CN117458097A - Liquid injection method of battery - Google Patents
Liquid injection method of battery Download PDFInfo
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- CN117458097A CN117458097A CN202311191243.3A CN202311191243A CN117458097A CN 117458097 A CN117458097 A CN 117458097A CN 202311191243 A CN202311191243 A CN 202311191243A CN 117458097 A CN117458097 A CN 117458097A
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- 238000002347 injection Methods 0.000 title claims abstract description 144
- 239000007924 injection Substances 0.000 title claims abstract description 144
- 239000007788 liquid Substances 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 38
- 239000003792 electrolyte Substances 0.000 claims abstract description 110
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 27
- 238000010277 constant-current charging Methods 0.000 claims description 43
- 238000007600 charging Methods 0.000 claims description 23
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 6
- 238000005056 compaction Methods 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 230000000052 comparative effect Effects 0.000 description 25
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 18
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 12
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 11
- 229910001416 lithium ion Inorganic materials 0.000 description 11
- 230000008569 process Effects 0.000 description 11
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 8
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 8
- -1 lithium tetrafluoroborate Chemical group 0.000 description 7
- 239000000654 additive Substances 0.000 description 6
- 230000000996 additive effect Effects 0.000 description 6
- 229910013872 LiPF Inorganic materials 0.000 description 5
- 101150058243 Lipf gene Proteins 0.000 description 5
- 238000001764 infiltration Methods 0.000 description 5
- 230000008595 infiltration Effects 0.000 description 5
- 238000003475 lamination Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 4
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 229910052744 lithium Inorganic materials 0.000 description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- 239000007774 positive electrode material Substances 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 206010027146 Melanoderma Diseases 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000013538 functional additive Substances 0.000 description 2
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- 229910013075 LiBF Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 238000002847 impedance measurement Methods 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009736 wetting 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
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
- H01M50/609—Arrangements or processes for filling with liquid, e.g. electrolytes
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Filling, Topping-Up Batteries (AREA)
Abstract
The invention relates to the technical field of batteries, in particular to a liquid injection method of a battery. The battery comprises a shell, a positive plate, a negative plate, a diaphragm and electrolyte, wherein the liquid injection method comprises primary liquid injection and primary formation; the electrolyte injection amount of the primary injection is more than 82% and less than 96% by mass of the total electrolyte mass, and the length-to-height ratio and the aspect ratio of the electrolyte injection amount of the primary injection to the shell satisfy the following formulas:wherein x represents the length-to-height ratio of the shell, y represents the length-to-width ratio of the shell, and z represents the mass percentage of the electrolyte injection amount of one injection to the total electrolyte mass; the length-height ratio is more than 3.0 and less than 6.0; the aspect ratio is 10.0 or more and 20.0 or less. The method provided by the invention can effectively improve the wettability of the pole piece in the battery; meanwhile, the battery can be formed into a pole piece after one injection without black spots.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a liquid injection method of a battery.
Background
The lithium ion battery mainly comprises a positive electrode, a negative electrode, an electrolyte and the like, wherein the electrolyte does not provide capacity but is used for conducting Li between the positive electrode and the negative electrode + Therefore, the cycle life, the rate performance and other characteristics of the lithium ion battery have close relation with the electrolyte. The electrolyte can continuously generate oxidation and reduction reactions at the anode and the cathode in the working process of the lithium ion battery, so that the lithium ion battery is provided with too little liquid injectionMeanwhile, if the quantity of the electrolyte is too small, part of active substances cannot infiltrate, so that the capacity of the battery is not exerted, but too much liquid injection quantity also causes the problems of energy density reduction, cost increase and the like of the lithium ion battery.
The liquid injection process is a key process for manufacturing the lithium ion battery. In general, the battery is difficult to inject all electrolyte into the battery at one time, the injection is divided into two injections, the quantity of the primary injection quantity needs to be confirmed, the primary injection quantity is too much, the injection time can be increased, and even liquid injection is seriously caused, so that the injection efficiency and the productivity are affected; the once liquid injection amount is too small, so that the poor infiltration of the pole piece can be caused, the gas production in the formation process is too much, the internal resistance of the battery is increased, and the battery performance is affected, therefore, the proper liquid injection amount is particularly important for the lithium battery.
In the related art, a common lithium ion battery determines a primary liquid injection amount according to a liquid injection coefficient, specifically, determines a battery model capacity, then determines a liquid injection coefficient (2.5-4) of the battery, and then determines a total liquid injection amount of the battery according to a formula of the liquid injection coefficient = electrolyte density-theoretical liquid injection amount/design capacity = (electrolyte density- (positive electrode plate aperture + negative electrode plate aperture + diaphragm aperture))/design capacity, wherein the primary liquid injection amount of the common battery always accounts for 80% -90% of the total liquid injection amount;
for the battery with a special length-width ratio and/or a special length-height ratio, due to the specificity of the size structure, the transmission path of the electrolyte after liquid injection is overlong or the transmission surface is too wide, and once the electrolyte is injected for one time, the electrolyte is often directly caused to have insufficient wettability, so that black spots appear after the battery is formed.
Disclosure of Invention
The invention aims to provide a method for solving the problem that black spots appear in the formation of a battery after one-time liquid injection.
In the prior art, for a battery with a special length-width ratio and/or a special length-height ratio, due to the specificity of the size structure, the transmission path of electrolyte after liquid injection is overlong or the transmission surface is too wide, and once the electrolyte is injected for one time, the electrolyte is often directly caused to have insufficient wettability, so that black spots appear after the battery is formed; for example, in order to replace the volume release in the longitudinal space in the vehicle, the tab of the battery is designed in the length/width direction of the battery, but not in the height direction of the battery, so that the space utilization rate is improved;
based on the above, when the battery with the special aspect ratio and/or the special length-height ratio continues to be used for filling the liquid from the liquid filling port according to the liquid filling amount and the method of the common lithium ion battery described in the background art, the transmission path of the electrolyte is forced to be elongated or widened due to the overlong transmission path or the excessively wide transmission surface of the battery, and once the shortage of the primary liquid filling occurs, the shortage of wettability of the electrolyte is often directly caused, and further, black spots appear after the battery is formed. The black spot is mainly caused by concentration polarization (phenomenon that the electrode potential deviates from the balance potential due to the difference of ion concentration in the insufficient area and the normal area) when the electrolyte is insufficient in wettability, and further the black spot phenomenon is caused by the increase of the temperature in the insufficient area.
If the mode of continuously referring to the injection coefficient of the common lithium ion battery and further pushing out the primary injection amount ratio on the type of battery, the primary injection amount suitable for the battery cannot be obtained, so that the related parameters such as electrolyte density, positive electrode plate aperture, negative electrode plate aperture, diaphragm aperture and the like are not applicable any more;
in this regard, the inventors creatively proposed that the wettability of this type of battery can be effectively improved by obtaining the electrolyte injection amount of one injection of the electrolyte for the long-to-high ratio and the aspect ratio of this type of battery, and that the wettability of the battery is also affected when the ratio of the long-to-high ratio and the aspect ratio is too large.
The invention provides a liquid injection method of a battery, the battery comprises a positive plate, a negative plate, a diaphragm and electrolyte, and the liquid injection method comprises the following steps:
the liquid injection method comprises one-time liquid injection and one-time formation;
the electrolyte injection amount of the primary injection is more than 82% and less than 96% by mass of the total electrolyte mass, and the length-to-height ratio and the aspect ratio of the electrolyte injection amount of the primary injection to the shell satisfy the following formulas:
wherein x represents the length-to-height ratio of the shell, y represents the length-to-width ratio of the shell, and z represents the mass percentage of the electrolyte injection amount of one injection to the total electrolyte mass; the aspect ratio is 3.0 to 6.0, and the aspect ratio is 10.0 to 20.0.
It is to be noted that the case in this embodiment is formed in a rectangular shape having long sides and short sides as viewed from the lamination direction of the plurality of electrodes, the long sides referring to the length of the case, the short sides referring to the width of the case, and the thickness in the direction perpendicular to the rectangular face referring to the height of the case.
The inventor experiments found that, especially in this type of battery, too high compaction density of the positive electrode sheet can lead to too low porosity of the electrode sheet, which hinders transmission and diffusion of lithium ions in the electrolyte channel, too large compaction, increased rebound, increased side reactions at the interface, resulting in increased chemical resistance, reduced distance between contacts of active materials, and reduced physical resistance, so that in practice electrochemical impedance changes, whereby:
in a more preferred embodiment, the positive plate has a compacted density of 2.25g/cm 3 Above and 2.65g/cm 3 Hereinafter, by further limiting the compacted density of the positive electrode sheet, wettability of the battery can be improved.
It should be noted that, the impregnation process of the electrolyte can be generally divided into the following steps: 1. firstly, electrolyte starts to enter from a liquid injection port on one side of the shell; 2. the electrolyte diffuses along the electrode and the diaphragm under the action of capillary pressure; 3. since the electrolyte diffuses faster along the separator, the electrolyte diffuses more rapidly from the separator into the electrode. Therefore, the wettability among the contact angle control electrolyte, the electrode plate and the diaphragm is an important parameter of the electrolyte, and the poor wettability or uneven wettability can be caused by the improper contact angle, so that black spots appear in formation;
in a more preferred embodiment, the contact angle between the electrolyte and the separator is greater than the contact angle between the electrolyte and the positive electrode sheet. In a more preferred embodiment, the contact angle between the electrolyte and the separator is more than 10 ° and less than 85 °, and the contact angle between the electrolyte and the separator is further limited, so that wettability of the battery can be further improved, and preferably, the contact angle between the electrolyte and the separator is more than 12 ° and less than 36 °, and more preferably, the contact angle between the electrolyte and the separator is 21.1 °. In a more preferred embodiment, the contact angle between the electrolyte and the positive electrode sheet is more than 10 ° and less than 80 °, preferably, the contact angle between the electrolyte and the positive electrode sheet is more than 10 ° and less than 30 °, further limiting the contact angle between the electrolyte and the positive electrode sheet, and further improving the wettability of the battery, and more preferably, the contact angle between the electrolyte and the positive electrode sheet is 18.4 °.
In a more preferred embodiment, the direction of the injection is vertical, and the flow rate of the electrolyte at the time of injection is more than 2.3L/min and less than 10.1L/min, preferably, the flow rate of the electrolyte at the time of injection is more than 3.6L/min and less than 7.2L/min, and more preferably, the flow rate of the electrolyte at the time of injection is 5.63L/min. When the electrolyte is injected, the battery cell is placed perpendicular to the ground in the length direction, the electrolyte injection hole is upward, and electrolyte can be gradually infiltrated from top to bottom when the electrolyte is injected vertically, so that poor wettability of one side of the battery cell in the length direction is avoided.
It should be noted that the battery cell is placed perpendicular to the ground in the length direction during liquid injection, and the liquid injection hole faces upwards. The vertical direction here is the longitudinal direction.
In a more preferred embodiment, the pressure in the electrolyte chamber is above 0.1Mpa and below 5Mpa, preferably above 0.15Mpa and below 1Mpa, more preferably below 0.25Mpa.
In a more preferred embodiment, the electrolyte has a water content of < 100ppm, preferably the electrolyte containsThe water content was 10ppm; the hydrofluoric acid content of the electrolyte is less than 100ppm, and preferably, the hydrofluoric acid content of the electrolyte is 20ppm; the density of the electrolyte is 0.8g/cm 3 Above and 1.6g/cm 3 Hereinafter, the density of the electrolyte is preferably 1.2g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The electrolyte has a conductivity of 6mS/cm or more and 15mS/cm or less at 25 ℃.
In a more preferred embodiment, the electrolyte comprises, in mass percent: 70% -87% of solvent, 10% -20% of lithium source and 3% -10% of functional additive.
The solvent is at least one selected from Propylene Carbonate (PC), ethylene Carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC); preferably, a solvent with high and low viscosity is used, for example: the combination is Ethylene Carbonate (EC) +diethyl carbonate (DEC), ethylene Carbonate (EC) +dimethyl carbonate (DMC) +methylethyl carbonate (EMC), ethylene Carbonate (EC) +dimethyl carbonate (DMC) +diethyl carbonate (DEC), etc., preferably Ethylene Carbonate (EC) +dimethyl carbonate (DMC) +diethyl carbonate (DEC) is used.
The lithium source is selected from lithium tetrafluoroborate (LiBF) 4 ) Lithium hexafluorophosphate (LiPF) 6 ) At least one of the novel lithium salts lithium bis (fluorosulfonyl) imide (LiFSI); preferably, the lithium source is lithium hexafluorophosphate (LiPF 6 )。
The functional additive is at least one selected from film forming additive, high temperature additive, low temperature additive, overcharge protection additive, flame retardant additive and multiplying power additive; for example, vinylene Carbonate (VC) and fluoroethylene carbonate (FEC) are selected, and preferably Vinylene Carbonate (VC) is added.
Of course, the electrolyte may be a combination of other substances known in the art.
In a more preferred embodiment, the temperature of the primary formation is above 25 ℃ and below 55 ℃ and the vacuum level is above-150 kPa and below-20 kPa. More preferably, the primary formation temperature is above 40 ℃ and below 50 ℃, especially 45 ℃; more preferably, the vacuum is above-75 kPa and below-60 kPa, especially-70 kPa.
Too low or too high a formation temperature may cause black spots on the interface formation when the wettability of the injected electrolyte is insufficient. In addition, the negative pressure is particularly adopted in the formation process of the invention to timely discharge the gas generated in the formation process, so as to avoid bad contact between the pole pieces, the diaphragm and the pole pieces caused by the generation of the gas, and further to generate black spots.
In a more preferred embodiment, the single-pass formation comprises the steps of:
standing for the first time; primary constant current charging; standing for the second time; secondary constant current charging; standing for three times;
the current of the secondary constant current charging is larger than that of the primary constant current charging, and the time of the secondary constant current charging is shorter than that of the primary constant current charging.
Experiments of the inventor find that a small-current pre-charging mode is beneficial to stable SEI film formation in the formation process, but long-time small-current charging can cause increase of resistance of the SEI film formed, so that rate discharge performance of the lithium ion battery is affected, and production efficiency is affected due to long process time; whereby:
in a more preferred embodiment, the charging current of the primary constant current charging is above 0.01C and below 0.1C, and preferably, the charging current of the primary constant current charging is 0.025C.
In a more preferred embodiment, the charging current of the secondary constant current charging is above 0.05C and below 0.5C, and preferably, the charging current of the secondary constant current charging is 0.3C.
In a more preferred embodiment, the charging current of the primary constant current charging is above 0.01C and below 0.1C and/or the charging current of the secondary constant current charging is above 0.05C and below 0.5C.
In a more preferred embodiment, the time of the primary constant current charging is 50-360min, and preferably, the time of the primary constant current charging is 150min; the time of the secondary constant current charging is 30-360min, preferably 89min.
In a more preferred embodiment, the time of the one standing is 5-60min, preferably, the time of the one standing is 10min; the secondary standing time is 10-120min, preferably 45min; the three times of standing are 10-120min, preferably 10min.
It is worth noting that the invention particularly adopts a mode of two-stage interval constant current charging, the current of the secondary constant current charging is 8-16 times of the current of the primary constant current charging, based on the constant current charging mode, compared with the conventional one-stage constant current charging, the SEI film is firstly formed step by step in the charging process of smaller current, and the SEI film layer formed can be stabilized step by step in the time of secondary standing, further in the secondary constant current charging process, because the charging current used by the secondary constant current charging is higher, the side reaction can be completely reacted, and more importantly, because the secondary constant current charging current is higher, the SEI film after secondary standing further forms a more compact SEI film.
In summary, the present application includes at least one of the following beneficial technical effects:
the method provided by the invention can effectively improve the wettability of the pole piece in the battery;
the method provided by the invention can lead the battery to be formed into the pole piece after one injection without black spots.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
For a clearer description of embodiments of the invention or of the solutions of the prior art, the drawings that are needed in the description of the embodiments or of the prior art will be briefly described, it being obvious that the drawings in the description below are some embodiments of the invention, and that other drawings can be obtained from them without inventive effort for a person skilled in the art; the positional relationships described in the drawings in the following description are based on the orientation of the elements shown in the drawings unless otherwise specified.
Fig. 1 is a schematic view of a battery structure according to an embodiment of the present invention;
fig. 2 is a graph of impedance measurements for different positive plate densities.
Reference numerals:
10. a housing; 11. and a liquid injection port.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The technical scheme of the invention is further illustrated and described through specific examples. The scope of the invention is not limited in this respect.
Comparative example 1
The aspect ratio of the battery is 6, the length-height ratio is 3.6, and the primary liquid injection amount accounts for 82.5 percent. Specifically, a battery having a length of 340.6mm, a width of 56.7mm, and a height of 94.6mm was fabricated. Graphite is used as a negative electrode material to manufacture a negative electrode plate, lithium iron phosphate is used as a positive electrode material to manufacture a positive electrode plate, a PE base film is adopted as a diaphragm, and the positive electrode is compacted by 2.47g/cm 3 . And (5) adopting a positive electrode-diaphragm-negative electrode lamination to form a core package, and assembling the battery. Then injecting liquid once, wherein the electrolyte adopts 32 percent of Ethylene Carbonate (EC) +48 percent of dimethyl carbonate (DMC) +15 percent of lithium hexafluorophosphate (LiPF) 6 ) +5% Vinylene Carbonate (VC). The primary injection amount was 445.5g (total injection amount 540 g), the flow rate at the time of injection was 5.63L/min, the contact angle of the electrolyte with the separator was 21.1℃and the contact angle of the electrolyte with the positive electrode sheet was 18.4 ℃. Standing for 10min at one time, then standing at 45 ℃,the formation is carried out under 75KPa, the charging current of primary constant current charging is 4.125A, secondary standing is carried out for 45min, the charging current of secondary constant current charging is 49.5A, and the time of tertiary standing is 10min. And after the end, welding the sealing nails to fully charge and disassemble the battery, and analyzing the electrode plate interface.
Comparative example 2
The aspect ratio of the battery is 9, the length-height ratio is 3.6, and the primary liquid injection amount accounts for 84 percent. Specifically, a battery having a length of 340.6mm, a width of 37.8mm, and a height of 94.6mm was fabricated. Graphite is used as a negative electrode material to manufacture a negative electrode plate, lithium iron phosphate is used as a positive electrode material to manufacture a positive electrode plate, a PE base film is adopted as a diaphragm, and the positive electrode is compacted by 2.47g/cm 3 . And (5) adopting a positive electrode-diaphragm-negative electrode lamination to form a core package, and assembling the battery. Then injecting liquid once, wherein the electrolyte adopts 32 percent of Ethylene Carbonate (EC) +48 percent of dimethyl carbonate (DMC) +15 percent of lithium hexafluorophosphate (LiPF) 6 ) +5% Vinylene Carbonate (VC). The primary injection amount was 453.6g (540 g total injection amount), the flow rate at the time of injection was 5.63L/min, the contact angle of the electrolyte with the separator was 21.1℃and the contact angle of the electrolyte with the positive electrode sheet was 18.4 ℃. Standing for 10min at 45 ℃ and 75KPa, performing formation, wherein the charging current of primary constant current charging is 4.125A, standing for 45min at the second time, the charging current of secondary constant current charging is 49.5A, and standing for 10min at the third time. And after the end, welding the sealing nails to fully charge and disassemble the battery, and analyzing the electrode plate interface.
Example 1
The aspect ratio of the battery is 12, the length-height ratio is 3.6, and the primary liquid injection amount accounts for 85.5 percent. Specifically, a battery having a length of 340.6mm, a width of 28.4mm, and a height of 94.6mm was fabricated. Graphite is used as a negative electrode material to manufacture a negative electrode plate, lithium iron phosphate is used as a positive electrode material to manufacture a positive electrode plate, a PE base film is adopted as a diaphragm, and the positive electrode is compacted by 2.47g/cm 3 . And (5) adopting a positive electrode-diaphragm-negative electrode lamination to form a core package, and assembling the battery. Then injecting liquid once, wherein the electrolyte adopts 32 percent of Ethylene Carbonate (EC) +48 percent of dimethyl carbonate (DMC) +15 percent of lithium hexafluorophosphate (LiPF) 6 ) +5% Vinylene Carbonate (VC). The primary injection amount is 461.7g (total injection amount is 540 g), the flow rate during injection is 5.63L/min, the contact angle between the electrolyte and the diaphragm is 21.1 degrees, and the electrolyte and the positive plateThe contact angle was 18.4 °. Standing for 10min at 45 ℃ and 75KPa, performing formation, wherein the charging current of primary constant current charging is 4.125A, standing for 45min at the second time, the charging current of secondary constant current charging is 49.5A, and standing for 10min at the third time. And after the end, welding the sealing nails to fully charge and disassemble the battery, and analyzing the electrode plate interface.
Example 2
The aspect ratio of the battery is 15, the length-height ratio is 3.6, and the primary liquid injection amount accounts for 87 percent. Specifically, a battery having a length of 340.6mm, a width of 22.7mm, and a height of 94.6mm was fabricated. Graphite is used as a negative electrode material to manufacture a negative electrode plate, lithium iron phosphate is used as a positive electrode material to manufacture a positive electrode plate, a PE base film is adopted as a diaphragm, and the positive electrode is compacted by 2.47g/cm 3 . And (5) adopting a positive electrode-diaphragm-negative electrode lamination to form a core package, and assembling the battery. Then injecting liquid once, wherein the electrolyte adopts 32 percent of Ethylene Carbonate (EC) +48 percent of dimethyl carbonate (DMC) +15 percent of lithium hexafluorophosphate (LiPF) 6 ) +5% Vinylene Carbonate (VC). The primary injection amount was 469.8g (total injection amount 540 g), the flow rate at the time of injection was 5.63L/min, the contact angle of the electrolyte with the separator was 21.1℃and the contact angle of the electrolyte with the positive electrode sheet was 18.4 ℃. Standing for 10min at 45 ℃ and 75KPa, performing formation, wherein the charging current of primary constant current charging is 4.125A, standing for 45min at the second time, the charging current of secondary constant current charging is 49.5A, and standing for 10min at the third time. And after the end, welding the sealing nails to fully charge and disassemble the battery, and analyzing the electrode plate interface.
Example 3
The difference is that: the aspect ratio of the battery is 18, the length-height ratio is 3.6, and the primary injection amount accounts for 88.5 percent. A battery having a length of 340.6mm, a width of 18.6mm and a height of 94.6mm was fabricated. The single injection amount was 469.8g (total injection amount 540 g), and the other portions were the same as in example 1.
Comparative example 3
The difference is that: the aspect ratio of the battery is 21, the length-height ratio is 3.6, and the primary liquid injection amount accounts for 90 percent. A battery having a length of 340.6mm, a width of 16.2mm and a height of 94.6mm was fabricated. The primary injection amount was 486g (total injection amount 540 g), and the other was the same as in example 1.
Comparative example 4
The difference is that: the aspect ratio of the battery is 6, the length-height ratio is 4.5, and the primary liquid injection amount accounts for 85.5 percent. A battery having a length of 340.6mm, a width of 56.7mm and a height of 75.7mm was fabricated. The amount of the primary injection was 461.7g (total injection amount 540 g), and the other matters were the same as in example 1.
Comparative example 5
The difference is that: the aspect ratio of the battery is 9, the length-height ratio is 4.5, and the primary liquid injection amount accounts for 87 percent. A battery having a length of 340.6mm, a width of 37.8mm and a height of 75.7mm was fabricated. The single injection amount was 469.8g (total injection amount 540 g), and the other portions were the same as in example 1.
Example 4
The difference is that: the aspect ratio of the battery is 12, the length-height ratio is 4.5, and the primary liquid injection amount accounts for 88.5 percent. A battery having a length of 340.6mm, a width of 28.4mm and a height of 75.7mm was fabricated. The amount of the primary liquid injection was 477.9g (total liquid injection amount 540 g), and the other portions were the same as in example 1.
Example 5
The difference is that: the aspect ratio of the battery is 15, the length-height ratio is 4.5, and the primary liquid injection amount accounts for 90 percent. A battery having a length of 340.6mm, a width of 22.7mm and a height of 75.7mm was fabricated. The primary injection amount was 486g (total injection amount 540 g), and the other was the same as in example 1.
Example 6
The difference is that: the aspect ratio of the battery is 18, the length-height ratio is 4.5, and the primary injection amount accounts for 91.5%. A battery having a length of 340.6mm, a width of 18.9mm and a height of 75.7mm was fabricated. The amount of the primary injection was 494.1g (total injection amount 540 g), and the other matters were the same as in example 1.
Comparative example 6
The difference is that: the aspect ratio of the battery is 21, the length-height ratio is 4.5, and the primary liquid injection amount accounts for 93 percent. A battery having a length of 340.6mm, a width of 16.2mm and a height of 75.7mm was fabricated. The amount of the primary liquid injection was 502.2g (total liquid injection amount 540 g), and the other portions were the same as in example 1.
Comparative example 7
The difference is that: the aspect ratio of the battery is 6, the length-height ratio is 5.4, and the primary liquid injection amount accounts for 88.5 percent. A battery having a length of 340.6mm, a width of 56.7mm and a height of 63.1mm was fabricated. The amount of the primary liquid injection was 477.9g (total liquid injection amount 540 g), and the other portions were the same as in example 1.
Comparative example 8
The difference is that: the aspect ratio of the battery is 9, the length-height ratio is 5.4, and the primary liquid injection amount accounts for 90 percent. A battery having a length of 340.6mm, a width of 37.8mm and a height of 63.1mm was fabricated. The primary injection amount was 486g (total injection amount 540 g), and the other was the same as in example 1.
Example 7
The difference is that: the aspect ratio of the battery is 12, the length-height ratio is 5.4, and the primary injection amount accounts for 91.5%. A battery having a length of 340.6mm, a width of 28.4mm and a height of 63.1mm was fabricated. The amount of the primary injection was 494.1g (total injection amount 540 g), and the other matters were the same as in example 1.
Example 8
The difference is that: the aspect ratio of the battery is 15, the length-height ratio is 5.4, and the primary liquid injection amount accounts for 93 percent. A battery having a length of 340.6mm, a width of 22.7mm and a height of 63.1mm was fabricated. The amount of the primary liquid injection was 502.2g (total liquid injection amount 540 g), and the other portions were the same as in example 1.
Example 9
The difference is that: the aspect ratio of the battery is 18, the length-height ratio is 5.4, and the primary injection amount accounts for 94.5%. A battery having a length of 340.6mm, a width of 18.9mm and a height of 63.1mm was fabricated. The amount of the primary liquid injection was 510.3g (total liquid injection amount 540 g), and the other steps were the same as in example 1.
Comparative example 9
The difference is that: the aspect ratio of the battery is 21, the length-height ratio is 5.4, and the primary liquid injection amount accounts for 96%. A battery having a length of 340.6mm, a width of 16.2mm and a height of 63.1mm was fabricated. The primary injection amount was 518.4g (total injection amount 540 g), and the other portions were the same as in example 1.
Comparative example 10
The difference is that: the aspect ratio of the battery is 12, the length-height ratio is 2.7, and the primary injection amount accounts for 82.5%. A battery with a length of 340.6mm, a width of 28.4mm and a height of 126.1mm was fabricated. The amount of the liquid to be injected at one time was 445.5g (total amount of liquid to be injected was 540 g), and the other portions were the same as in example 1.
Comparative example 11
The difference is that: the aspect ratio of the battery is 18, the length-height ratio is 2.7, and the primary liquid injection amount accounts for 85.5 percent. A battery having a length of 340.6mm, a width of 18.9mm and a height of 126.1mm was fabricated. The amount of the primary injection was 461.7g (total injection amount 540 g), and the other matters were the same as in example 1.
Comparative example 12
The difference is that: the aspect ratio of the battery is 12, the length-height ratio is 6.3, and the primary injection amount accounts for 94.5 percent. A battery having a length of 340.6mm, a width of 28.4mm and a height of 54.1mm was fabricated. The amount of the primary injection was 510.3g (total injection amount 540 g), and the other portions were the same as in example 1.
Comparative example 13
The difference is that: the aspect ratio of the battery is 18, the length-height ratio is 6.3, and the primary injection amount accounts for 97.5 percent. A battery having a length of 340.6mm, a width of 18.9mm and a height of 54.1mm was fabricated. The amount of the primary injection was 526.5g (total injection amount 540 g), and the other matters were the same as in example 1.
Comparative example 14
The difference is that: in the primary formation, constant current charging was performed only once, the charging current was 0.1C, the standing time was 55min, and the rest was the same as in example 1.
Comparative example 15
The difference is that: in the primary formation, constant current charging was performed only once, the charging current was 0.1C, the standing time was 8h, and the rest was the same as in example 1.
Comparative example 16
The difference is that: the rest temperature at the time of one rest was 45℃and the rest was the same as in example 1.
Comparative example 17
The difference is that: the compacted density of the positive plate is 2.7g/cm 3 The remainder was identical to example 1.
Comparative example 18
The difference is that: the compacted density of the positive plate is 2.2g/cm 3 The remainder was identical to example 1.
The battery is manufactured by a shell 10, a positive plate, a negative plate, a diaphragm and electrolyte. The positive and negative plates are cut according to the size and then are stacked together with the diaphragm, and are put into the shell, and electrolyte is injected through the liquid injection port 11 for formation.
And disassembling the battery core after formation, confirming the electrolyte infiltration condition of the electrode plate interface, and confirming whether the electrode plate interface has black spots or not, wherein the specific cross experiment results are shown in the table below.
Table 1 test results for examples, comparative examples
Remarks: more "+" represents worse wetting, more black spots are formed, and "0" represents good.
As is clear from comparative examples 1 to 9, since the injection of the electrolyte is performed from the injection port on one side, the aspect ratio is too high, but as shown in fig. 1, the electrolyte infiltration channel of the battery is too deep and narrow, and it is difficult to sufficiently infiltrate the battery cell to the end, while if the aspect ratio is too low, the infiltration channel is too wide, so that the electrolyte flowing from the injection port is difficult to sufficiently spread out to infiltrate, resulting in poor wettability and formation of black spots;
as is clear from comparative examples 10 to 13, although the aspect ratios were 12 and 18, respectively, it was difficult for the electrolyte infiltration channels formed by the cross sections thereof to sufficiently infiltrate the cells to form black spots due to the excessively high or excessively low aspect ratio;
as can be seen from comparative examples 14 to 15, the stationary battery cell was once formed, and compared with the two-stage constant current charging method used in the examples, the stationary current charging method was long-time charged with a stationary current, which resulted in insufficient reaction at the interface of the battery pole piece due to insufficient rest time, which affected the formation of the SEI film, but the compactness of the SEI film was relatively low after sufficient rest, which resulted in affecting the overall performance of the battery;
according to comparative example 16, although the electrolyte is immersed at a high temperature during one-time standing, the time required by the electrolyte is longer, and the electrolyte can be injected efficiently and rapidly, the electrolyte can be injected at room temperature during standing, and high-temperature negative pressure is synchronously applied during constant-current charging, so that the production efficiency and the electrolyte wettability are effectively improved, and meanwhile, the generation of black spots is reduced;
the invention also performs electrolyte wettability analysis for positive electrode compacted density, as in comparative example 17: the compacted density of the positive plate is 2.7g/cm 3 (high compacted density), comparative example 18: the compacted density of the positive plate is 2.2g/cm 3 The EIS test and wettability and black spot observation of the (low compaction density) cell can be seen with reference to FIG. 2, the high compaction results in high interface impedance (charge exchange impedance), which means that the chemical resistance is higher, the physical resistance is lower, the pore of the pole piece is lower, the electrolyte is more difficult to infiltrate, the wettability is worse, and further, the interface is black spots are caused, and if the compaction density is too low, the electrolyte is easy to flow out and is difficult to infiltrate sufficiently.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. The utility model provides a annotate liquid method of battery, the battery includes shell, positive plate, negative plate, diaphragm and electrolyte, its characterized in that:
the liquid injection method comprises one-time liquid injection and one-time formation;
the electrolyte injection amount of the primary injection is more than 82% and less than 96% by mass of the total electrolyte mass, and the length-to-height ratio and the aspect ratio of the electrolyte injection amount of the primary injection to the shell satisfy the following formulas:
wherein x represents the length-to-height ratio of the shell, y represents the length-to-width ratio of the shell, and z represents the mass percentage of the electrolyte injection amount of one injection to the total electrolyte mass; the length-height ratio is more than 3.0 and less than 6.0; the aspect ratio is 10.0 or more and 20.0 or less.
2. The method of filling a battery according to claim 1, wherein: the compaction density of the positive plate is 2.25g/cm 3 Above and 2.65g/cm 3 The following is given.
3. The method of filling a battery according to claim 1, wherein: the contact angle of the electrolyte and the diaphragm is larger than the contact angle of the electrolyte and the positive pole piece.
4. A method of filling a battery according to claim 3, wherein: the contact angle of the electrolyte with the diaphragm is more than 10 DEG and less than 85 deg.
5. A method of filling a battery according to claim 3, wherein: the contact angle between the electrolyte and the positive pole piece is more than 10 degrees and less than 80 degrees.
6. The method of filling a battery according to claim 1, wherein: the injection direction of the primary injection is vertical injection, and the flow rate of the electrolyte is more than 2.3L/min and less than 10.1L/min during the injection.
7. The method of filling a battery according to claim 1, wherein: the water content of the electrolyte is less than 100ppm; the hydrofluoric acid content of the electrolyte is less than 100ppm; the density of the electrolyte is 0.8g/cm 3 Above and 1.6g/cm 3 The following are set forth; the electrolyte has a conductivity of 6mS/cm or more and 15mS/cm or less at 25 ℃.
8. The method of filling a battery according to claim 1, wherein the temperature of the primary formation is 25 ℃ or higher and 55 ℃ or lower, and the vacuum degree is-150 kPa or higher and-20 kPa or lower.
9. The method of filling a battery according to claim 1 or 8, wherein the primary formation comprises the steps of:
standing for the first time; primary constant current charging; standing for the second time; secondary constant current charging; standing for three times;
the current of the secondary constant current charging is larger than that of the primary constant current charging, and the time of the secondary constant current charging is shorter than that of the primary constant current charging.
10. The method of filling a battery according to claim 9, wherein: the charging current of the primary constant current charging is above 0.01C and below 0.1C and/or the charging current of the secondary constant current charging is above 0.05C and below 0.5C.
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| CN117995989A (en) * | 2024-04-07 | 2024-05-07 | 宁德时代新能源科技股份有限公司 | Battery and electricity utilization device |
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