CN115966790A - Lithium iron phosphate battery and formation method thereof - Google Patents
Lithium iron phosphate battery and formation method thereof Download PDFInfo
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- CN115966790A CN115966790A CN202111174442.4A CN202111174442A CN115966790A CN 115966790 A CN115966790 A CN 115966790A CN 202111174442 A CN202111174442 A CN 202111174442A CN 115966790 A CN115966790 A CN 115966790A
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- lithium iron
- phosphate battery
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- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 74
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000010277 constant-current charging Methods 0.000 claims abstract description 54
- 238000007600 charging Methods 0.000 claims abstract description 31
- 238000002347 injection Methods 0.000 claims description 34
- 239000007924 injection Substances 0.000 claims description 34
- 239000007788 liquid Substances 0.000 claims description 17
- 230000032683 aging Effects 0.000 claims description 11
- 238000007599 discharging Methods 0.000 claims description 11
- 239000003792 electrolyte Substances 0.000 claims description 10
- 229910003002 lithium salt Inorganic materials 0.000 claims description 9
- 159000000002 lithium salts Chemical class 0.000 claims description 9
- 239000007773 negative electrode material Substances 0.000 claims description 9
- 239000003960 organic solvent Substances 0.000 claims description 9
- 239000007774 positive electrode material Substances 0.000 claims description 9
- 238000005516 engineering process Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 101150016402 fsn-1 gene Proteins 0.000 claims description 4
- 230000018109 developmental process Effects 0.000 claims description 3
- 238000000859 sublimation Methods 0.000 claims description 3
- 230000008022 sublimation Effects 0.000 claims description 3
- 101150058243 Lipf gene Proteins 0.000 claims description 2
- 230000005611 electricity Effects 0.000 claims description 2
- 239000012528 membrane Substances 0.000 claims 1
- 208000028659 discharge Diseases 0.000 description 10
- 238000005056 compaction Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- 239000010406 cathode material Substances 0.000 description 3
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 101100117236 Drosophila melanogaster speck gene Proteins 0.000 description 1
- 239000005955 Ferric phosphate Substances 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 206010027146 Melanoderma Diseases 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 229940032958 ferric phosphate Drugs 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 description 1
- 229910000399 iron(III) phosphate Inorganic materials 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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- 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
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- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a lithium iron phosphate battery and a formation method thereof. The formation method of the lithium iron phosphate battery comprises the following steps: sequentially carrying out (1) 0.01-0.02C constant current charging on the lithium iron phosphate battery to be formed for 0.5-2h; (2) charging at 0.05-0.1 ℃ for 1-1.5h with constant current; (3) charging for 0.4-2h at 0.1-0.2 ℃ under constant current; the compacted density of the lithium iron phosphate battery to be formed is more than 2.5g/cc. The formation method of the invention ensures the formation of a compact SEI film and shortens the formation time.
Description
Technical Field
The invention relates to a lithium iron phosphate battery and a formation method thereof.
Background
The lithium ion battery has the characteristics of high energy density, long cycle life and the like, is rapidly developed in recent years, and is widely applied to the fields of digital codes, automobiles, backup power sources, energy storage power stations and the like; the lithium iron phosphate is used as one of main anode materials of the lithium ion battery, and has the characteristics of long cycle life, high safety, low cost and the like; since lithium ion batteries are commercially available, safety accidents such as combustion and explosion are frequent; lithium iron phosphate, which has high safety, low cost and long cycle life, is receiving attention from various manufacturers, and the demand for lithium iron phosphate has also increased explosively. At present, the energy density of the lithium iron phosphate single battery reaches 180Wh/Kg, and is expected to break through 200Wh/Kg in the future; in order to increase the energy density as much as possible, increasing the compacted density of the positive electrode is a necessary choice. The technical approach for realizing high compaction (compaction density of more than 2.5 g/cc) of the nano lithium iron phosphate is as follows: making the particle size of the particles larger or mixing small particles into large particles; for lithium iron phosphate having low ionic and electronic conductivities, the presence of large particles reduces the first capacity exertion of the active material. The formation is to activate the active substance; reacting the carbonate substance with the negative electrode graphite to generate a layer of compact solid electrolyte interface film (SEI film) on the surface of the negative electrode graphite; the SEI film has ion conduction and electron insulation properties, and can prevent the occurrence of side reactions, reduce the loss of irreversible capacity, and improve cycle performance and safety performance.
In the prior art, a traditional high-temperature and negative-pressure formation mode is still adopted for a high-compaction lithium iron phosphate battery, and although the stable SEI film can be generated by small-current charging, the formation time is long and the efficiency is low; no improvement is made to the low first-time capacity exertion of the high-compaction lithium iron phosphate battery.
Publication number CN102891336B provides a formation method of a soft package lithium ion battery using lithium iron phosphate as an anode: the whole formation process comprises charging stage 2h-4h, storage stage 3d-6d, recharging stage, and storage stage 1d-3d. The whole process has overlong formation time and low formation efficiency.
Publication number CN112751098a provides a formation method of a lithium iron phosphate battery: charging for 10-16.7 h at 0.03-0.05C; standing and aging in an oven at 40-60 ℃; after the current of 0.1C-0.3C is charged to 3.65V, the current of 0.1C-0.3C is continuously used for discharging to 2.5V, and then the current of 0.5C-1C is used for charging and discharging for a week, and finally the 30% of electric quantity is kept. The formation process is complicated and takes long time.
Disclosure of Invention
The invention mainly aims to overcome the defects that the formation process of a high-compaction lithium iron phosphate battery in the prior art is long in time consumption, low in formation efficiency and low in first-time capacity exertion and black speck lithium precipitation is easily caused in the battery, and provides the lithium iron phosphate battery and the formation method thereof. The formation method of the invention ensures the formation of a compact SEI film, shortens the formation time and improves the production efficiency.
The invention mainly solves the technical problems through the following technical scheme.
The invention provides a formation method of a lithium iron phosphate battery, which comprises the following steps of sequentially carrying out the following steps on the lithium iron phosphate battery to be formed:
charging for 0.5-2h at a constant current of 0.01-0.02C in the step (1);
charging at a constant current of 0.05-0.1 ℃ for 1-1.5h;
charging at a constant current of 0.1-0.2C for 0.4-2h;
wherein the compacted density of the lithium iron phosphate battery to be formed is more than 2.5g/cc.
The inventor finds that a stable and compact SEI film can be formed while the formation time is shortened by specific low-current constant-current charging for a certain time aiming at a lithium iron phosphate battery with a certain compaction density. If the current for constant current charging in steps (1) to (3) is too large, it is difficult to form a stable SEI film, and if it is too small, the formation time is prolonged. The above-described effects of the present invention cannot be achieved unless the constant current charging is performed.
In the present invention, after the constant current charging in the steps (1) to (3), the total amount of electricity charged into the lithium iron phosphate battery to be formed is preferably 20 to 30%, for example, 25%.
In the present invention, the current of the constant current charging in the step (2) is not equal to the current of the constant current charging in the step (3).
In the step (1), the time of the constant current charging is preferably 1h to 2h.
In the step (1), the limiting voltage is preferably 3.2V during the constant current charging.
In the step (1), when the current of the constant current charging is 0.01C, the time of the constant current charging is preferably 2h.
In the step (1), when the current of the constant current charging is 0.02C, the time of the constant current charging is preferably 1h.
In the step (1), after the constant current charging, a still standing operation is preferably performed, and the still standing time is preferably 5 to 10min.
In the step (2), the limiting voltage is preferably 3.4V during the constant current charging.
In the step (2), when the current of the constant current charging is 0.05C, the time of the constant current charging is preferably 1h.
In the step (2), when the current of the constant current charging is 0.1C, the time of the constant current charging is preferably 1.5h.
In the step (2), after the constant current charging, a still standing operation is preferably performed, and the still standing time is preferably 5-10 min.
In the step (3), during the constant current charging, the limiting voltage is preferably 3.6V.
In the step (3), when the current of the constant current charging is 0.1C, the time of the constant current charging is preferably 1.8h.
In the step (3), when the current of the constant current charging is 0.2C, the time of the constant current charging is preferably 0.4h.
In the step (3), after the constant current charging, a still standing operation is preferably performed, and the still standing time is preferably 5-10 min.
In the invention, the compaction density of the lithium iron phosphate battery to be formed is preferably 2.5-2.7 g/cc.
In the invention, the rated capacity of the lithium iron phosphate battery to be formed can be 100Ah.
In the invention, the positive electrode material of the lithium iron phosphate battery to be formed can be a positive electrode material with the model number of A8-4G which is conventional in the field and preferably purchased from Wanrunun New energy science and technology development Limited company, or a positive electrode material with the model number of SHF-10P which is purchased from Jiangxi sublimation New Material Limited company.
In the invention, the negative electrode material of the lithium iron phosphate battery to be formed can be a conventional negative electrode material in the field, preferably a negative electrode material with a model of KAG-1N which is commercially available from Guangdong Kaiki New energy science and technology GmbH, or a negative electrode material with a model of FSN-1 which is commercially available from Shanghai fir science and technology GmbH.
In the present invention, the separator of the lithium iron phosphate battery to be formed may be conventional in the art, such as a PP separator. The PP separator has a gauge of 18L, for example. The PP separator has a thickness of, for example, 18um. The separator is specifically, for example, a PP separator commercially available from affordable new energy materials, inc.
In the present invention, the whole process of the formation method is preferably in a negative pressure environment, and the pressure of the negative pressure is preferably-0.06 MPa to-0.08 MPa, for example-0.07 MPa. The negative pressure is maintained in the whole process of the formation method, so that the gas generated in the formation process can be completely removed.
In the present invention, the lithium iron phosphate battery to be formed is generally subjected to liquid injection and standing in sequence before the step (1).
As known to those skilled in the art, the electrolyte is generally injected into the cell of the lithium iron phosphate battery. The electrolyte may be conventional in the art and generally includes a lithium salt and an organic solvent.
The organic solvent preferably comprises the following components in percentage by mass: 25% -30% of EC (ethylene carbonate), 55% -60% of EMC (ethyl methyl carbonate), 10% -20% of DMC (dimethyl carbonate) and 1.8% -2.5% of VC (vinylene carbonate), wherein% is the percentage of the mass of each component to the total mass of the electrolyte.
The lithium salt is, for example, liPF 6 。
In the electrolyte, the molar concentration of the lithium salt is preferably 0.7M to 1.1M, which refers to the molar concentration of the lithium salt in the organic solvent.
The electrolyte is, for example, an electrolyte available from the company TC-8087, a company of high and New materials, inc., tiancih, guangzhou.
The temperature of the injection liquid can be conventional in the art, and is preferably 20 to 28 ℃, for example, 25 ℃.
Wherein, in the liquid injection, the vacuum degree of the liquid injection port is preferably-0.06 MPa to-0.08 MPa, for example-0.07 MPa.
The injection amount of the injection liquid is preferably (3.6 × rated battery capacity) g. The rated capacity of the battery generally refers to the rated capacity of the lithium iron phosphate battery to be formed.
Wherein, the standing time is preferably 12 to 36 hours, and the standing temperature is preferably 40 to 50 ℃, such as 45 ℃.
In the present invention, step (4) is further performed after step (3), and said step (4) preferably comprises the steps of: charging at constant current of 0.1-0.2C for 10-30 s, discharging at constant current of 0.1-0.2C for 10-30 s, and circulating for 100-200 times.
In step (4), as known to those skilled in the art, the time of the constant current charging is generally equal to the time of the constant current discharging.
In the step (4), the time of the constant current charging is preferably 18 to 30s, for example, 18s.
The inventor finds that, in a further research and development process, the lithium iron phosphate battery after formation can improve the first coulombic efficiency, the first discharge gram capacity and the capacity retention rate of the lithium iron phosphate battery more significantly under a specific limiting voltage by the constant current from the step (1) to the step (3) in combination with the cycle number of constant current charging and discharging of the specific current in the step (4)
In the present invention, after the formation method, the secondary injection and the aging and standing are generally performed in this order. It is known to those skilled in the art that, when said step (4) is not performed, said secondary injection and said aging stand are performed after said step (3). When said step (4) is performed, it is performed after step (4).
Wherein the temperature of the secondary injection is preferably 20 to 28 ℃, for example, 25 ℃.
The injection amount of the secondary injection is preferably (0.4 × rated battery capacity) g.
Wherein, the aging and standing time is preferably 12-36 h, such as 24h. The temperature of the aging and standing is preferably 40 to 50 ℃ such as 45 ℃.
The electrolyte for the secondary injection is preferably as described above.
The invention also provides a lithium iron phosphate battery, which is prepared by the formation method of the lithium iron phosphate battery.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows: compared with the traditional technical scheme, the method greatly shortens the formation time, reduces the production energy consumption and improves the production efficiency while ensuring the compactness and stability of the SEI film.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the invention thereto. Experimental procedures without specifying specific conditions in the following examples were selected in accordance with conventional procedures and conditions, or in accordance with commercial instructions.
The lithium iron phosphate batteries used in examples 1 to 8 of the present invention below had a rated capacity of 100Ah.
The electrolyte used in the following embodiments 1 to 8 of the present invention includes a lithium salt and an organic solvent, wherein the organic solvent includes the following components by mass:
EC 25％-30％；
EMC 55％-60％；
DMC 10％-20％；
VC 1.8％-2.5％；
the lithium salt is LiPF 6 The molar concentration of the organic solvent is 0.7M-1.1M.
The compacted density of the lithium iron phosphate batteries of examples 1 to 8 according to the invention was 2.5g/cc.
The anode material of the lithium iron phosphate battery in the following examples 1 to 6 and 8 of the present invention is A8-4G, mo Run new energy science and technology development ltd. The cathode material used in example 7 was a cathode material of SHF-10P type in the new material for sublimation, inc.
The negative electrode material of lithium iron phosphate batteries 1 to 7 in the following examples of the present invention is KAG-1N, guangdong kaikin new energy science and technology ltd. The negative electrode material used in example 8 was FSN-1, a type of the shanghai fir technology ltd.
The specification of the PP separator for the iron phosphate lithium battery in the following examples 1 to 8 is 18L, the thickness is 18um, hui Jiang new energy materials limited company.
After the battery core of the ferric phosphate lithium battery in the following embodiments 1-8 is injected with liquid, standing for 36h at a high temperature of 45 ℃; then, the lithium iron phosphate battery is placed on formation equipment, and the vacuum of-0.07 MPa is kept at a liquid injection port; wherein the temperature of the liquid injection is 25 ℃, and the liquid injection amount during the liquid injection is 3.6 times of the rated capacity of the battery.
After the formation of the iron phosphate lithium battery in the following examples 1-8, the invention also needs to perform secondary injection and aging standing, wherein the injection temperature is 25 ℃, the injection amount of the secondary injection is 0.4 times of the rated capacity of the battery, the aging temperature is 45 ℃, and the aging standing time is 24h.
Example 1
The lithium iron phosphate battery is formed according to the following steps:
charging at a constant current of 0.02C for 1h, limiting the voltage to 3.2V, and standing for 5min; negative pressure is-0.07 MPa;
charging for 1h at a constant current of 0.05C, and limiting the voltage to 3.4V; standing for 5min; negative pressure is-0.07 MPa;
charging for 1.8h at a constant current of 0.1C, and limiting the voltage to 3.6V; standing for 5min; negative pressure is-0.07 MPa; a total of 25% of the charge was charged.
Step (4) charging at a constant current of 0.1C for 18s, then discharging at a constant current of 0.1C for 18s, and circulating for 100 times; the negative pressure is-0.07 MPa.
Example 2
The difference lies in that:
step (4) charging at a constant current of 0.1C for 18s, then discharging at a constant current of 0.1C for 18s, and circulating for 200 times; the negative pressure is-0.07 MPa. The rest is the same as example 1.
Example 3
The difference lies in that:
and (4) charging at a constant current of 0.1C for 30s, then discharging at a constant current of 0.1C for 30s, and circulating for 100 times at negative pressure of-0.07 MPa. The rest is the same as example 1.
Example 4
The difference lies in that:
charging at 0.01C for 2h under constant current, limiting the voltage to 3.2V, and standing for 5min; negative pressure is-0.07 MPa;
charging at a constant current of 0.1C for 1.5h, and limiting the voltage to 3.4V; standing for 5min; negative pressure is-0.07 MPa;
charging for 0.4h at a constant current of 0.2C, and limiting the voltage to 3.6V; standing for 5min; negative pressure is-0.07 MPa; a total of 25% of the charge was charged.
Step (4) charging at a constant current of 0.1C for 18s, then discharging at a constant current of 0.1C for 18s, and circulating for 100 times; the negative pressure is-0.07 MPa. The rest of the procedure was the same as in example 1.
Example 5
The difference from example 1 is that:
in this example, the charge and discharge cycle of step (4) in example 1 was not performed. The rest is the same as example 1.
Example 6
The difference from example 5 is that:
charging at a constant current of 0.02C for 35min, limiting the voltage to 3.65V, and standing for 5min; negative pressure is-0.07 MPa;
charging at a constant current of 0.05 ℃ for 70min, limiting the voltage to 3.65V, and standing for 5min; negative pressure is-0.07 MPa;
charging at a constant current of 0.1C for 60min, limiting the voltage to 3.65V, and standing for 5min; negative pressure is-0.07 MPa;
charging at a constant current of 0.18C for 70min, limiting the voltage to 3.65V, and standing for 5min; negative pressure is-0.07 MPa; a total of 38% of the charge was charged. And also no charge-discharge cycling step was performed, as in example 5.
Example 7
The difference from the example 1 is that the positive electrode material used in the lithium iron phosphate battery is SHF-10P. The rest is the same as example 1.
Example 8
The difference from the example 2 is that the cathode material used in the lithium iron phosphate battery is FSN-1. The rest is the same as example 1.
Effect example 1
The charge capacity of the lithium iron phosphate battery in examples 1 to 8 was recorded as C 1 ；
After the secondary liquid injection and sealing of the lithium iron phosphate battery, the primary discharge capacity is measured, and the measuring method comprises the following steps:
(1) Charging the battery to 3.65V at a constant current of 0.5C, converting to constant voltage for charging, and stopping the current at 0.05C; the charging capacity is denoted as C 2 ；
(2) Standing for 30min;
(3) The battery is discharged to 2.5V at constant current of 0.5C, and the discharge capacity is marked as C 3 (ii) a The discharge capacity in this step is the first discharge capacity.
First coulombic efficiency = C 3 /(C 1 +C 2 )*100％；
First discharge gram volume = (C) 3 Positive electrode active material mass) mAh/g, (positive electrode active material mass is the usage amount of lithium iron phosphate in the battery cell).
The test results are shown in table 1 below.
TABLE 1
Examples 1 to 8 each performed 4 replicates.
According to the results of table 1, the lithium iron phosphate batteries obtained by the formation method of the present invention in examples 1 to 8 form a compact and stable SEI film and reduce the formation time, because no black spot lithium deposition occurs in the fully charged negative electrode state of the lithium iron phosphate batteries after formation, the first coulombic efficiency is 90% or more, the first discharge gram capacity is 142mAh/g or more, and the capacity retention rate is 92% or more after 400 cycles.
Further, as can be seen from comparison of examples 1, 5 and 6, the lithium iron phosphate battery with higher first coulombic efficiency and first gram capacity and higher cycle stability can be obtained by combining a specific charge-discharge cycle mode under a specific limiting voltage in each step of constant current charging.
Claims (10)
1. A formation method of a lithium iron phosphate battery is characterized by comprising the following steps of sequentially carrying out the lithium iron phosphate battery to be formed:
charging for 0.5-2h at a constant current of 0.01-0.02C in the step (1);
charging at a constant current of 0.05-0.1 ℃ for 1-1.5h;
charging at a constant current of 0.1-0.2C for 0.4-2h;
wherein the compacted density of the lithium iron phosphate battery to be formed is more than 2.5g/cc.
2. The method for forming the lithium iron phosphate battery according to claim 1, wherein after the constant current charging from the step (1) to the step (3), the amount of electricity charged in the lithium iron phosphate battery is 20 to 30% in total, for example, 25%;
and/or the current of the constant current charging in the step (2) is not equal to the current of the constant current charging in the step (3);
and/or the current of the constant current charging in the step (1) is 1 h-2 h.
3. The method for forming the lithium iron phosphate battery according to claim 1, wherein in the step (1), during the constant current charging, the limiting voltage is 3.2V;
and/or, in the step (1), when the current of the constant current charging is 0.01C, the time of the constant current charging is 2h; or, in the step (1), when the current of the constant current charging is 0.02C, the time of the constant current charging is 1h;
and/or, after the constant current charging in the step (1), still standing; the standing time is preferably 5-10 min;
and/or, during the constant current charging in the step (2), the limiting voltage is 3.4V;
and/or, in the step (2), when the current of the constant current charging is 0.05C, the time of the constant current charging is 1h; or, in the step (2), when the current of the constant current charging is 0.1C, the time of the constant current charging is 1.5h;
and/or, after the constant current charging in the step (2), still standing; the standing time is preferably 5-10 min;
and/or, during the constant current charging in the step (3), limiting the voltage to be 3.6V;
and/or, in the step (3), when the current of the constant current charging is 0.1C, the time of the constant current charging is 1.8h; or, in the step (3), when the current of the constant current charging is 0.2C, the time of the constant current charging is 0.4h;
and/or, after the constant current charging in the step (3), still standing; the standing time is preferably 5 to 10min.
4. The method for forming a lithium iron phosphate battery according to claim 1, wherein the compacted density of the lithium iron phosphate battery to be formed is 2.5-2.7 g/cc.
5. The method for forming the lithium iron phosphate battery according to any one of claims 1 to 4, wherein the step (3) is further followed by a step (4), wherein the step (4) comprises the following steps: charging at a constant current of 0.1-0.2C for 10-30 s, discharging at a constant current of 0.1-0.2C for 10-30 s, and circulating for 100-200 times;
in the step (4), the time of the constant current charging is preferably equal to the time of the constant current discharging;
in the step (4), the time of the constant current charging is preferably 18 to 30s.
6. The method for forming the lithium iron phosphate battery according to claim 5, wherein the positive electrode material in the lithium iron phosphate battery to be formed is a positive electrode material with a model number of A8-4G in Wanrun New energy science and technology development Co., ltd, or is a positive electrode material with a model number of SHF-10P in Jiangxi sublimation New Material Co., ltd;
and/or the negative electrode material in the lithium iron phosphate battery to be formed is a negative electrode material with a model of KAG-1N in Guangdong Kaiki New energy science and technology Co., ltd, or is a negative electrode material with a model of FSN-1 in Shanghai fir science and technology Co., ltd;
and/or the diaphragm of the lithium iron phosphate battery to be formed is a PP diaphragm;
the thickness of the PP separator is preferably 18um; the specification of the PP diaphragm is preferably 18L; specifically, the material is a PP membrane with the specification of Hui Jiang, new energy materials gmbh.
7. The method for forming the lithium iron phosphate battery as claimed in claim 1, wherein the whole process of the method is in a negative pressure environment; the negative pressure is preferably between-0.06 MPa and-0.08 MPa, for example-0.07 MPa.
8. The method for forming the lithium iron phosphate battery according to claim 1, wherein the lithium iron phosphate battery to be formed is further subjected to liquid injection and standing in sequence before the step (1); the electrolyte for injection preferably includes a lithium salt and an organic solvent;
the organic solvent preferably comprises the following components in percentage by mass: EC 25% -30%, EMC 55% -60%, DMC 10% -20% and VC 1.8% -2.5%, wherein% is the percentage of the mass of each component to the total mass of the electrolyte; the lithium salt is, for example, liPF 6 The molar concentration of the lithium salt in the organic solvent is, for example, 0.7M to 1.1M;
wherein the temperature of the injection liquid is preferably 20-28 ℃, for example 25 ℃;
wherein, during the liquid injection, the vacuum degree of the liquid injection port is preferably-0.06 MPa to-0.08 MPa, such as-0.07 MPa;
the injection amount of the injection liquid is preferably 3.6 times of the rated capacity of the lithium iron phosphate battery to be formed, and the unit of the injection amount is g;
wherein the standing time is preferably 12-36 h; the temperature of the standing is preferably 40 to 50 ℃, for example 45 ℃.
9. The method for forming the lithium iron phosphate battery according to claim 5, wherein the step (3) or the step (4) is further followed by sequentially carrying out secondary liquid injection and aging standing;
wherein, the temperature of the secondary injection is preferably 20-28 ℃, such as 25 ℃;
the injection amount of the secondary injection is preferably 0.4 times of the rated capacity of the lithium iron phosphate battery to be formed, and the unit of the injection amount is g;
wherein, the aging and standing time is preferably 12-36 h, such as 24h; the temperature of the aging and standing is preferably 40 to 50 ℃ such as 45 ℃.
10. A lithium iron phosphate battery, characterized in that it is a lithium iron phosphate battery manufactured by the formation method of a lithium iron phosphate battery according to any one of claims 1 to 9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116995318A (en) * | 2023-09-25 | 2023-11-03 | 成都特隆美储能技术有限公司 | 3.2V formation process of lithium iron phosphate battery |
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| CN116995318A (en) * | 2023-09-25 | 2023-11-03 | 成都特隆美储能技术有限公司 | 3.2V formation process of lithium iron phosphate battery |
| CN116995318B (en) * | 2023-09-25 | 2023-12-01 | 成都特隆美储能技术有限公司 | 3.2V formation process of lithium iron phosphate battery |
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