3
- 229910003002 lithium salt Inorganic materials 0.000 description 3
- 159000000002 lithium salts Chemical class 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000005543 nano-size silicon particle Substances 0.000 description 3
- 239000007773 negative electrode material Substances 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 2
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000005169 Debye-Scherrer Methods 0.000 description 2
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000002041 carbon nanotube Substances 0.000 description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 description 2
- 230000010261 cell growth Effects 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 229910021419 crystalline silicon Inorganic materials 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 239000003574 free electron Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 229910000073 phosphorus hydride Inorganic materials 0.000 description 2
- 239000002985 plastic film Substances 0.000 description 2
- 229920006255 plastic film Polymers 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 description 1
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 description 1
- 229910013716 LiNi Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000002296 dynamic light scattering Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 238000010574 gas phase reaction Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000012010 growth Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 239000011244 liquid electrolyte Substances 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 description 1
- 229910001486 lithium perchlorate Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- YQCIWBXEVYWRCW-UHFFFAOYSA-N methane;sulfane Chemical compound C.S YQCIWBXEVYWRCW-UHFFFAOYSA-N 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920006122 polyamide resin Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000012113 quantitative test Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- ZUHZGEOKBKGPSW-UHFFFAOYSA-N tetraglyme Chemical compound COCCOCCOCCOCCOC ZUHZGEOKBKGPSW-UHFFFAOYSA-N 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application provides a negative electrode composite material, and a preparation method and application thereof. The negative electrode composite material comprises an ultrafine N-type silicon crystal material and a conductive carbon material, wherein the ultrafine N-type silicon crystal material is dispersed in the conductive carbon material; the outer surface of the negative electrode composite material particles is not exposed by the ultra-micro N-type silicon crystal material, and the D50 particle size of the ultra-micro N-type silicon crystal material is less than or equal to 5nm. The cathode composite material has good structural stability, higher conductivity, better multiplying power performance, good expansion characteristic and cycle performance, and can be used for providing an electrochemical device with good multiplying power performance and cycle performance.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a negative electrode composite material and a preparation method and application thereof.
Background
Crystalline silicon materials are often used as negative active materials for batteries because of their high theoretical specific capacities. However, the short plates of crystalline silicon material have poor expansion resistance, the volume change of charge and discharge is extremely large, and cracks can be formed when the volume is increased and reduced each time, so that the normal performance of the battery is affected. And elemental silicon is a semiconductor material with poor electron conductivity, which also greatly limits its application as an electrode active material in batteries. At present, the anti-expansion performance of the silicon material is often improved by forming a coating layer on the surface of the silicon material particles, but the effect of relieving the expansion effect is limited, and the silicon material particles are still easy to crack and deteriorate the cycle performance of the battery.
Disclosure of Invention
In view of this, the present application provides a negative electrode composite material. The cathode composite material has good structural stability, higher conductivity, better multiplying power performance, good expansion characteristic and cycle performance, and can be used for providing an electrochemical device with good multiplying power performance and cycle performance.
The first aspect of the application provides a negative electrode composite material, which comprises an ultrafine N-type silicon crystal material and a conductive carbon material, wherein the ultrafine N-type silicon crystal material is dispersed in the conductive carbon material; the outer surface of the negative electrode composite material particles is not exposed by the ultra-micro N-type silicon crystal material, and the D50 particle size of the ultra-micro N-type silicon crystal material is less than or equal to 5nm.
The superfine N-type silicon crystal material has more free electrons and strong conductivity, and the superfine N-type silicon crystal material has extremely small size so as to realize dispersion in conductive carbon, so that the anode composite material has better uniformity and strong conductivity, and the whole anode composite material 100 has higher multiplying power. In addition, each superfine N-type silicon crystal material is wrapped by a compact conductive carbon material, the risk of cracking of the superfine N-type silicon crystal material is obviously reduced, and further the expansion characteristic and the long-cycle characteristic of the negative electrode composite material can be obviously improved, and the stability of the negative electrode composite material is improved.
Optionally, the conductive carbon material comprises amorphous carbon.
Optionally, the anode composite material is granular, and the mass content of the ultrafine N-type silicon crystal material in the anode composite material gradually decreases from the center of the anode composite material to the outer surface.
Optionally, in the single negative electrode composite material, in the region distributed with the ultrafine N-type silicon crystal material, the lowest mass concentration of silicon element is A, and the highest mass concentration is B, wherein A is more than or equal to 0.9B.
Optionally, the constituent elements of the ultramicro N-type silicon crystal material comprise Si element and doping element; the doping element includes, but is not limited to, a phosphorus element.
Optionally, the atomic volume concentration of the doping element in the ultra-micro N-type silicon crystal material is less than or equal to 5 multiplied by 10 21 atoms/cm 3 . Preferably, the atomic volume concentration of the doping element in the ultra-micro N-type silicon crystal material is less than or equal to 1 multiplied by 10 21 atoms/cm 3 . Further preferably, the atomic volume concentration of the doping element in the ultra-fine N-type silicon crystal material is less than or equal to 2×10 20 atoms/cm 3 . Still further preferably, the atomic volume concentration of the doping element in the ultra-fine N-type silicon crystal material is 1×10 or less 20 atoms/cm 3 。
Optionally, the mass percentage of silicon element in the negative electrode composite material is 25% -75%. Preferably, the mass percentage of silicon element in the anode composite material is 40% -70%.
Preferably, the D50 particle size of the ultra-micro N-type silicon crystal material is less than or equal to 0.5nm. Further preferably, the D50 particle size of the ultra-fine N-type silicon crystal material is less than or equal to 0.2nm.
Optionally, the grain size of the ultra-fine N-type silicon crystal material is less than or equal to 3nm. Preferably, the grain size of the ultra-micro N-type silicon crystal material is in the range of 0.1nm-1 nm.
Optionally, the D50 particle size of the negative electrode composite is less than or equal to 30 μm. Preferably, the D50 particle size of the negative electrode composite material is less than or equal to 15 μm. Further preferably, the D50 particle diameter of the negative electrode composite material is in the range of 3 μm to 15 μm.
Optionally, the negative electrode composite has a powder resistivity of less than or equal to 2.5mΩ·cm.
The second aspect of the application provides a preparation method of a negative electrode composite material, which comprises the following steps:
introducing a certain amount of silicon source, doping source and carbon source into a heating device for heating, wherein the carbon source forms conductive carbon material, and the conductive carbon material is dispersed with an ultra-micro N-type silicon crystal material formed by in-situ reaction of the silicon source and the doping source so as to obtain a negative electrode composite material;
the negative electrode composite material comprises an ultrafine N-type silicon crystal material and a conductive carbon material, wherein the ultrafine N-type silicon crystal material is dispersed in the conductive carbon material; the outer surface of the negative electrode composite material particles is not exposed by the ultra-micro N-type silicon crystal material, and the D50 particle size of the ultra-micro N-type silicon crystal material is less than or equal to 5nm.
The preparation method is simple to operate, high in process controllability and high in production efficiency, and is suitable for large-scale industrial preparation.
Optionally, the heating treatment is performed by introducing a certain amount of silicon source, doping source and carbon source into a heating device, and at least comprises the following steps:
(1) Preheating: introducing a carbon source into the heating device;
(2) And (3) heat treatment: replacing the carbon source with the silicon source and the doping source;
(3) Post-treatment: the silicon source is replaced with the carbon source.
Optionally, in the heat treatment, the amount of silicon source fed to the heating device is decreased.
Optionally, the silicon source includes, but is not limited to, siH 4 。
Optionally, the doping source includes, but is not limited to, a phosphine.
Alternatively, the carbon source includes, but is not limited to, acetylene.
Optionally, the conditions of the heating treatment are: treating at 400-2000 deg.c for 0.25-4 hr.
Optionally, the heating device further comprises a conductive carbon skeleton material preset in the heating device.
Optionally, the conductive carbon backbone material includes, but is not limited to, activated carbon.
A third aspect of the present application provides a negative electrode tab comprising the negative electrode composite material provided in the first aspect of the present application or prepared according to the improved preparation method of the second aspect of the present application.
The electrode plate has good multiplying power performance, cycle performance and safety performance.
A fourth aspect of the present application provides an electrochemical device comprising the negative electrode tab provided in the third aspect of the present application.
The electrochemical device comprises a secondary battery, and the secondary battery has high rate capability, good cycle performance and high safety.
Drawings
Fig. 1 is a schematic and schematic diagram of a negative electrode composite material according to an embodiment of the present application;
FIG. 2A is a schematic diagram of the distribution of the ultra-fine N-type silicon crystal material in the negative electrode composite material according to an embodiment of the present application;
fig. 2B is a correspondence between the mass concentration and the gray scale of the ultramicro N-type silicon crystal material.
Reference numerals illustrate: 100-negative electrode composite material; 10-ultra-micro N-type silicon crystal material; 20-conductive carbon material.
Detailed Description
In particular, see fig. 1. The embodiment of the application provides a negative electrode composite material 100, wherein the negative electrode composite material 100 comprises an ultrafine N-type silicon crystal material 10 and a conductive carbon material 20, and the ultrafine N-type silicon crystal material 10 is dispersed in the conductive carbon material 20; the outer surface of the particles of the negative electrode composite material 100 is not exposed with the ultra-micro N-type silicon crystal material 10, and the D50 particle size of the ultra-micro N-type silicon crystal material 10 is less than or equal to 5nm.
The ultramicro N-type silicon crystal material 10 has more free electrons and strong conductivity, and the D50 particle size of the ultramicro N-type silicon crystal material 10 is smaller than 5nm, the size is extremely small, and when the ultramicro N-type silicon crystal material is dispersed in a conductive carbon material, the particle feeling is extremely weak, and the ultramicro N-type silicon crystal material and the conductive carbon material can be mixed highly, so that the uniformity of the cathode composite material is better, the conductivity is strong, and the whole cathode composite material 100 has higher multiplying power performance. In addition, each ultra-fine N-type silicon crystalline material 10 is surrounded by a dense conductive carbon material 20, and the smaller the size of the silicon crystalline material, the larger the gibbs free energy of fracture increase (i.e., the larger the energy wall across which the particle fracture needs to be), and the smaller the size can effectively suppress the fracture and pulverization of the silicon crystalline material. On the other hand, the existence of the conductive carbon material 20 can also protect the silicon crystal material, and the problem of increased side reaction between the anode material and the electrolyte caused by overlarge specific surface area of the silicon crystal material can be effectively solved. In addition, the small-size silicon crystal material has small absolute thermal expansion volume and small impact force on the conductive carbon material 20 when the volume expansion occurs, and the silicon crystal material is difficult to break through the package of the conductive carbon material 20 to be exposed, so that the conductive carbon material 20 can permanently inhibit the expansion of the ultra-micro N-type silicon crystal material 10 in the charge-discharge cycle process, and further the expansion characteristic and the long cycle characteristic of the cathode composite material 100 can be remarkably improved.
In this application, illustratively, the D50 particle size of the ultra-fine N-type silicon crystalline material 10 may be 0.1nm, 0.15nm, 0.2nm, 0.25nm, 0.3nm, 0.35nm, 0.4nm, 0.45nm, 0.5nm, 0.55nm, 0.6nm, 0.65nm, 0.7nm, 0.75nm, 0.8nm, 0.85nm, 0.9nm, 0.95nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm, 4.5nm, 5nm, etc. The D50 particle size of the ultrafine N-type silicon crystal material 10 is too large, which may result in the enhancement of the particle feel of the negative electrode composite material, the deterioration of the dispersion effect of the ultrafine N-type silicon crystal material 10 in the conductive carbon material 20, and the decrease of gibbs free energy, which is required to increase the cracking thereof, which may impair the expansion characteristics and long cycle characteristics of the negative electrode composite material 100.
In some embodiments of the present application, the D50 particle size of the ultra-fine N-type silicon crystalline material 10 is less than or equal to 0.5nm. Further preferably, in some embodiments, the D50 particle size of the ultra-fine N-type silicon crystalline material 10 is less than or equal to 0.2nm. It can be understood that the ultra-micro N-type silicon crystal material in the anode composite material 100 provided in the embodiment of the present application is obtained by vapor phase growth, and the growth speed of the crystal is similar under the atmosphere condition, so that the dimensions of the ultra-micro N-type silicon crystal material in the same anode composite material 100 are also similar. In the present application, the D50 particle size of the ultrafine N-type silicon crystal particles defined in the present application can be considered by observing the sizes of a certain number of ultrafine N-type silicon crystal particles in a cross-sectional sample of the anode composite material 100 in different regions under a transmission electron microscope (Transmission Electron Microscope, TEM).
In some embodiments of the present application, the grain size of the ultra-fine N-type silicon crystalline material 10 (as calculated by the Debye-Scherrer equation after X-ray diffraction testing) is less than or equal to 3nm. Preferably, in some embodiments, the grain size of the ultra-fine N-type silicon crystalline material 10 is in the range of 0.1nm-1 nm. Illustratively, the grain size of the ultra-fine N-type silicon crystalline material 10 may be 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 1.5nm, 2nm, 2.5nm, 3nm, and the like.
In some embodiments of the present application, the D50 particle size (average particle size, as measured by dynamic light scattering) of the negative electrode composite material 100 is less than or equal to 30 μm. In some embodiments, the D50 particle size of the negative electrode composite material 100 is in the range of 3 μm to 15 μm. Illustratively, the D50 particle size of the negative electrode composite material 100 may be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc. Controlling the D50 particle size of the anode composite material 100 within the above range is not only beneficial to ensuring that the specific surface area of the anode composite material 100 is within a proper range, so as to ensure that electrolyte in a subsequent battery can better infiltrate the anode active material, but also can control the deintercalation path of active metal ions to be shorter, so that the electrochemical performance of the anode active material (i.e., the battery) can be fully exerted.
In some embodiments of the present application, the anode composite 100 is in the form of particles, please refer to fig. 2A-2B, and the mass content of the ultrafine N-type silicon crystal material 10 in the single anode composite 100 gradually decreases from the center of the anode composite 100 to the outer surface. As can be appreciated, the distribution of the ultrafine N-type silicon crystal material in the central portion of the anode composite material 100 is more, the higher the mass content of the conductive carbon material along the extending direction of the diameter thereof, the more compact the connection between the conductive carbons, so that the structure of the whole anode composite material is more stable. From the macroscopic point of view, the difficulty of struggling the outer layer material from the center of the sphere or the spheroid is relatively large, and the structural design is beneficial to further reducing the risks of cracking and pulverization of the cathode composite material caused by the volume expansion of the silicon crystal material. In addition, the conductivity and the ion conductivity of the conductive carbon material 20 are both stronger than those of the ultrafine N-type silicon crystal material 10 (equivalent to a semiconductor material), and the structural design is also beneficial to constructing an efficient conductive and ion conductive network in a single negative electrode composite material, so that the multiplying power performance of the negative electrode composite material is further improved.
In some embodiments of the present application, the mass percentage of silicon element in the negative electrode composite material 100 is 25% -75%. In some embodiments, the mass percentage of the silicon element in the negative electrode composite material is 40% -70%. Illustratively, the mass percent of elemental silicon in the negative electrode composite material 100 may be 25%, 30%, 35%, 40%, 42.5%, 45%, 47.5%, 50%, 52.5%, 55%, 60%, 62.5%, 65%, 67.5%, 70%, 75%, etc. The mass percentage of the silicon element is controlled within a certain range, so that the content of the anode active material is high, and the sufficient conductive carbon material 20 in the anode composite material can form a high-efficiency conductive and ion-conductive network and the structural stability of the anode composite material 100.
In some embodiments of the present application, in the single negative electrode composite material 100, in the region where the ultrafine N-type silicon crystal material 10 is distributed, the lowest mass concentration of silicon element is a, and the highest mass concentration is B, where a is greater than or equal to 0.9B. Illustratively, the value of a may be 0.9B, 0.91B, 0.92B, 0.93B, 0.94B, 0.95B, 0.96B, 0.97B, 0.98B, 0.99B, etc. The difference in mass concentration distribution of the silicon element represents the difference in mass concentration distribution of the ultrafine N-type silicon crystal material 10 in the negative electrode composite material 100, and the difference in concentration distribution of the silicon element is controlled within the above range, so that not only can an efficient conductive and ion-conducting network be formed in the negative electrode composite material 100, but also the concentration effect of expansion caused by excessive concentration of the ultrafine N-type silicon crystal material in the center of the negative electrode composite material 100 can be avoided, thereby further improving the structural stability of the negative electrode composite material 100.
In some embodiments of the present application, the constituent elements of the ultrafine N-type silicon crystal material 10 include Si element and doping element; the doping elements include, but are not limited to, phosphorus elements and/or arsenic elements. In some cases, the doping element may further include other pentavalent elements, and may be, for example, nitrogen element or the like.
In some embodiments of the present application, the doping element has an atomic volume concentration of less than or equal to 5×10 21 atoms/cm 3 . Preferably, in some embodiments, the atomic volume concentration of the doping element in the ultra-fine N-type silicon crystalline material 10 is less than or equal to 1 x 10 21 atoms/cm 3 . Further preferably, in some embodiments, the atomic volume concentration of the doping element in the ultra-fine N-type silicon crystalline material 10 is less than or equal to 2 x 10 20 atoms/cm 3 . Still further preferably, in some embodiments, the atomic volume concentration of the doping element in the ultra-fine N-type silicon crystalline material 10 is less than or equal to 1 x 10 20 atoms/cm 3 . The larger the atomic volume concentration of the doping element is, the better the conductivity of the ultramicro N-type silicon crystal material 10 is, but a proper amount of doping element can ensure the better conductivity of the ultramicro N-type silicon crystal material 10 and the better embedding capability of the ultramicro N-type silicon crystal material to active metal ions.
In some embodiments of the present application, the powder resistivity of the negative electrode composite material 100 is less than or equal to 2.5mΩ·cm. Illustratively, the negative electrode composite material 100 may have a powder resistivity of 1.4mΩ·cm, 1.5mΩ·cm, 1.6mΩ·cm, 1.7mΩ·cm, 1.8mΩ·cm, 1.9mΩ·cm, 2.0mΩ·cm, 2.1mΩ·cm, 2.2mΩ·cm, 2.3mΩ·cm, 2.4mΩ·cm, 2.5mΩ·cm, and the like.
The embodiment of the application also provides a preparation method of the negative electrode composite material, which is suitable for preparing the negative electrode composite material 100. The preparation method comprises the following steps:
introducing a certain amount of silicon source, doping source and carbon source into a heating device for heating, wherein the carbon source forms conductive carbon material, and the conductive carbon material is dispersed with an ultra-micro N-type silicon crystal material formed by in-situ reaction of the silicon source and the doping source so as to obtain a negative electrode composite material;
the negative electrode composite material comprises an ultrafine N-type silicon crystal material and a conductive carbon material, wherein the ultrafine N-type silicon crystal material is dispersed in the conductive carbon material; the outer surface of the negative electrode composite material particles is not exposed by the ultra-micro N-type silicon crystal material, and the D50 particle size of the ultra-micro N-type silicon crystal material is less than or equal to 5nm.
And introducing a silicon source, a doping source and a carbon source into the fluidized bed furnace so that the decomposed silicon source and the decomposed doping source can be co-deposited to generate an ultra-micro N-type silicon crystal material, and the ultra-micro N-type silicon crystal material is suspended in the fluidized bed furnace. At the moment, the carbon source is decomposed and deposited on the surface of the superfine N-type silicon crystal material, and along with continuous deposition of the conductive carbon material on the surface of the material unit, the superfine silicon crystal particles with the conductive carbon material deposition layer are continuously fused in the fluidized bed furnace, so that the negative electrode composite material provided by the embodiment of the application is finally formed.
The preparation method is simple to operate, high in process controllability and high in production efficiency, and is suitable for large-scale industrial preparation.
In the application, the silicon source and the doping source are gasified under the action of high temperature, or are directly doped with the gaseous silicon source and the gaseous doping source, so that gas phase reaction occurs among the silicon source, the doping source and the carbon source.
In some embodiments of the present application, the heating device is configured to heat a certain amount of silicon source, doping source, and carbon source, and at least includes the following steps: (1) preheating treatment: introducing a carbon source into the heating device; (2) heat treatment: replacing the carbon source with the silicon source and the doping source; (3) post-treatment: the silicon source is replaced with the carbon source. That is, during the preheating treatment, raw materials other than the silicon source and the doping source are introduced; in the heat treatment process, raw materials except carbon sources are introduced; in the post-treatment process, raw materials except a silicon source and a doping source are introduced. The preparation of the negative electrode composite material according to the steps can enable the ultrafine N-type silicon crystals to be better dispersed in the conductive carbon material, and further optimize the electrochemical performance of the negative electrode composite material.
In some embodiments of the present application, the amount of silicon source introduced into the heating device is gradually decreased during the heat treatment. At the moment, the mass content of the ultra-micro N-type silicon crystal material in the single negative electrode composite material is guaranteed to be gradually reduced from the center of the negative electrode composite material to the outer surface. In some embodiments, the decrementing is performed at a rate that decreases by 50wt.% per hour. At the moment, the mass content of the ultra-micro N-type silicon crystal material in the negative electrode composite material is more favorably adjusted to gradually decrease from the center of the negative electrode composite material to the outer surface.
In some embodiments of the present application, the silicon source may be a material well known to those skilled in the art. The silicon source includes, but is not limited to, siH 4 。
In some embodiments of the present application, the dopant source may be a material well known to those skilled in the art. The doping source includes, but is not limited to, a phosphine.
In some embodiments of the present application, the carbon source may be a material well known to those skilled in the art, and the carbon source may be in a gaseous state or a liquid state. Specifically, the carbon source includes, but is not limited to, acetylene.
In some embodiments of the present application, the conditions of the heat treatment are: treating at 400-2000 deg.c for 0.25-4 hr.
In some embodiments of the present application, the method further comprises presetting conductive carbon skeleton material in the heating device. That is, a solid skeletal carbon material is placed in a heating device prior to introducing other raw materials into the heating device. The skeleton carbon material has more pore structures, silicon elements and doping elements can be adsorbed and deposited in the skeleton carbon material to form an ultra-micro N-type silicon crystal material, and subsequently introduced carbon sources can be deposited in the skeleton carbon material to fill gaps so that the ultra-micro N-type silicon crystal material can be buried in the conductive carbon material. Thus, the production efficiency can be remarkably improved. In some embodiments, the conductive carbon backbone material includes, but is not limited to, activated carbon.
The embodiment of the application also provides a negative electrode plate with the negative electrode composite material 100 provided by the embodiment of the application.
The electrode plate has good multiplying power performance, cycle performance and safety performance.
In some embodiments of the present application, the negative electrode composite material provided in the first aspect of the present application may be formed on a negative electrode current collector (such as a copper foil), and then rolled and slit to obtain a negative electrode sheet. Specifically, the slurry containing the negative electrode composite material is coated on a negative electrode current collector, and the negative electrode plate is obtained after drying, rolling and slitting.
The embodiment of the application provides an electrochemical device, which is provided with a negative electrode plate.
The electrochemical device comprises a secondary battery, and the secondary battery has high rate capability, good cycle performance and high safety.
The secondary battery may be a liquid battery using a liquid electrolyte, or a semi-solid or solid battery using a semi-solid electrolyte or a solid electrolyte. In some embodiments, a secondary battery may include a positive electrode tab, the negative electrode tab described above, and a separator and an electrolyte disposed between the positive electrode tab and the negative electrode tab. In other embodiments, the secondary battery may include a positive electrode tab, a negative electrode tab, and a semi-solid electrolyte or a solid electrolyte disposed between the positive electrode tab and the negative electrode tab. In addition, when a semi-solid electrolyte or a solid electrolyte is used, a semi-solid electrolyte material or a solid electrolyte material may be contained in the positive electrode tab and the negative electrode tab.
In the application, the lithium battery can be assembled by the following method:
s01, in a glove box, sequentially stacking the positive electrode plate, the diaphragm and the negative electrode plate to prepare an electric core;
and S02, packaging the battery core by adopting an aluminum plastic film shell, and injecting electrolyte to obtain the battery with the battery capacity of 3-5 AH. The cell may be formed and then subjected to electrochemical performance testing.
Alternatively, the above lithium battery may be assembled by:
s01, in a glove box, aligning and placing a positive electrode plate with a solid or semi-solid electrolyte layer and a negative electrode plate to prepare an electric core; wherein the solid or semi-solid electrolyte layer is adjacent to the negative electrode plate;
and S02, packaging the battery cell to obtain the solid or semi-solid battery. The cell may be formed and then subjected to electrochemical performance testing.
In some embodiments of the application, the positive plate can be obtained by coating positive electrode slurry containing positive electrode active electrode materials, conductive agents and adhesives on a positive electrode current collector (such as aluminum foil), drying and tabletting. The positive electrode active material is a material well known to those skilled in the art, and may specifically be at least one of lithium iron phosphate, lithium titanate, lithium cobaltate, nickel manganese cobalt ternary, nickel cobalt aluminum ternary, and lithium-rich manganese-based material. The conductive agent is a material well known to those skilled in the art, and may specifically be at least one of carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene, and mixed conductive paste. The binder is a material well known to those skilled in the art, and may specifically be at least one of polyvinylidene fluoride, polyamide resin, polyacrylonitrile, sodium carboxymethyl cellulose, and styrene butadiene rubber.
In general, the aforementioned electrolytic solution contains an organic solvent, a lithium salt, and an additive; the above organic solvents, lithium salts and additives may all be materials well known to those skilled in the art. Illustratively, the organic solvent may be at least one of ethylene carbonate, ethylmethyl carbonate, ethylene carbonate, fluoroethylene carbonate, vinylene carbonate, tetraglyme, glyme, dimethyl ether, and 1, 3-dioxolane; the lithium salt may be at least one of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium bistrifluoromethylsulfonimide and lithium trifluorosulfonylimide; the additive may be at least one of fluoroethylene carbonate, vinylene carbonate and lithium nitrate.
In some embodiments of the present application, the separator is a material well known to those skilled in the art, and may be, for example, a polyethylene film, a polypropylene film, a polyethylene/polypropylene double-layer film, a polyethylene/polypropylene triple-layer film, or the like.
In some embodiments of the present application, the solid or semi-solid electrolyte is a material well known to those skilled in the art.
The following describes the technical scheme of the application in more detail by a plurality of specific embodiments.
Example 1
Will N 2 、SiH 4 、PH 3 、C 2 H 2 Introducing the mixture into a heating device-a fluidized bed furnace for reaction, wherein the specific process conditions are shown in table 1. The negative electrode composite material thus obtained was designated as S1. The D50 particle size of S1 is 9 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is 5nm.
Example 2
Activated carbon powder, N 2 、SiH 4 、PH 3 、C 2 H 2 Introducing the mixture into a heating device-a fluidized bed furnace for reaction, wherein the specific process conditions are shown in table 1. The negative electrode composite material thus obtained was designated as S2. The D50 particle size of S2 is determined to be 12 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is determined to be 2nm.
Example 3
Porous carbon powder, N 2 、SiH 4 、PH 3 、C 2 H 4 Introducing the mixture into a heating device-a fluidized bed furnace for reaction, wherein the specific process conditions are shown in table 1. The negative electrode composite material thus obtained was designated as S3. The D50 particle size of S3 is 15 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is 5nm.
Example 4
Acetylene black powder, N 2 、SiH 4 、PH 3 Toluene was introduced into a heating apparatus, a fluidized bed furnace, to carry out the reaction, and specific process conditions are shown in Table 1. The negative electrode composite material thus obtained was designated as S4. The D50 particle size of S4 is 10 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is 0.5nm.
Example 5
Porous carbon powder and CO 2 、SiH 4 、PH 3 、CH 4 Introducing the mixture into a heating device-a fluidized bed furnace for reaction, wherein the specific process conditions are shown in table 1. The negative electrode composite material thus obtained was designated as S5. The D50 particle size of S5 is 11 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is 0.2nm.
Example 6
Porous carbon powder, N 2 Ethyl silicate (T)EOS)、PH 3 、CH 4 The reaction was carried out in a heating apparatus-vacuum rotary kiln, and specific process conditions are shown in Table 1. The negative electrode composite material thus obtained was designated as S6. The D50 particle size of S5 is 13 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is 5nm.
Example 7
The only differences from example 1 are: in the heat treatment stage, 50wt.% SiH is reduced per hour 4 And (3) introducing a silicon source into the fluidized bed furnace. The D50 particle size of S7 is 9 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is 5nm.
To highlight the beneficial effects of the embodiments of the present application, the following comparative examples are now set forth.
Comparative example 1
Will N 2 、SiH 4 、C 2 H 2 Introducing the mixture into a heating device-a fluidized bed furnace for reaction, wherein the specific process conditions are shown in table 1. The negative electrode composite material thus obtained was designated DS1. The D50 particle size of DS1 is 9 mu m, and the D50 particle size of the ultra-micro N-type silicon crystal material is 5nm.
Comparative example 2
Silicon monoxide particles, N 2 、C 2 H 2 Introducing the mixture into a heating device-a fluidized bed furnace for reaction, wherein the specific process conditions are shown in table 1. The negative electrode composite material thus obtained was designated DS2. The D50 particle size of DS2 is 9 mu m, and the D50 particle size of nano silicon crystal grains contained in the material is 7nm (calculated by Debye-Scherrer formula after XRD test).
Comparative example 3
After ball milling and sand grinding N-type monocrystalline silicon particles, nano silicon powder with the D50 particle size of 100nm is prepared, then nano silicon powder, flake graphite and phenolic resin are introduced, and the prepared negative electrode composite material is denoted as DS3 through granulation and heat treatment. As a result, the D50 particle diameter of DS3 was 20. Mu.m, the mass percentage of silicon element in DS3 was 15%, and the volume concentration of phosphorus element was 1.6X10 16 atoms/cm 3 。
Secondary batteries with the negative electrode composite materials (negative electrode materials) produced in the above examples and comparative examples were produced:
(1) Preparing a negative electrode plate: the cathode composite materials (cathode materials), graphite and binder (SBR and polyacrylic acid in particular) prepared in each example and comparative example, and conductive agent (acetylene black and carbon nano tube in particular) are prepared according to the mass percentage of 5:95:10:5, adding the mixture into solvent-water, and fully stirring to obtain negative electrode slurry; and (3) coating a certain amount of negative electrode slurry on the surface of a negative electrode current collector-copper foil, and drying, rolling and cutting to obtain a negative electrode plate.
(2) Preparing a positive electrode plate: positive electrode active material-LiNi 0.8 Co 0.1 Mn 0.1 (NCM 811), binder-PVDF 5130 and conductive agent-super P are dissolved in N-methyl pyrrolidone (NMP) according to the mass ratio of 8.7:0.8:0.5, and the positive electrode slurry is obtained after the materials are fully stirred. And coating the positive electrode slurry on a positive electrode current collector-aluminum foil, and drying, rolling and cutting to obtain the positive electrode plate.
(3) Preparation of secondary battery: and alternately stacking a plurality of the negative electrode plates, the diaphragms and the positive electrode plates, and preparing the battery in a lamination mode, wherein the positive electrode plates and the negative electrode plates are alternately arranged, and adjacent positive electrode plates and negative electrode plates are separated by the diaphragms, so that a dry battery core is obtained. Placing the dry cell in an aluminum plastic film outer package, injecting electrolyte, vacuumizing and sealing, placing at 60 ℃ for 48 hours, pressurizing the layer at 60 ℃, secondarily packaging, exhausting and separating to obtain the laminated soft-package full cell with the capacity of 2.2 Ah. Each example cell was designated as S1-S7, and each comparative example cell was designated as DS1-DS3.
Correlation characterization:
(1) And carrying out transmission electron microscope scanning (Transmission Electron Microscope, TEM) test on each negative electrode composite material, observing the microscopic morphology of each negative electrode composite material, and measuring the D50 particle size of the ultra-micro N-type silicon crystal material in the negative electrode composite material.
(2) And performing energy spectrum (energy dispersive spectroscopy, EDS) surface scanning test on each negative electrode composite material, and performing semi-quantitative test on silicon element distribution inside the ultra-micro N-type silicon crystal material.
(3) The negative electrode composite materials prepared in each of examples and comparative examples were measured for powder resistivity: placing the powder to be tested into a specific container, applying 50MPa to maintain pressure for 10s, and measuring by a 4-probe method. The results are summarized in table 3.
(4) Electrochemical performance tests were performed on the above-described batteries S1 to S7, DS1 to DS3 with the negative electrode composites (negative electrode materials) of each example and comparative example. The method comprises the following steps:
(a) And (3) cyclic testing of the normal-temperature battery: the cells were subjected to a 1C/1C charge-discharge cycle test at 25℃and a voltage ranging from 4.2V to 3.0V, and the expansion rate and capacity retention rate of the cells after 200 cycles were recorded, and the results are summarized in Table 4. The test was continued and the cell expansion and capacity retention after 400 cycles were recorded and the results are summarized in table 4.
(b) High temperature battery cycle test: the cells were subjected to a 1C/1C charge-discharge cycle test at 45℃and a voltage ranging from 4.2V to 3.0V, and the expansion rate and capacity retention rate of the cells after 200 cycles were recorded, and the results are summarized in Table 4. The test was continued and the cell expansion and capacity retention after 400 cycles were recorded and the results are summarized in table 4.
(c) And (3) multiplying power performance test: the ratio of discharge capacities of the cells under 1C and 3C conditions was tested.
(5) And measuring the contents of silicon element and boron element in the negative electrode composite material by an inductively coupled plasma spectrometer (inductive coupled plasma emission spectrometer, ICP). And measuring the content of carbon element in the negative electrode composite material by adopting a carbon-sulfur analyzer. Wherein the B element is identified in wt% in the ICP test result (C wt ) It is in units of atoms/cm 3 The conversion relation between the components can be calculated by an empirical formula C wt ＝k×C nl Conversion, wherein k is generally 2×10 -23 -5×10 -22 The specific value of k needs to be determined according to the true density of the measured material.
(6) And (3) performing X-ray diffraction (XRD) test on each negative electrode composite material, performing peak-splitting fitting by applying a Schle formula, and semi-quantitatively testing each component and content to verify the element content test result obtained in the step (5).
Table 1 main process parameters of each of examples and comparative examples
TABLE 2 content of elements in the negative electrode composite materials of examples and comparative examples
| Sample numbering | Si(wt％) | C(wt％) | P(wt％) | P(atoms/cm 3 ) | O(wt％) |
| Example 1 | 52.4 | 41.8 | 0.7 | 7.16×10 19 | 5.1 |
| Example 2 | 53.0 | 42.4 | 0.1 | 1.02×10 19 | 4.5 |
| Example 3 | 52.2 | 42.2 | 0.3 | 3.07×10 19 | 5.3 |
| Example 4 | 52.7 | 41.9 | 0.7 | 7.16×10 19 | 4.7 |
| Example 5 | 52.4 | 41.8 | 1.2 | 1.23×10 20 | 4.6 |
| Example 6 | 52.1 | 42.0 | 1.0 | 1.02×10 20 | 4.9 |
| Example 7 | 36.3 | 55.1 | 0.8 | 6.15×10 19 | 7.8 |
| Comparative example 1 | 52.2 | 42.4 | 0.0 | 0 | 4.5 |
| Comparative example 2 | 39.8 | 9.6 | 0.0 | 0 | 50.6 |
| Comparative example 3 | 47.5 | 42.4 | 0.0 | 0 | 10.1 |
TABLE 3 powder resistivity of the negative electrode composites prepared in examples and comparative examples
Table 4 summary of the results after 200 cycles of charge and discharge of the batteries prepared in each example and comparative example
As can be seen from the data in tables 1 to 4, the negative electrode composite material provided in the examples of the present application shows superior electron conductivity properties compared to the comparative example material; when the anode composite material provided by the embodiment is applied to a battery, the multiplying power performance, normal temperature and high temperature cycle performance of the battery can be obviously optimized, and compared with the battery of the comparative example, at least one of the normal temperature battery expansion rate or the high temperature battery expansion rate of the S1-S7 battery is obviously lower than that of the battery of the comparative example, the high temperature cycle performance of the battery of the embodiment is particularly good, and the superiority of the anode composite material of the embodiment of the application is fully illustrated, so that the anode composite material can be used for providing an electrochemical device with better electrochemical performance. When the anode composite material meets the preferred conditions of the application, namely, the mass content of the ultrafine P-type silicon crystal material in the single anode composite material gradually decreases from the center to the outer surface of the anode composite material, the comprehensive performance of the battery S7 is obviously better under the condition that other parameters are similar, such as the embodiment 7 and the embodiment 4.
It should be noted that the O element of the anode composite material of the embodiment comes from the preparation environment, and has no obvious influence on the electrochemical performance of the material; the high oxygen content of comparative example 2 is brought about by the raw material silicon monoxide.
While the foregoing is directed to exemplary embodiments of the present application, it will be appreciated by those of ordinary skill in the art that numerous modifications and variations can be made thereto without departing from the principles of the present application, and such modifications and variations are to be regarded as being within the scope of the present application.
Claims (14)
1. The negative electrode composite material is characterized by comprising an ultrafine N-type silicon crystal material and a conductive carbon material, wherein the ultrafine N-type silicon crystal material is dispersed in the conductive carbon material; the outer surface of the negative electrode composite material particles is not exposed by the ultra-micro N-type silicon crystal material, and the D50 particle size of the ultra-micro N-type silicon crystal material is less than or equal to 5nm.
2. The anode composite of claim 1, wherein the anode composite is in a granular form, and the mass content of the ultrafine N-type silicon crystal material in the individual anode composite gradually decreases from the center of the anode composite to the outer surface.
3. The anode composite according to claim 2, wherein in the area where the ultrafine N-type silicon crystal material is distributed in the anode composite, the lowest mass concentration of silicon element is a and the highest mass concentration is B, wherein a is equal to or greater than 0.9B.
4. The anode composite of claim 1, wherein the mass percentage of elemental silicon in the anode composite is 25% -75%.
5. The anode composite of claim 1, wherein the constituent elements of the ultra-fine N-type silicon crystal material include elemental silicon and doping elements; the doping element comprises phosphorus element and/or arsenic element.
6. The anode composite of claim 5, wherein the doping element has an atomic volume concentration of less than or equal to 5 x 10 21 atoms/cm 3 。
7. The anode composite of claim 1, wherein the anode composite has a D50 particle size of less than or equal to 30 μιη.
8. The anode composite of any one of claims 1-7, wherein the anode composite has a powder resistivity of less than or equal to 2.5mΩ -cm.
9. The preparation method of the negative electrode composite material is characterized by comprising the following steps of:
introducing a certain amount of silicon source, doping source and carbon source into a heating device for heating, wherein the carbon source forms conductive carbon material, and the conductive carbon material is dispersed with an ultra-micro N-type silicon crystal material formed by in-situ reaction of the silicon source and the doping source so as to obtain a negative electrode composite material;
the negative electrode composite material comprises an ultrafine N-type silicon crystal material and a conductive carbon material, wherein the ultrafine N-type silicon crystal material is dispersed in the conductive carbon material; the outer surface of the negative electrode composite material particles is not exposed by the ultra-micro N-type silicon crystal material, and the D50 particle size of the ultra-micro N-type silicon crystal material is less than or equal to 5nm.
10. The method of claim 9, further comprising pre-positioning a conductive carbon skeleton material in the heating device.
11. The method according to claim 9, wherein the heating treatment is performed by introducing a certain amount of silicon source, doping source, and carbon source into a heating device, and the method comprises at least the following steps:
(1) Preheating: introducing a carbon source into the heating device;
(2) And (3) heat treatment: replacing the carbon source with the silicon source and the doping source;
(3) Post-treatment: the silicon source is replaced with the carbon source.
12. The method of claim 11, wherein the amount of silicon source introduced into the heating device is decreased during the heat treatment.
13. A negative electrode sheet, characterized in that it comprises a negative electrode composite material according to any one of claims 1-8.
14. An electrochemical device comprising the negative electrode tab of claim 13.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211230393.6A CN117810380A (en) | 2022-09-30 | 2022-09-30 | Negative electrode composite material and preparation method and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211230393.6A CN117810380A (en) | 2022-09-30 | 2022-09-30 | Negative electrode composite material and preparation method and application thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117810380A true CN117810380A (en) | 2024-04-02 |
Family
ID=90432129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211230393.6A Pending CN117810380A (en) | 2022-09-30 | 2022-09-30 | Negative electrode composite material and preparation method and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117810380A (en) |
-
2022
- 2022-09-30 CN CN202211230393.6A patent/CN117810380A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9911976B2 (en) | Negative electrode active material for secondary battery, conductive composition for secondary battery, negative electrode material comprising same, negative electrode structure and secondary battery comprising same, and method for manufacturing same | |
| US10333141B2 (en) | Silicon-silicon oxide-lithium composite material having nano silicon particles embedded in a silicon:silicon lithium silicate composite matrix, and a process for manufacture thereof | |
| EP3518328B1 (en) | Silicon-containing structure, method of preparing the same, carbon composite using the same, and electrode, lithium battery, and device each including the same | |
| Qian et al. | Two-step ball-milling synthesis of a Si/SiO x/C composite electrode for lithium ion batteries with excellent long-term cycling stability | |
| Kobayashi et al. | Silicon/soft-carbon nanohybrid material with low expansion for high capacity and long cycle life lithium-ion battery | |
| KR20100109483A (en) | Composite for electrode active material and secondary battery comprising using the same | |
| JP2013054958A (en) | Negative electrode material for nonaqueous electrolyte secondary battery, lithium ion secondary battery, and electrochemical capacitor | |
| JP2015527707A (en) | Graphene coated electrode | |
| Wei et al. | Porous micro-spherical LiFePO 4/CNT nanocomposite for high-performance Li-ion battery cathode material | |
| Yoon et al. | Critical dual roles of carbon coating in H2Ti12O25 for cylindrical hybrid supercapacitors | |
| Li et al. | Plate-like LiFePO4/C composite with preferential (010) lattice plane synthesized by cetyltrimethylammonium bromide-assisted hydrothermal carbonization | |
| KR101927414B1 (en) | Electro active material for secondary battery, conductive composition for secondary battery, cathode material, cathode structure and secondary battery comprising the same, and fabricating methods thereof | |
| Thirumal et al. | High performance Li-ion battery-type hybrid supercapacitor devices using antimony based composite anode and Ketjen black carbon cathode | |
| KR102176590B1 (en) | Method of preparing anode active material for rechargeable lithium battery and rechargeable lithium battery | |
| Youjie et al. | Lithium titanate anode for high-performance lithium-ion batteries using octadecylamine and folic acid-functionalized graphene oxide for fabrication of ultrathin lithium titanate nanoflakes and modification of binder | |
| Zhengwei et al. | A facile route for synthesis of LiFePO4/C cathode material with nano-sized primary particles | |
| Zhang et al. | Large-scale synthesis of Li 3 V 2 (PO 4) 3@ C composites by a modified carbothermal reduction method as cathode material for lithium-ion batteries | |
| Honggowiranto et al. | Characterization of LiFePO4 cathode by addition of graphene for lithium ion batteries | |
| CN115312711A (en) | Positive electrode composite material and preparation method and application thereof | |
| CN117810380A (en) | Negative electrode composite material and preparation method and application thereof | |
| CN117810381A (en) | Negative electrode composite material and preparation method and application thereof | |
| Andersen et al. | Production of Silicon Particles for High-Capacity Anode Material Yielding Outstanding Production Capacity | |
| Wang et al. | Enhanced electrochemical properties of LiFePO4–silicon composites as positive electrode materials fabricated using a solid-state method | |
| Li et al. | Optimization prelithiation current of silicon-oxygen anode for high specific energy li-ion cells | |
| Battery | Preparation of Tough, Binder-Free, and Self-Supporting LiFePO |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |