CN116525984A - Pre-charge formation method and preparation method of battery - Google Patents
Pre-charge formation method and preparation method of battery Download PDFInfo
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- CN116525984A CN116525984A CN202310750204.6A CN202310750204A CN116525984A CN 116525984 A CN116525984 A CN 116525984A CN 202310750204 A CN202310750204 A CN 202310750204A CN 116525984 A CN116525984 A CN 116525984A
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- 238000000034 method Methods 0.000 title claims abstract description 44
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 39
- 238000002360 preparation method Methods 0.000 title claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 4
- 229910052744 lithium Inorganic materials 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- ADKPKEZZYOUGBZ-UHFFFAOYSA-N [C].[O].[Si] Chemical compound [C].[O].[Si] ADKPKEZZYOUGBZ-UHFFFAOYSA-N 0.000 claims description 3
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 3
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 claims description 3
- 229910002804 graphite Inorganic materials 0.000 claims description 3
- 239000010439 graphite Substances 0.000 claims description 3
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 claims description 3
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 3
- 229910002102 lithium manganese oxide Inorganic materials 0.000 claims description 3
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 claims description 3
- VLXXBCXTUVRROQ-UHFFFAOYSA-N lithium;oxido-oxo-(oxomanganiooxy)manganese Chemical compound [Li+].[O-][Mn](=O)O[Mn]=O VLXXBCXTUVRROQ-UHFFFAOYSA-N 0.000 claims description 3
- URIIGZKXFBNRAU-UHFFFAOYSA-N lithium;oxonickel Chemical compound [Li].[Ni]=O URIIGZKXFBNRAU-UHFFFAOYSA-N 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- 230000000052 comparative effect Effects 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical group O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- -1 lithium hexafluorophosphate Chemical compound 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- 229910011328 LiNi0.6Co0.2Mn0.2O2 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-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
- 239000010405 anode material Substances 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005303 weighing Methods 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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
-
- 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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
- H01M10/446—Initial charging measures
-
- 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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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to the technical field of batteries, and discloses a battery pre-charge formation method and a preparation method, wherein the method comprises the following steps: pre-charging the battery with a first current until the voltage of the battery reaches a pre-charging cut-off voltage to obtain a pre-charged battery; continuously charging the battery after the pre-charging with a second current until the voltage of the battery reaches the full-charge voltage; the current value of the first current is not higher than 0.2C, and the pre-charge cut-off voltage is the full battery voltage corresponding to the condition that the negative electrode voltage of the battery is not higher than 0.2V. The pre-charge formation method can effectively improve the stability of the SEI film, and further improve the cycle stability of the battery.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a battery pre-charge formation method and a battery preparation method.
Background
The energy density and cycle life of a battery are important indicators for evaluating the performance of the battery. For example, for lithium ion batteries, the current energy density of lithium ion batteries has approached its theoretical limit, and thus, increasing the cycle life of lithium ion batteries has become a research hotspot in the industry.
The cycle life of a battery is affected by various factors, among which the quality of an SEI film formed on the surface of a negative electrode is one of the key factors affecting the cycle life of a battery. The SEI film is a thin layer of solid substance with conducting and electronic insulating properties generated after the reduction reaction of the electrolyte on the surface of the negative electrode. The SEI film with complete structure can effectively prevent the electrolyte from further reduction and ensure the smooth deintercalation in the cathode. If the structure of the SEI film is damaged, the electrolyte is caused to continuously perform a reduction reaction on the surface of the negative electrode, which not only consumes active lithium to cause capacity loss of the battery, but also causes internal impedance of the battery to continuously rise, so that the rate performance and discharge power of the battery are reduced.
The SEI film is formed in the first charge process of the battery, which is also called pre-charge-formation in the battery field. The pre-charge-formation refers to charging the battery with a small current in a certain voltage interval, thereby improving the quality of the SEI film, and then increasing the charging current and continuously charging for a predetermined period of time. Current research suggests that low current charging contributes to the formation of an SEI film that is structurally complete, uniform and dense, while high current charging results in a rough and loose SEI film structure. However, in actual production, continuous use of low-current charging will result in low production efficiency and increase in equipment, time and labor costs. Therefore, under the condition of not affecting the quality of the SEI film, the determination of the cut-off voltage of the small-current charge has important significance.
In the pre-charge-formation method commonly used at present, the formation voltage of an SEI film is identified by analyzing a capacity-voltage differential curve of battery charge, and meanwhile, the cut-off voltage of SEI film growth is determined according to the gas production characteristics of the battery, so that the cut-off voltage of small-current charge is determined, pre-charge-formation is performed based on the cut-off voltage, in particular, small-current charge is adopted before the cut-off voltage is reached, and large-current charge is adopted after the cut-off voltage is reached.
However, in the course of implementing the present invention, the inventors found that the stability of the SEI film formed by the above-described pre-charge-formation method is still poor, resulting in poor cycle stability of the battery.
Disclosure of Invention
In view of the above, the present invention provides a method for pre-charge formation and a method for preparing the same, so as to solve the problems of poor stability of an SEI film formed after pre-charge formation and poor cycle stability of a battery in the related art.
In a first aspect, the present invention provides a method for pre-charge formation of a battery, comprising the steps of:
pre-charging the battery with a first current until the voltage of the battery reaches a pre-charging cut-off voltage to obtain a pre-charged battery;
continuously charging the battery after the pre-charging with a second current until the voltage of the battery reaches the full-charge voltage;
the current value of the first current is not higher than 0.2C, and the pre-charge cut-off voltage is the full battery voltage corresponding to the condition that the negative electrode voltage of the battery is not higher than 0.2V.
In the related art, a formation voltage of an SEI film is recognized by analyzing a capacity-voltage differential curve of battery charging, and at the same time, a cut-off voltage of SEI film growth is determined according to a gassing characteristic of a battery, thereby determining a cut-off voltage of low current charging, and pre-charge-formation is performed based on the cut-off voltage. And related researches in the field show that the formation and reconstruction of the SEI film mainly occur in a voltage interval of 0.8V-0.2V (vs Li/Li+) of the negative electrode voltage, so that when the negative electrode voltage is still in the interval, the maintenance of low-current charge helps to significantly improve the stability of the SEI film. However, the inventors found that the control of the negative electrode voltage is remarkably neglected in determining the cutoff voltage of the low current charge in the related art, resulting in the negative electrode voltage still being 0.8V to 0.2V (vs Li/Li) + ) The high current charge is introduced in the voltage interval of (2), which reduces the stability of the SEI film, thereby resulting in poor cycle stability of the battery.
In the pre-charge formation method provided by the invention, the full battery voltage corresponding to the negative electrode voltage of the battery is used as the pre-charge cutoff voltage when the negative electrode voltage of the battery is not more than 0.2V, and the battery is charged by adopting the first current (small current) not more than 0.2C before the pre-charge cutoff voltage, so that the battery can be ensured to be in a small-current charging state when the SEI film is formed and/or reconstructed, the stability of the SEI film can be effectively improved, and the cycle stability of the battery is further improved.
In an alternative embodiment, the current value of the second current is greater than the current value of the first current.
In the pre-charge formation method provided by the invention, after the first current is charged to the pre-charge cut-off voltage, the second current with a larger current value than the first current is used for continuous charging, so that the pre-charge-formation efficiency can be improved through high-current charging under the condition of avoiding the SEI film forming and/or reconstructing process, namely, the pre-charge-formation efficiency is improved under the condition of not affecting the SEI film stability.
In an alternative embodiment, the current value of the second current is not lower than 0.1C. At this time, the continuous charging process can significantly improve the efficiency of the pre-charging-formation, and has less influence on the stability of the SEI film.
In an alternative embodiment, the determining of the precharge cutoff voltage includes:
charging a three-electrode cell with a third current, wherein the three-electrode cell comprises a positive electrode, a negative electrode and a reference electrode;
when the voltage of the negative electrode relative to the reference electrode is not higher than 0.2V, the full cell voltage of the positive electrode relative to the negative electrode is determined as the precharge cutoff voltage.
In an alternative embodiment, the third current has a current value of 0.01C to 5C.
In an alternative embodiment, the battery consists of the same kind of cells as the three-electrode cells.
In an alternative embodiment, in the three-electrode cell, the positive electrode includes at least one of a lithium nickel cobalt manganese oxide positive electrode, a lithium iron phosphate positive electrode, a lithium cobalt oxide positive electrode, a lithium manganese oxide positive electrode, and a lithium nickel oxide positive electrode;
the negative electrode comprises at least one of a graphite negative electrode, a silicon oxide negative electrode, a silicon carbon negative electrode and a silicon oxygen carbon negative electrode;
the reference electrode comprises a lithium-plated copper wire electrode and/or a lithium electrode.
In an alternative embodiment, in the battery, the formation process and/or the reconstruction process of the negative electrode SEI film occur in a region of 0.2V or more of the negative electrode voltage.
In a second aspect, the invention also provides a preparation method of the battery, which comprises the pre-charge formation method.
In a third aspect, the invention also provides a battery prepared by the preparation method.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments, but are not intended to limit the scope of the invention, and any product that is the same or similar to the present invention, either in light of the present invention or by combining the present invention with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
In order to solve the problems in the related art described above, according to a first aspect of the present invention, there is provided a pre-charge formation method of a battery, comprising the steps of:
pre-charging the battery with a first current until the voltage of the battery reaches a pre-charging cut-off voltage to obtain a pre-charged battery;
continuously charging the battery after the pre-charging with a second current until the voltage of the battery reaches the full-charge voltage;
the current value of the first current is not higher than 0.2C, and the pre-charge cut-off voltage is the full battery voltage corresponding to the condition that the negative electrode voltage of the battery is not higher than 0.2V.
In the related art, a formation voltage of an SEI film is recognized by analyzing a capacity-voltage differential curve of battery charging, and at the same time, a cut-off voltage of SEI film growth is determined according to a gassing characteristic of a battery, thereby determining a cut-off voltage of low current charging, and pre-charge-formation is performed based on the cut-off voltage. And related researches in the field show that the formation and reconstruction of the SEI film mainly occur in a voltage interval of 0.8V-0.2V (vs Li/Li+) of the negative electrode voltage, so that when the negative electrode voltage is still in the interval, the maintenance of low-current charge helps to significantly improve the stability of the SEI film. However, the inventors found that the control of the negative electrode voltage is remarkably neglected in determining the cutoff voltage of the low current charge in the related art, resulting in the negative electrode voltage still being 0.8V to 0.2V (vs Li/Li) + ) Introducing a large current charge in the voltage range of (2)And, this may lower the stability of the SEI film, thereby resulting in poor cycle stability of the battery.
In the pre-charge formation method provided by the invention, the full battery voltage corresponding to the negative electrode voltage of the battery being 0.2V is taken as the pre-charge cutoff voltage, and the battery is charged by adopting the first current (small current) which is not higher than 0.2C before the pre-charge cutoff voltage, so that the battery can be ensured to be in a small-current charging state when the SEI film is formed and/or reconstructed, the stability of the SEI film can be effectively improved, and the cycle stability of the battery is further improved.
In an alternative embodiment, the current value of the second current is greater than the current value of the first current.
In the pre-charge formation method provided by the invention, after the first current is charged to the pre-charge cut-off voltage, the second current with a larger current value than the first current is used for continuous charging, so that the pre-charge-formation efficiency can be improved through high-current charging under the condition of avoiding the SEI film forming and/or reconstructing process, namely, the pre-charge-formation efficiency is improved under the condition of not affecting the SEI film stability.
In an alternative embodiment, the current value of the second current is not lower than 0.1C. Preferably, the current value of the second current may be 0.1C to 2C. At this time, the continuous charging process can significantly improve the efficiency of the pre-charging-formation, and has less influence on the stability of the SEI film.
For example, the current value of the first current may be 0.05C, and the current value of the second current may be 0.15C or 0.3C.
In an alternative embodiment, the determining of the precharge cutoff voltage includes:
charging a three-electrode cell with a third current, wherein the three-electrode cell comprises a positive electrode, a negative electrode and a reference electrode;
when the voltage of the negative electrode relative to the reference electrode is not higher than 0.2V, the full cell voltage of the positive electrode relative to the negative electrode is determined as the precharge cutoff voltage.
In an alternative embodiment, the third current has a current value of 0.01C to 5C. The current value of the third current may be, for example, 0.1C.
In an alternative embodiment, the battery consists of the same kind of cells as the three-electrode cells.
In an alternative embodiment, in the three-electrode cell, the positive electrode includes at least one of a lithium nickel cobalt manganese oxide positive electrode, a lithium iron phosphate positive electrode, a lithium cobalt oxide positive electrode, a lithium manganese oxide positive electrode, and a lithium nickel oxide positive electrode;
the negative electrode comprises at least one of a graphite negative electrode, a silicon oxide negative electrode, a silicon carbon negative electrode and a silicon oxygen carbon negative electrode;
the reference electrode comprises a lithium-plated copper wire electrode and/or a lithium electrode.
In an alternative embodiment, in the battery, the formation process and/or the reconstruction process of the negative electrode SEI film occur in a region of 0.2V or more of the negative electrode voltage.
In a second aspect, the invention also provides a preparation method of the battery, which comprises the pre-charge formation method.
In a third aspect, the invention also provides a battery prepared by the preparation method.
The invention is described in further detail below in connection with specific examples which are not to be construed as limiting the scope of the invention as claimed.
Preparation example 1
The soft-package battery cell is prepared according to the following method:
(1) According to nickel cobalt lithium manganate (LiNi 0.6 Co 0.2 Mn 0.2 O 2 ): conductive carbon black: polyvinylidene fluoride=96.3: 2.5:1.2, weighing raw materials according to the weight ratio, then adding the raw materials into N-methyl pyrrolidone, and uniformly stirring to prepare positive electrode material slurry with the solid content of 70%; taking aluminum foil as a positive electrode current collector, sequentially coating, drying and die-cutting the positive electrode material slurry to obtain the aluminum foil-aluminum composite material with the compacted density of 3.5g/cm 3 Is a positive electrode sheet of (a);
(2) According to artificial graphite: conductive carbon black: sodium carboxymethyl cellulose: styrene butadiene rubber = 95.7:1:0.3:3 weight ratio of raw materials, and then adding into deionized waterUniformly stirring to prepare anode material slurry with the solid content of 50%; the copper foil is taken as a negative electrode current collector, the negative electrode material slurry is sequentially coated, dried and die-cut, and the compacted density of 1.6g/cm is prepared 3 Is a negative electrode sheet of (a);
(3) 1mol/L lithium hexafluorophosphate solution (the solvent is ethylene carbonate, diethyl carbonate, methyl ethyl carbonate and mixed solution of the ethylene carbonate and the methyl ethyl carbonate according to the volume ratio of 1:1:1) is used as electrolyte, polyethylene is used as a diaphragm, and the positive plate and the negative plate are taken to assemble the soft-package battery cell of 5.2 Ah.
Preparation example 2
The three-electrode cell was prepared as follows:
the soft-package battery cell prepared in preparation example 1 is taken, and a lithium-plated copper wire is implanted to serve as a reference electrode to prepare a three-electrode battery cell.
Example 1
The three-electrode cell prepared in preparation example 2 was charged as follows to determine the pre-charge cut-off voltage of the soft pack cell prepared in preparation example 1:
(1) Taking the three-electrode cell prepared in preparation example 2, charging the three-electrode cell with a current of 0.1C at low current, and monitoring the voltage of the negative electrode relative to the reference electrode and the full-cell voltage of the positive electrode relative to the negative electrode in real time in the charging process;
(2) When the voltage of the negative electrode relative to the reference electrode is 0.2V (vs Li/Li + ) At this time, the full cell voltage of the positive electrode versus the negative electrode was recorded and used as the pre-charge cut-off voltage of the pouch cell.
In this embodiment, the pre-charge cut-off voltage of the soft-package battery cell is measured to be 3.46V.
Example 2
The soft-pack battery cell prepared in preparation example 1 was pre-charge-formed as follows:
(1) Taking the soft package battery core prepared in the preparation example 1, and pre-charging with current of 0.05C until the voltage of the soft package battery is 3.46V, so as to obtain a pre-charged soft package battery core;
(2) And continuously charging the soft package battery core after the pre-charging with the current of 0.15C until the voltage of the soft package battery core reaches 4.3V of full-charge voltage, thereby obtaining the soft package battery core after the pre-charging and formation.
Example 3
The soft-pack battery cell prepared in preparation example 1 was pre-charge-formed as follows:
(1) Taking the soft package battery core prepared in the preparation example 1, and pre-charging with current of 0.05C until the voltage of the soft package battery is 3.46V, so as to obtain a pre-charged soft package battery core;
(2) And continuously charging the soft package battery core after the pre-charging with the current of 0.3C until the voltage of the soft package battery core reaches 4.3V of full-charge voltage, thereby obtaining the soft package battery core after the pre-charging and formation.
Example 4
The soft-pack battery cell prepared in preparation example 1 was pre-charge-formed as follows:
(1) Taking the soft package battery core prepared in the preparation example 1, and pre-charging with current of 0.05C until the voltage of the soft package battery is 3.46V, so as to obtain a pre-charged soft package battery core;
(2) And continuously charging the soft package battery core after the pre-charging with the current of 0.05C until the voltage of the soft package battery core reaches 4.3V of full-charge voltage, thereby obtaining the soft package battery core after the pre-charging and formation.
Example 5
The soft-pack battery cell prepared in preparation example 1 was pre-charge-formed as follows:
(1) Taking the soft package battery core prepared in the preparation example 1, and pre-charging with current of 0.1C until the voltage of the soft package battery is 3.46V, so as to obtain a pre-charged soft package battery core;
(2) And continuously charging the soft package battery core after the pre-charging with the current of 0.15C until the voltage of the soft package battery core reaches 4.3V of full-charge voltage, thereby obtaining the soft package battery core after the pre-charging and formation.
Comparative example 1
The soft-pack battery cell prepared in preparation example 1 was pre-charge-formed as follows:
(1) Taking the soft-packaged battery cell prepared in the preparation example 1, and pre-charging with a current of 0.05C until the voltage of the soft-packaged battery cell is 3.27V (wherein 3.27V corresponds to the voltage at the end of gas production, and the voltage of the negative electrode is 0.41V) to obtain a pre-charged soft-packaged battery cell;
(2) And continuously charging the soft package battery core after the pre-charging with the current of 0.15C until the voltage of the soft package battery core reaches 4.3V of full-charge voltage, thereby obtaining the soft package battery core after the pre-charging and formation.
Comparative example 2
The soft-pack battery cell prepared in preparation example 1 was pre-charge-formed as follows:
(1) Taking the soft package battery core prepared in the preparation example 1, and pre-charging with current of 0.5C until the voltage of the soft package battery is 3.46V, so as to obtain a pre-charged soft package battery core;
(2) And continuously charging the soft package battery core after the pre-charging with the current of 0.15C until the voltage of the soft package battery core reaches 4.3V of full-charge voltage, thereby obtaining the soft package battery core after the pre-charging and formation.
Experimental example 1
The impedance of the soft pack battery after pre-charge-formation was tested as follows:
and testing the impedance value of the soft-package battery cell after the pre-charge and formation by using electrochemical operation, wherein the disturbance signal is 10mV, and the frequency is 100000-0.1 Hz. The soft pack batteries obtained in examples 2 to 5 and comparative examples 1 to 2 were respectively tested, and the test results are shown in table 1.
Table 1 impedance test results of each of the pre-charge-formed pouch batteries
| Soft package battery core | Impedance (milliohm) |
| Example 2 | 9.1 |
| Example 3 | 9.2 |
| Example 4 | 9.2 |
| Example 5 | 9.4 |
| Comparative example 1 | 12.3 |
| Comparative example 2 | 21.2 |
Experimental example 2
The capacity retention after 10, 20, 30, 40, 50 cycles of the pre-charge-formed pouch cell was tested as follows:
the battery was charged to 4.2V at 0.5C, left to stand for 5 minutes, then discharged to 2.8V at 0.5C, left to stand for 5 minutes; and (5) circulating according to the above steps. The soft pack batteries obtained in examples 2 to 5 and comparative examples 1 to 2 were respectively tested, and the test results are shown in table 2.
TABLE 2 results of cycle performance test of soft pack batteries after each pre-charge-formation
As can be seen from the test results of example 2 and comparative examples 1 and 2, the pre-charge formation method of the present invention can effectively improve the cycle stability of the battery, because the method improves the stability of the negative electrode surface SEI film; as can be seen from the test results of example 2 and example 3, in the method of the present invention, after the small current is charged to the pre-charge cut-off voltage, the improvement of the current in the continuous charging stage has no significant effect on the cycle stability of the battery, that is, the stability of the SEI film on the surface of the negative electrode.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. A method of pre-charge formation of a battery, comprising the steps of:
pre-charging the battery with a first current until the voltage of the battery reaches a pre-charging cut-off voltage to obtain a pre-charged battery;
continuously charging the pre-charged battery with a second current until the voltage of the battery reaches a full-charge voltage;
the current value of the first current is not higher than 0.2C, and the pre-charge cut-off voltage is the full battery voltage corresponding to the condition that the negative electrode voltage of the battery is not higher than 0.2V.
2. The pre-charge formation method according to claim 1, wherein a current value of the second current is larger than a current value of the first current.
3. The precharge method according to claim 2, wherein a current value of the second current is not lower than 0.1C.
4. A precharge formation method according to any one of claims 1 to 3, wherein the process of determining the precharge cutoff voltage includes:
charging a three-electrode cell with a third current, wherein the three-electrode cell comprises a positive electrode, a negative electrode and a reference electrode;
and when the voltage of the negative electrode relative to the reference electrode is not higher than 0.2V, determining the full-cell voltage of the positive electrode relative to the negative electrode as the pre-charge cut-off voltage.
5. The method according to claim 4, wherein the third current has a current value of 0.01 to 5 ℃.
6. The method of pre-charge formation according to claim 4, wherein the battery is composed of the same type of cells as the three-electrode cells.
7. The method of pre-charge formation according to claim 4, wherein in the three-electrode cell, the positive electrode includes at least one of a lithium nickel cobalt manganese oxide positive electrode, a lithium iron phosphate positive electrode, a lithium cobalt oxide positive electrode, a lithium manganese oxide positive electrode, and a lithium nickel oxide positive electrode;
and/or the negative electrode comprises at least one of a graphite negative electrode, a silicon oxide negative electrode, a silicon carbon negative electrode and a silicon oxygen carbon negative electrode;
and/or the reference electrode comprises a lithium-plated copper wire electrode and/or a lithium electrode.
8. The pre-charge formation method according to any one of claims 1 to 7, wherein in the battery, the formation process and/or the reconstruction process of the negative electrode SEI film occur in a region of a negative electrode voltage of 0.2V or more.
9. A method of manufacturing a battery, characterized in that the method of manufacturing comprises the pre-charge formation method according to any one of claims 1 to 8.
10. A battery prepared by the preparation method of claim 9.
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