CN117712462A - Lithium ion battery and preparation method thereof - Google Patents
Lithium ion battery and preparation method thereof Download PDFInfo
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- CN117712462A CN117712462A CN202311730383.3A CN202311730383A CN117712462A CN 117712462 A CN117712462 A CN 117712462A CN 202311730383 A CN202311730383 A CN 202311730383A CN 117712462 A CN117712462 A CN 117712462A
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- ion battery
- lithium ion
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title abstract description 10
- MRVHOJHOBHYHQL-UHFFFAOYSA-M lithium metaphosphate Chemical compound [Li+].[O-]P(=O)=O MRVHOJHOBHYHQL-UHFFFAOYSA-M 0.000 claims abstract description 40
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000011267 electrode slurry Substances 0.000 claims abstract description 21
- 239000007773 negative electrode material Substances 0.000 claims abstract description 20
- 239000011230 binding agent Substances 0.000 claims abstract description 16
- 239000006185 dispersion Substances 0.000 claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 10
- 239000011812 mixed powder Substances 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims abstract description 10
- 239000007788 liquid Substances 0.000 claims abstract description 8
- 239000006258 conductive agent Substances 0.000 claims abstract description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 9
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 9
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 9
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 9
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 7
- 239000007787 solid Substances 0.000 claims description 7
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 239000003575 carbonaceous material Substances 0.000 claims description 3
- 229910021382 natural graphite Inorganic materials 0.000 claims description 3
- FHVDTGUDJYJELY-UHFFFAOYSA-N 6-{[2-carboxy-4,5-dihydroxy-6-(phosphanyloxy)oxan-3-yl]oxy}-4,5-dihydroxy-3-phosphanyloxane-2-carboxylic acid Chemical compound O1C(C(O)=O)C(P)C(O)C(O)C1OC1C(C(O)=O)OC(OP)C(O)C1O FHVDTGUDJYJELY-UHFFFAOYSA-N 0.000 claims description 2
- 229920001661 Chitosan Polymers 0.000 claims description 2
- 229920002907 Guar gum Polymers 0.000 claims description 2
- 240000007472 Leucaena leucocephala Species 0.000 claims description 2
- 235000010643 Leucaena leucocephala Nutrition 0.000 claims description 2
- 229920002125 Sokalan® Polymers 0.000 claims description 2
- 229940072056 alginate Drugs 0.000 claims description 2
- 235000010443 alginic acid Nutrition 0.000 claims description 2
- 229920000615 alginic acid Polymers 0.000 claims description 2
- 239000006183 anode active material Substances 0.000 claims description 2
- 229940045110 chitosan Drugs 0.000 claims description 2
- 239000000665 guar gum Substances 0.000 claims description 2
- 235000010417 guar gum Nutrition 0.000 claims description 2
- 229960002154 guar gum Drugs 0.000 claims description 2
- 239000004584 polyacrylic acid Substances 0.000 claims description 2
- 239000000230 xanthan gum Substances 0.000 claims description 2
- 235000010493 xanthan gum Nutrition 0.000 claims description 2
- 229920001285 xanthan gum Polymers 0.000 claims description 2
- 229940082509 xanthan gum Drugs 0.000 claims description 2
- 239000002002 slurry Substances 0.000 abstract description 24
- 239000002245 particle Substances 0.000 abstract description 16
- 230000015572 biosynthetic process Effects 0.000 abstract description 15
- 238000005096 rolling process Methods 0.000 abstract description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052744 lithium Inorganic materials 0.000 abstract description 6
- 239000011248 coating agent Substances 0.000 abstract description 5
- 238000000576 coating method Methods 0.000 abstract description 5
- 239000000654 additive Substances 0.000 abstract description 3
- 230000000996 additive effect Effects 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 9
- 238000009826 distribution Methods 0.000 description 8
- 239000010408 film Substances 0.000 description 8
- 239000006230 acetylene black Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 239000013543 active substance Substances 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 230000014759 maintenance of location Effects 0.000 description 5
- 238000005054 agglomeration Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000002174 Styrene-butadiene Substances 0.000 description 3
- 239000006256 anode slurry Substances 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 229910003002 lithium salt Inorganic materials 0.000 description 3
- 159000000002 lithium salts Chemical class 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 229910013870 LiPF 6 Inorganic materials 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
- 239000006257 cathode slurry Substances 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- UEZVMMHDMIWARA-UHFFFAOYSA-N Metaphosphoric acid Chemical compound OP(=O)=O UEZVMMHDMIWARA-UHFFFAOYSA-N 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a lithium ion battery and a preparation method thereof. The negative electrode of the lithium ion battery comprises lithium metaphosphate. The preparation method of the lithium ion battery comprises the following steps: dry stirring a negative electrode material comprising a negative electrode active material, a conductive agent and lithium metaphosphate to form a mixed powder; dispersing an aqueous binder in water to form a binder dispersion; dispersing the mixed powder into the binder dispersion liquid, and then adding water for multiple times to continuously disperse to form negative electrode slurry; and coating the negative electrode slurry on a current collector to form a negative electrode. According to the lithium ion battery, the negative electrode contains lithium metaphosphate, so that the number of small particles of slurry is reduced, the viscosity of the slurry is reduced, and the rolling pressure is further reduced; meanwhile, the additive contains lithium, can be used as a prelithiation material, can react with HF in a battery in a formation process, consumes the HF, accelerates SEI formation, reduces loss of lithium ions in the battery, improves formation speed, improves material stability, and further improves battery performance.
Description
Technical Field
The invention relates to the field of chemical power supplies, in particular to a lithium ion battery and a preparation method thereof.
Background
In the manufacturing process of the lithium ion battery, after the pole piece is coated and dried, the peeling strength of the active substance and the current collector foil is very low, and the active substance and the foil are required to be rolled so as to enhance the bonding strength of the active substance and the foil, reduce the internal resistance of the battery and improve the performance of the battery. When a large amount of small-particle-size active substances exist in the negative electrode slurry, the viscosity of the slurry can be influenced, meanwhile, the slurry filtering difficulty and the pole piece rolling difficulty can be increased, the production efficiency and the production cost of enterprises are influenced, and the storage and the circulation performance of a battery can be reduced.
In the production process of the lithium ion battery, formation is an extremely important step, and the step mainly comprises the steps of carrying out a first charging process on the battery after the battery is injected with liquid, wherein active substances in the battery are activated in the first charging process, so that the lithium ion battery is activated; at the same time, the electrolyte solvent and lithium salt undergo side reaction to consume lithium ions in the battery, and form a layer of solid electrolyte phase interface (SEI) film on the surface of the negative electrode of the battery, wherein the main components are LiF and Li 2 CO 3 Etc. The SEI film can prevent side reaction from further generating, and further reduces the loss of lithium content in the battery, so that the SEI film has important influence on the initial capacity loss, cycle life, rate capability, safety and the like of the lithium ion battery, and the less and better the consumed lithium ions are when the complete SEI film is generated.
Disclosure of Invention
In order to solve the problems, the invention provides a lithium ion battery and a preparation method thereof.
The invention provides a lithium ion battery, wherein the negative electrode of the lithium ion battery comprises lithium metaphosphate.
The invention also provides a preparation method of the lithium ion battery, which comprises the following steps: dry stirring a negative electrode material comprising a negative electrode active material, a conductive agent and lithium metaphosphate to form a mixed powder; dispersing an aqueous binder in water to form a binder dispersion; dispersing the mixed powder into the binder dispersion liquid, and then adding water for a plurality of times to continuously disperse to form negative electrode slurry; and coating the negative electrode slurry on a current collector to form a negative electrode.
The lithium ion battery of the invention, the negative electrode comprises lithium metaphosphate (LiPO 3 As a flocculant), the particle size distribution in the anode slurry can be changed by firstly mixing lithium metaphosphate with an anode active material and a conductive agent through dry stirring and then forming the anode slurry, so that the number of small particles of the slurry is reduced, the viscosity of the slurry is reduced, and the rolling pressure is further reduced; meanwhile, the additive contains lithium, can be used as a prelithiation material, can react with HF in a battery in a formation process, consumes HF, accelerates SEI formation, reduces loss of lithium ions in the battery, improves formation speed, and also improves material stability (consumption of HF), thereby improving battery performance.
Drawings
Fig. 1 is a graph showing the distribution of particle diameters in the negative electrode pastes of example 1 and comparative example 1.
Fig. 2 is a graph of the cycle capacity retention rates of the batteries of example 1 and comparative example 1.
Detailed Description
The present invention will be described in detail with reference to the following embodiments.
The negative electrode of the lithium ion battery comprises lithium metaphosphate. When the lithium ion battery is prepared, firstly, a negative electrode material containing a negative electrode active material, a conductive agent and lithium metaphosphate is dried and stirred to form mixed powder; dispersing an aqueous binder in water to form a binder dispersion; dispersing the mixed powder into a binder dispersion liquid, and then adding water for multiple times to continuously disperse to form negative electrode slurry; and finally, coating the negative electrode slurry on a current collector to form a negative electrode. Lithium metaphosphate (LiPO) 3 ) The flocculant is mixed with the negative electrode active material and the conductive agent by dry stirring to form negative electrode slurry, so that small-particle-size particles in the negative electrode slurry are agglomerated, and the purpose of improving the particle size distribution of the slurry is achieved.
The added lithium metaphosphate reduces the small-particle-size powder in the slurry, and simultaneously, the agglomeration of large powder particles cannot be caused, so that the viscosity of the slurry can be reduced, the solid content of the slurry can be improved, and the solid content can be improved from the existing about 49-51% to 52-54%. When the negative electrode plate is prepared, if the particles of the negative electrode material are smaller, the volume of the negative electrode material is relatively larger, the higher the energy is required for pressing the negative electrode material to a specific thickness, and the higher the pressure is. The excessive rolling pressure causes the overvoltage of the specific position of the pole piece, specular reflection occurs under the light detected by the CCD, strong light is detected by equipment, wrong marking and rejection occur, the scrappage is increased, and lithium is easily separated from the battery at the overvoltage in the circulation process. According to the invention, the metaphosphoric acid is added into the cathode, so that small-particle-size powder in the slurry can be reduced, the volume of cathode materials with the same mass is smaller, the solid content of the slurry can be improved, meanwhile, the pressure used when the slurry is rolled to the same thickness is smaller, the overvoltage phenomenon can be avoided, the cycling stability of the battery is improved, and the service life of the battery is prolonged.
Meanwhile, since lithium metaphosphate itself contains lithium, the lithium metaphosphate can be used as a prelithiation material, and HF generated in the formation stage of the lithium ion battery can be consumed. In the prior art, in the formation stage of the lithium ion battery, an SEI film (the main component is LiF, lithium ions are consumed through electrolyte to form a thin film capable of blocking electrons and solvent molecules from passing through) is formed on the surface of a negative electrode, in the formation process, water molecules in the battery can react with the electrolyte to produce HF, if the water content is too high, the battery is swelled, and scrapping is increased. The process of the formation process is as follows:
LiPF 6 →LiF+PF 5
PF 5 +H 2 O→POF 3 +2HF
POF 3 +3Li 2 O→6LiF+P 2 O 5 (or Li) x POF y )
In the invention, since lithium metaphosphate is added into the cathode, the lithium metaphosphate can react with the generated HF in the formation stage, and the reaction is as follows:
LiPO 3 +HF→Li x H y PO 4 (or PO) x H y )+LiF
In the formation stage, lithium metaphosphate reacts with HF in the battery, and the main component LiF of the SEI film formed by HF generation is consumed, so that SEI formation can be accelerated, meanwhile, loss of lithium ions in the battery is reduced, and formation speed and first efficiency of the battery are improved; and the material stability can be improved and the battery performance can be improved due to the consumption of HF.
The mass content of lithium metaphosphate in the cathode is 0.1-1.5 percent based on 100 percent of the total mass of the cathode. After the negative electrode is added with lithium metaphosphate (taking 1% of solid content lithium metaphosphate as an example), D10 is increased by about 20%, and D10 is increased from about 7.14 mu m to 8.50 mu m; d50 increased by about 8%, from about 14.81 μm to 16.01 μm; d99 varied from about 41.97 μm to 42.1 μm, almost unchanged (as shown in fig. 1).
The negative electrode active material in the negative electrode may be a negative electrode active material commonly used in lithium ion batteries, and the negative electrode active material preferably contains a carbon material, such as, but not limited to, one or more of artificial graphite, natural graphite, carbon-coated composite materials thereof, and the like.
The water-based binder can be one or more selected from carboxymethyl cellulose, polyacrylic acid, alginate, chitosan, guar gum, xanthan gum and acacia. After the mixed powder is dispersed into the binder dispersion liquid, styrene-butadiene rubber can be further added to continuously and uniformly stir to form the negative electrode slurry in order to improve the uniform dispersion of the negative electrode material in the slurry. And finally, coating the negative electrode slurry on a current collector, and drying and rolling to form a negative electrode plate.
The invention is further described below by means of specific examples. These examples are merely exemplary and are not intended to limit the scope of the present invention in any way. In the following examples and comparative examples, reagents, materials and instruments used, unless otherwise specified, were commercially available.
Example 1
(1) Preparation of negative electrode
The mass ratio is 96:1:1:1:1 weighing commercial artificial graphite, acetylene black, CMC (carboxymethyl cellulose), SBR (styrene butadiene rubber) and lithium metaphosphate (LiPO) 3 )。
Dispersing CMC with pure water, and stirring for 2 hr to obtain CMC dispersion. After stirring artificial graphite, acetylene black and lithium metaphosphate for 30 minutes, adding a proper amount of CMC dispersion liquid for dispersion for 2 hours, then adding water for 2 times, dispersing for 1 hour after each time of water addition, adding styrene-butadiene rubber into the slurry until the solid content reaches about 53%, and stirring for 1 hour to obtain the negative electrode slurry.
The cathode slurry is coated on the two sides of the copper foil by a coater to fix the surface density, and the surface density is 170g/m 2 Rolling to 130 μm with a roll press under a roll pressure of (50-70) T, and cutting into negative electrode pieces with a die cutter.
(2) Preparation of the Positive electrode
The mass ratio is 98:1:1, weighing lithium iron phosphate, PVDF (polyvinylidene fluoride) and acetylene black.
Mixing PVDF, acetylene black and lithium iron phosphate powder, stirring for 30 minutes, adding NMP (N-methyl pyrrolidone) to adjust the solid content to about 63%, and dispersing for 6 hours to obtain the anode slurry.
The positive electrode slurry is coated on carbon-coated aluminum foil with fixed surface density by a coater, and is coated on two sides, wherein the surface density is 360g/m 2 Rolling to 170 μm by a roll squeezer, rolling to a pressure (70-100) T, and cutting into positive pole pieces by a die cutter.
(3) Battery assembly
PP is selected as a diaphragm, a lithium battery diaphragm is placed between the prepared positive and negative pole pieces, a winding machine is used for winding and forming, then a tab is welded, a battery shell is placed, the tab and a battery shell post are welded, and then electrolyte is injected (lithium salt is LiPF 6 Solvent volume ratio 1:1:1ec, EMC and DEC, lithium salt concentration 1 mol/L) to give battery B1.
Example 2
Negative electrode raw material artificial graphite, acetylene black, CMC, SBR and lithium metaphosphate (LiPO) 3 ) The mass ratio of (2) is 96.9:1:1:1:0.1. other procedures were the same as in example 1 to obtain battery B2.
Example 3
Negative electrode raw material artificial graphite, acetylene black, CMC, SBR and lithium metaphosphate (LiPO) 3 ) The mass ratio of (2) is 95.5:1:1:1:1.5. other procedures were the same as in example 1 to obtain battery B3.
Comparative example 1
The other procedure for forming the negative electrode slurry was the same as in example 1, except that lithium metaphosphate was not used as the negative electrode material. The rolling pressure in the process of forming the negative electrode sheet was (70-100) T, and the negative electrode sheet was rolled to a thickness of 130. Mu.m. And cutting to form the negative plate.
The preparation of the positive electrode sheet and the assembly process of the battery were the same as in example 1, to obtain a battery DB1.
Performance tests were performed on batteries B1, B2, B3 and DB1 prepared in examples 1 to 3 and comparative example 1.
Performance testing
(1) Negative electrode slurry particle size test
Particle size distribution measurements were made using a Mastersizer3000 laser particle sizer for the negative electrode slurries prepared in example 1 and comparative example 1. The measurement results are shown in FIG. 1 (volume distribution diagram of slurry particle diameter).
(2) Negative electrode slurry viscosity test
Viscosity measurements were performed using a Brookfield thermostatted viscometer for the negative electrode pastes prepared in example 1 and comparative example 1.
(3) Battery initial efficiency test
And placing the formed battery in a 25 ℃ incubator, connecting a battery pole with a charging device, then charging to 3.65V constant voltage with 0.3C constant current until the current is less than 0.05C, discharging to 2.5V with 0.3C, extracting the charging process capacity C1 and the discharging process capacity C2, and calculating the initial efficiency of the battery to be IC=C2/C1.100 percent.
(4) Cycle performance test
And (3) charging the lithium ion battery prepared by the method to 3.65V at a 1C multiplying power in a constant temperature cabinet at 25 ℃, then trickling charging to 0.05C, discharging to 2.5V at the 1C multiplying power, performing full charge discharge cycle test, and observing the discharge capacity retention rate of the battery after 1000 cycles. A graph of capacity retention of the batteries of example 1 and comparative example 1 is shown in fig. 2.
The data of the above test are shown in table 1.
TABLE 1
Fig. 1 shows the distribution of the particle diameters of the anode materials in the anode pastes of example 1 and comparative example 1. When lithium metaphosphate exists in the slurry, the left-hand grain curve of the peak value moves to the right, which means that the number of small grains in the slurry is obviously reduced, the whole curve does not move to the right, the grain agglomeration in the slurry only occurs in small grains, and large grain agglomeration does not occur, which means that the grain size distribution in the slurry is more concentrated, and meanwhile, the large grain agglomeration is not caused, so that grains and scratches of the pole piece are generated after coating.
As can be seen from the data shown in table 1, as lithium metaphosphate is added, the numerical value of particles (D50) in the slurry is changed from small to large, the viscosity of the slurry is also sequentially reduced, and the capacity is correspondingly increased after initial effect and circulation, which indicates that lithium metaphosphate can change the particle size distribution of materials in the cathode slurry, promote the generation of SEI film of the battery and improve the initial effect and circulation stability of the battery; however, the higher the addition amount of lithium metaphosphate is, the better, and when the addition amount exceeds 1%, the viscosity of the slurry is reduced correspondingly, and the initial efficiency and the capacity retention rate are reduced, which may be related to the slow down of the kinetics of lithium ion intercalation and deintercalation caused by the excessive addition of lithium metaphosphate and the excessive particle size of the slurry.
As can be seen from fig. 2, the capacity retention rate of the battery added with a proper amount of lithium metaphosphate is obviously higher than that of the battery which is not added, and the main reason is that the additive can react with HF generated in the battery circulation process, consume HF and form a stable SEI film, so that the damage to the electrode structure caused by the erosion of electrolyte and HF in the circulation process is reduced, and the service life of the battery is further prolonged.
The preferred embodiments of the invention disclosed above are intended only to assist in the explanation of the invention. The preferred embodiments are not exhaustive or to limit the invention to the precise form disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best understand and utilize the invention. The invention is limited only by the claims and the full scope and equivalents thereof.
Claims (10)
1. A lithium ion battery, wherein the negative electrode of the lithium ion battery comprises lithium metaphosphate.
2. The lithium ion battery according to claim 1, wherein the lithium metaphosphate content in the negative electrode is 0.1-1.5% by mass based on 100% by mass of the negative electrode.
3. The lithium ion battery of claim 1, wherein the negative electrode comprises a negative electrode active material comprising a carbon material.
4. The lithium ion battery of claim 3, wherein the negative electrode active material comprises one or more of artificial graphite, natural graphite, and carbon-coated material.
5. A method for preparing a lithium ion battery, comprising:
dry stirring a negative electrode material comprising a negative electrode active material, a conductive agent and lithium metaphosphate to form a mixed powder;
dispersing an aqueous binder in water to form a binder dispersion;
dispersing the mixed powder into the binder dispersion liquid, and then adding water for a plurality of times to continuously disperse to form negative electrode slurry; and
The negative electrode slurry is coated on a current collector to form a negative electrode.
6. The method according to claim 5, wherein the solid content of the negative electrode slurry is 52wt% to 54wt%.
7. The method according to claim 5, wherein the amount of the lithium metaphosphate is 0.1 to 1.5% of the total mass of the negative electrode, based on 100% of the total mass of the negative electrode.
8. The production method according to claim 5, wherein the anode includes an anode active material including a carbon material; preferably, the negative active material includes one or more of artificial graphite, natural graphite, and carbon-coated material.
9. The method according to claim 5, wherein the aqueous binder is one or more selected from the group consisting of carboxymethyl cellulose, polyacrylic acid, alginate, chitosan, guar gum, xanthan gum, and acacia.
10. The method according to claim 5, wherein the mixed powder is dispersed in the binder dispersion liquid, and styrene-butadiene rubber is further added to form a negative electrode slurry.
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| CN202311730383.3A CN117712462A (en) | 2023-12-15 | 2023-12-15 | Lithium ion battery and preparation method thereof |
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