WO2023174344A1 - 电池及用电设备 - Google Patents
电池及用电设备 Download PDFInfo
- Publication number
- WO2023174344A1 WO2023174344A1 PCT/CN2023/081698 CN2023081698W WO2023174344A1 WO 2023174344 A1 WO2023174344 A1 WO 2023174344A1 CN 2023081698 W CN2023081698 W CN 2023081698W WO 2023174344 A1 WO2023174344 A1 WO 2023174344A1
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- WIPO (PCT)
- Prior art keywords
- material layer
- negative electrode
- electrode material
- positive electrode
- pore diameter
- Prior art date
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- 239000011148 porous material Substances 0.000 claims abstract description 112
- 239000003792 electrolyte Substances 0.000 claims abstract description 82
- 239000007773 negative electrode material Substances 0.000 claims abstract description 55
- 239000007774 positive electrode material Substances 0.000 claims abstract description 50
- 238000012937 correction Methods 0.000 claims abstract description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 17
- 229910052744 lithium Inorganic materials 0.000 claims description 17
- 238000009826 distribution Methods 0.000 claims description 12
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 11
- 239000006258 conductive agent Substances 0.000 claims description 10
- 239000011230 binding agent Substances 0.000 claims description 9
- 239000004034 viscosity adjusting agent Substances 0.000 claims description 8
- 239000002033 PVDF binder Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 7
- 229910003002 lithium salt Inorganic materials 0.000 claims description 6
- 159000000002 lithium salts Chemical class 0.000 claims description 6
- 239000003960 organic solvent Substances 0.000 claims description 6
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 5
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 5
- 239000004642 Polyimide Substances 0.000 claims description 5
- 229920001721 polyimide Polymers 0.000 claims description 5
- 229920002125 Sokalan® Polymers 0.000 claims description 4
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 4
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 3
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 3
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 3
- XLDXZSVHMLAQMY-UHFFFAOYSA-N lithium;dioxalooxyborinate Chemical compound [Li+].OC(=O)C(=O)OB([O-])OC(=O)C(O)=O XLDXZSVHMLAQMY-UHFFFAOYSA-N 0.000 claims description 3
- 239000004584 polyacrylic acid Substances 0.000 claims description 3
- XKLXIRVJABJBLQ-UHFFFAOYSA-N lithium;2-(trifluoromethyl)-1h-imidazole-4,5-dicarbonitrile Chemical compound [Li].FC(F)(F)C1=NC(C#N)=C(C#N)N1 XKLXIRVJABJBLQ-UHFFFAOYSA-N 0.000 claims description 2
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 claims description 2
- 239000000853 adhesive Substances 0.000 claims 1
- 230000001070 adhesive effect Effects 0.000 claims 1
- 230000014759 maintenance of location Effects 0.000 abstract description 22
- 239000007788 liquid Substances 0.000 abstract description 3
- 230000001351 cycling effect Effects 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 10
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 239000002002 slurry Substances 0.000 description 6
- 229910052774 Proactinium Inorganic materials 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 238000011056 performance test Methods 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 239000011149 active material Substances 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 4
- 229910052753 mercury Inorganic materials 0.000 description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 3
- 239000002041 carbon nanotube Substances 0.000 description 3
- 229910021393 carbon nanotube Inorganic materials 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000005056 compaction Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920002239 polyacrylonitrile Polymers 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 238000002459 porosimetry Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 239000003981 vehicle Substances 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 1
- RBKMZOVCGJIRNQ-UHFFFAOYSA-N B([O-])(F)F.C(C(=O)O)(=O)O.[Li+] Chemical compound B([O-])(F)F.C(C(=O)O)(=O)O.[Li+] RBKMZOVCGJIRNQ-UHFFFAOYSA-N 0.000 description 1
- GGOVLNOXFVYTPN-UHFFFAOYSA-M C(C(=O)O)(=O)[O-].B(O)(F)F.[Li+] Chemical compound C(C(=O)O)(=O)[O-].B(O)(F)F.[Li+] GGOVLNOXFVYTPN-UHFFFAOYSA-M 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910002991 LiNi0.5Co0.2Mn0.3O2 Inorganic materials 0.000 description 1
- 229910011328 LiNi0.6Co0.2Mn0.2O2 Inorganic materials 0.000 description 1
- 229910015872 LiNi0.8Co0.1Mn0.1O2 Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- YWJVFBOUPMWANA-UHFFFAOYSA-H [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O Chemical compound [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O YWJVFBOUPMWANA-UHFFFAOYSA-H 0.000 description 1
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 239000006182 cathode active material Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000006232 furnace black Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 150000003949 imides Chemical class 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 239000003273 ketjen black Substances 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- BDKWOJYFHXPPPT-UHFFFAOYSA-N lithium dioxido(dioxo)manganese nickel(2+) Chemical compound [Mn](=O)(=O)([O-])[O-].[Ni+2].[Li+] BDKWOJYFHXPPPT-UHFFFAOYSA-N 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- SBWRUMICILYTAT-UHFFFAOYSA-K lithium;cobalt(2+);phosphate Chemical compound [Li+].[Co+2].[O-]P([O-])([O-])=O SBWRUMICILYTAT-UHFFFAOYSA-K 0.000 description 1
- DVATZODUVBMYHN-UHFFFAOYSA-K lithium;iron(2+);manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[Fe+2].[O-]P([O-])([O-])=O DVATZODUVBMYHN-UHFFFAOYSA-K 0.000 description 1
- ILXAVRFGLBYNEJ-UHFFFAOYSA-K lithium;manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[O-]P([O-])([O-])=O ILXAVRFGLBYNEJ-UHFFFAOYSA-K 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 235000010413 sodium alginate Nutrition 0.000 description 1
- 239000000661 sodium alginate Substances 0.000 description 1
- 229940005550 sodium alginate Drugs 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
- 239000007785 strong electrolyte Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000010998 test method 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
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
Definitions
- This application relates to the technical field of lithium batteries, and specifically to a battery and electrical equipment.
- both the positive and negative electrodes will change in volume to varying degrees. This volume change will cause the electrolyte to be extruded from between the electrodes of the battery core and the electrolyte to flow back.
- the phenomenon of delayed electrolyte return often occurs, especially for larger batteries such as wound batteries and laminated batteries.
- the phenomenon of delayed electrolyte return is more serious. Failure to reflow the electrolyte in time will cause some of the pole pieces in the battery core to be unable to contact the electrolyte, causing local lithium precipitation on the electrode pole pieces during the discharge process, and even creating safety hazards.
- the industry often solves the above problems by adjusting the composition of the electrolyte to increase the force between the electrolyte and the electrode pieces.
- the suitability between the electrolyte and the type of electrode pieces is required to be high, and this method is not universal and Universality.
- this application can ensure that the positive and negative electrodes meet certain requirements by adjusting the pore diameters and their respective pore size distributions of the positive and negative electrodes, and controlling the viscosity of the positive and negative electrodes and the electrolyte.
- the tablets have strong electrolyte retention capacity and are not prone to lithium precipitation during charging, resulting in the battery having good cycle stability, high capacity retention rate, and long battery cycle life.
- a first aspect of this application provides a battery.
- the battery includes a positive electrode piece, a negative electrode piece, an electrolyte and a separator located between the positive electrode piece and the negative electrode piece.
- the positive electrode piece includes a positive electrode current collector and a positive electrode material disposed on the positive electrode current collector.
- the negative electrode piece includes a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector, the positive electrode piece, the negative electrode piece and the electrolyte satisfy the following relationship:
- Ce represents the liquid-holding ability of the positive electrode piece and the negative electrode piece to the electrolyte, and the value range of Ce is 1.0g/Ah-5.0g/Ah; A is the correction factor; a is the electrolyte The viscosity at room temperature, in mPa ⁇ s; R is the capacity of the battery, in Ah; Bi is the capillary index of the pore diameter of the positive electrode material layer and B ii is the capillary index of the pore diameter of the negative electrode material layer The units of index, B i and B ii are m; m represents the maximum pore diameter in the pore diameter interval of the cathode material layer, i is the average pore diameter in different pore diameter intervals of the cathode material layer, and Pc i is the cathode material layer, the ratio of the pore volume when the pore diameter is i to the volume of the cathode material layer; n represents the maximum pore diameter within the aperture interval of the anode material layer,
- R is in the range of 0.1Ah-300Ah, and A is in the range of 0.01s-100s.
- R is in the range of 10Ah-200Ah.
- R is in the range of 10Ah-100Ah.
- the distribution range of the pore diameter of the positive electrode material layer is 20 nm-20000 nm
- the distribution range of the pore diameter of the negative electrode material layer is 20 nm-20000 nm.
- the values of i are 20000nm, 18000nm, 15000nm, 12000nm, 10000nm, 7500nm, 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm, 500nm, 320nm, 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm and 20nm; the value of ii is 20000nm, 18000n m, 15000nm, 12000nm, 10000nm, 7500nm , 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm, 500nm, 320nm, 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm and 20nm.
- the porosity of the positive electrode material layer is in the range of 10%-50%, and the porosity of the negative electrode material layer is in the range of 10%-70%.
- the minimum value of i and the minimum value of ii are both 50, and the values of m and n are both 20000 nm.
- a is in the range of 0.5mPa ⁇ s-50mPa ⁇ s.
- a is in the range of 0.5mPa ⁇ s-5mPa ⁇ s.
- the electrolyte includes an organic solvent and a lithium salt, wherein the lithium salt includes lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxaloborate, lithium oxalate difluoroborate, lithium bisfluorosulfonyl imide, and bistrifluoride.
- the lithium salt includes lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxaloborate, lithium oxalate difluoroborate, lithium bisfluorosulfonyl imide, and bistrifluoride.
- the organic solvent includes ethylene carbonate, diethyl carbonate, At least one of dimethyl carbonate and methyl ethyl carbonate.
- the electrolyte includes a viscosity modifier, and the viscosity modifier includes at least one of polyimide, polyvinylidene fluoride, and polyacrylic acid.
- the positive electrode material layer includes a positive electrode active material layer, a conductive agent, and a binder
- the negative electrode material layer includes a negative electrode active material, a conductive agent, and a binder
- a second aspect of this application provides an electrical device.
- the electrical equipment includes the battery provided in the first aspect of this application.
- Figure 1 is a schematic structural diagram of a battery according to an embodiment of the present application.
- Figure 2 is a schematic structural diagram of electrical equipment according to an embodiment of the present application.
- the active material in the positive electrode material layer and the negative electrode material layer expands in volume, the distance between the electrode plates is reduced, and part of the electrolyte is squeezed out.
- the volume of the above-mentioned active material shrinks, the distance between the electrode pieces will increase, and the electrolyte will flow back into the space between the electrode pieces.
- the return flow of the electrolyte is always not timely, resulting in some electrodes in the battery core not being able to contact the electrolyte, resulting in local lithium precipitation and affecting the safety of the battery.
- the battery 10 includes a positive electrode piece 110 , a negative electrode piece 120 , an electrolyte 130 and a separator 140 located between the positive electrode piece 110 and the negative electrode piece 120 .
- the positive electrode sheet 110 includes a positive electrode current collector 111 and a positive electrode material layer 112 disposed on the positive electrode current collector 111
- the negative electrode sheet 120 includes a negative electrode current collector 121 and a negative electrode material layer 122 disposed on the negative electrode current collector 121 .
- the positive electrode piece, the negative electrode piece and the electrolyte satisfy the following relationship:
- Ce represents the electrolyte retention capacity of the positive electrode piece and the negative electrode piece.
- the value range of Ce is 1.0g/Ah-5.0g/Ah; A is the correction factor; a is the viscosity of the electrolyte at room temperature.
- the unit is mPa ⁇ s; R is the capacity of the battery, the unit is Ah; B i is the capillary index of the pore diameter of the positive electrode material layer, B ii is the capillary index of the pore diameter of the negative electrode material layer, the units of Bi and B ii are both m; m represents the maximum pore diameter within the pore diameter interval of the positive electrode material layer, i is the positive electrode The average pore diameter of different pore diameter intervals of the material layer, Pc i is the ratio of the pore diameter volume in the positive electrode material layer when the pore diameter is i to the volume of the positive electrode material layer; n represents the maximum pore diameter in the pore diameter interval of the negative electrode material layer, ii is the average pore diameter in different pore diameter intervals of the negative electrode material layer, Pa ii is the ratio of the pore volume in the negative electrode material layer when the pore diameter is ii to all volumes of the negative electrode material layer; where i and ii can be the same,
- the ability of the positive electrode piece and the negative electrode piece to retain the electrolyte can be greatly improved (that is, the interaction force between the electrode piece and the electrolyte is improved).
- the viscosity of the electrolyte and the pore structure of the positive and negative electrode pieces satisfy the above relationship, it can not only improve the penetration of the electrolyte into the electrode piece, but also make the electrolyte in the pores of the electrode piece less susceptible to volume expansion of the active material.
- the generated squeezing force causes the electrolyte to be extruded from the electrode piece, which to a large extent avoids electrolyte overflow caused by the volume expansion of the electrode piece during battery charging and discharging.
- the battery provided by this application can significantly reduce the problem of lithium precipitation on the surface of the electrodes caused by partial electrode plates not being able to contact the electrolyte due to untimely return of the electrolyte, thereby ensuring that the battery has good cycle stability and safety. , exerting higher capacity.
- i and ii can be the same, and m and n can also be the same; the units of B i and B ii are both m; among them, the value range of Ce is 1.0g/Ah-5.0g/Ah.
- i is the average pore diameter of different pore diameter intervals of the positive electrode material layer
- ii is the average pore diameter of different pore diameter intervals of the negative electrode material layer.
- i and ii can be equal and both are positive integers.
- m is the maximum value in the aperture interval of the positive electrode piece
- n is the maximum value in the aperture interval of the negative electrode piece.
- Pc i is the pore diameter proportion corresponding to the average pore diameter in different pore diameter intervals of the positive electrode piece
- Pa ii is the pore diameter proportion corresponding to the average pore diameter in different pore diameter intervals of the negative electrode piece.
- i, ii, Pc i and Pa ii are related to the preparation conditions of the electrode pole pieces, such as the compaction density of the active material, particle engineering and/or parameters in the pole piece coating process, and the rolling process.
- Bi and Bii are related to the electrolyte composition and the starting and ending values of the pore diameter interval. Therefore, in the same pore diameter interval, the Bi value of the positive electrode material layer is equal to the Bii value of the negative electrode material layer.
- the positive electrode piece and the negative electrode piece may be collectively referred to as electrode pieces.
- the pore diameter refers to the pores between the particles in the positive electrode material layer or the negative electrode material layer.
- the pore diameter interval refers to the value range of the pore diameter.
- the pore size volume refers to the volume corresponding to a specific pore diameter.
- the value a is the actual measured value, which is the viscosity of the electrolyte at room temperature measured by a viscometer.
- the viscometer may be an Ubbelohde viscometer or a rotational rheometer, which is not limited in this application. It should be noted that the viscosity in this application refers to the property of a fluid that resists deformation or prevents relative movement of adjacent fluid layers.
- i, ii, Pc i and Pa ii of the electrode pole pieces can also be obtained through testing.
- the mercury pressure method was first used to measure the pore diameter and distribution of the above-mentioned positive and negative electrode pieces. Since the aperture interval range is large, and the B i value is different when the aperture value is at a lower value, will be larger, so the values in the lower aperture range are denser.
- i and ii take the following values based on the porosity results of experimental tests: 20000nm, 18000nm, 15000nm, 12000nm, 10000nm, 7500nm, 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm ,500nm,320nm , 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm, 20nm.
- mercury porosimetry relies on external pressure to cause mercury to overcome surface tension and enter the pores to measure the pore diameter and pore distribution.
- Porosity refers to the percentage of the volume of pores in a material to the total volume of the material in its natural state.
- the inventor of the present application found through a large number of experiments that the correction factor A is related to the material composition of the battery system, but A does not change with changes in the pore structure of the electrode pole piece. The larger the value of A, the stronger the interaction between the electrolyte and the positive and negative electrode plates.
- the above correction factor A needs to be obtained through preliminary simulation experiments. When the preliminary simulation experiments are performed to fit the A value of a certain battery system (the battery is an entity), i, ii, B i , B ii , Pc i , Pa ii It is an actual measured value, and Ce is also an actual measured value (recorded as Ce').
- Ce' represents the actual electrolyte retention capacity of the electrode pole piece in the existing battery (that is, prepare a battery core with an opening and pour excess liquid into it. The electrolyte is placed under a certain high vacuum. After a period of time, the electrolyte content value in the battery is measured. The ratio of this value to the battery capacity is the electrolyte retention capacity of the electrode plate Ce'); By substituting the measured Ce' and i, ii, Bi , Bii , Pc i and Pa ii values into the above relational formula, the A value of the battery system can be obtained.
- the above relational formula provided in this application can be used to prepare a battery with a predetermined electrolyte holding capacity. Specifically, after obtaining the A value of a certain battery system, according to the desired Ce value (ie, preset value) of the battery to be designed, each can be calculated according to the above relational expression and combined with the actual measured values B i and B ii
- the pore parameters Pc i and Pa ii of the pole piece can be used to adjust the compaction density, particle engineering and/or pole piece coating process, rolling process, etc. of the positive and negative active materials during the preparation process of the positive and negative electrode pieces. Parameters to obtain electrode plates and batteries that meet the above pore structure. And the battery's set electrolyte retention capacity is basically consistent with its actual electrolyte retention capacity.
- the electrolyte retention capacity Ce of the battery electrode plate can be calculated. Then conduct electrochemical performance tests on the above-mentioned batteries (for example, capacity retention rate test, lithium evolution test, rate characteristic test, etc.) to establish the corresponding relationship between the electrochemical performance of the battery and the Ce value. Then, for other batteries in this series, you only need to estimate the Ce value of the battery to estimate the cycle life of the battery. In other cases, the pore structure of the electrode piece can be calculated by knowing the A value of the battery and the actual electrolyte holding capacity value Ce', and substituting them into the above relationship.
- the fitting of the correction factor A includes the following steps:
- A is in the range of 0.01s-100s. Controlling the value of A within this range will help ensure the electrolyte retention capacity of the electrode pole piece, thereby helping to provide a battery with good cycle stability, high capacity retention rate and long cycle life.
- R is in the range of 0.1Ah-300Ah. In some embodiments, R is in the range of 10Ah-200Ah. In other embodiments, R is in the range of 10Ah-100Ah.
- the above relational formula defined in this application has universal applicability to batteries with different capacities.
- the porosity of the positive electrode material layer is in the range of 10%-50%, and the porosity of the negative electrode material layer is in the range of 10%-70%.
- the porosity of the positive and negative electrode material layers may be the same or different. Controlling the pore diameters of the positive and negative electrode pieces within the above range will help improve the electrolyte retention capacity of the electrode pieces without affecting the performance of the positive and negative electrode pieces.
- the distribution range of the pore diameters of the positive electrode material layer and the negative electrode material layer is 20 nm-20000 nm.
- the actual distribution ranges of the pore sizes of the positive and negative electrode material layers may be the same or different. Controlling the pore diameters of the positive and negative electrode material layers within the above range is conducive to improving the electrolyte retention capacity of the electrode pieces, and is conducive to the construction of conductive networks on the positive and negative electrode pieces.
- the values of m and n are 20000 nm. Since the pore diameter interval range in the porosity test results is large, and the difference in B i value will be greater when the pore diameter value is at a lower value, the values in the lower pore diameter interval are denser. In some embodiments, the length of the pore size interval may range from 20 nm to 100 nm.
- the aperture interval length can take the following values: 20000nm, 18000nm, 15000nm, 12000nm, 10000nm, 7500nm, 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm, 500nm, 320nm, 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm, 20nm.
- a is in the range of 0.5mPa ⁇ s-50mPa ⁇ s.
- the value of a can be 0.5mPa ⁇ s, 1.0mPa ⁇ s, 2.0mPa ⁇ s, 3.0mPa ⁇ s, 4.0mPa ⁇ s, 5.0mPa ⁇ s, 6.0mPa ⁇ s, 7.0mPa ⁇ s, 8.0 mPa ⁇ s, 9.0mPa ⁇ s, 10.0mPa ⁇ s, 20mPa ⁇ s, 30mPa ⁇ s, 40mPa ⁇ s, 50mPa ⁇ s, etc.
- a is between 0.5mPa ⁇ s and 5mPa ⁇ s.
- a can be 0.5mPa ⁇ s, 1.5mPa ⁇ s, 2.5mPa ⁇ s, 3.5mPa ⁇ s, 4.5mPa ⁇ s, 5.0mPa ⁇ s, etc.
- Appropriate electrolyte viscosity is conducive to improving the electrolyte retention capacity of the electrode pole pieces, and is conducive to the infiltration of the positive and negative electrode pole pieces by the electrolyte to maintain the internal resistance of the battery core within a suitable range.
- the electrolyte solution includes an organic solvent and a lithium salt.
- Lithium salts include, but are not limited to, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxaloborate, lithium difluoroborate oxalate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, lithium difluorophosphate, 4, At least one kind of 5-dicyano-2-trifluoromethylimidazole lithium.
- Organic solvents include, but are not limited to, at least one of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (EMC).
- the electrolyte further includes a viscosity modifier.
- Viscosity modifiers include, but are not limited to, polyimide, polyvinylidene fluoride, and polyacrylic acid.
- the above-mentioned viscosity modifier is a high-viscosity inactive organic liquid.
- the addition of the viscosity modifier can adjust the viscosity of the electrolyte to a preset value without changing other components of the electrolyte to meet the design needs of the battery. .
- the positive electrode material layer includes a positive electrode active material, a conductive agent and a binder.
- the negative electrode material layer includes negative electrode active material, conductive agent and binder.
- Positive active materials, negative active materials, conductive agents, and binders are all materials commonly used by those skilled in the art.
- the positive active material includes, but is not limited to, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium cobalt oxide, lithium manganate, lithium nickel manganate, nickel cobalt manganese (NCM ), nickel cobalt aluminum (NCA), and at least one of lithium-rich manganese-based materials.
- the negative active material includes but is not limited to graphite, natural graphite, intermediate At least one of phase carbon microspheres and silicon carbon negative electrode materials.
- the above-mentioned conductive agent includes but is not limited to at least one of carbon nanotubes (CNT), carbon fiber (CF), carbon black (such as acetylene black, Ketjen black), furnace black and graphene.
- the above-mentioned binders include but are not limited to polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide ( At least one of PI), polyacrylic acid (PAA), polyacrylate, polyolefin (such as polyethylene, polypropylene, polystyrene), sodium carboxymethylcellulose (CMC) and sodium alginate.
- PVDF polyvinylidene fluoride
- PTFE polytetrafluoroethylene
- PVA polyvinyl alcohol
- SBR styrene-butadiene rubber
- PAN polyacryl
- the electrical equipment 1 includes the above-mentioned battery 10 .
- the electrical equipment can be a portable terminal (such as a mobile phone, a laptop, a tablet), or a powered vehicle, which is not limited in this application.
- the electrical equipment includes a load connected to the above-mentioned battery, which may be, for example, various components in a portable terminal or a motor in a powered vehicle. Batteries are used to power the above loads. Due to the use of the above-mentioned batteries, the above-mentioned electrical equipment has better endurance and safety performance.
- Preparing the cathode plate Prepare the cathode active slurry, mix the cathode active material (single crystal NCM811, D50 particle size is 3.87 ⁇ m) with a mass ratio of 94%, and the conductive agent (carbon black + CNT) with a mass ratio of 4% , the binder (PVDF) with a mass ratio of 2% and N-methylpyrrolidone (NMP) are evenly mixed to prepare a positive electrode active slurry.
- Use a coating machine to apply the prepared positive electrode active slurry on the positive electrode current collector aluminum foil, dry it, roll it, and die-cut it to obtain a positive electrode piece.
- Preparing the negative electrode sheet Prepare the negative active slurry, including 96% of the negative active material (graphite) by mass, 2% of the conductive agent (acetylene black) by mass, and 2% of the binder by mass. (PVDF) and NMP are mixed evenly to prepare a negative electrode active slurry.
- the prepared negative electrode active slurry is coated on the negative electrode current collector copper foil, dried, rolled and die-cut to obtain a negative electrode sheet.
- the positive electrode pieces, separators, and negative electrode pieces are alternately stacked together to prepare a dry battery core through lamination.
- the capacity R value of the cell is 9.2Ah, and the positive and negative electrode pieces are alternately isolated by separators.
- the dry battery core was packaged in an aluminum-plastic film outer package and dried. The electrolyte was injected into the battery, and the battery of Example 1 was obtained after formation, which was recorded as S1.
- the batteries of Examples 2-14 are respectively produced according to the proportions in Table 1, and the batteries of Examples 2-14 are marked as S2-S14 respectively.
- NCM811 is specifically LiNi 0.8 Co 0.1 Mn 0.1 O 2
- NCM622 is specifically LiNi 0.6 Co 0.2 Mn 0.2 O 2
- NCM523 is specifically LiNi 0.5 Co 0.2 Mn 0.3 O 2 .
- Example 1 the batteries of Comparative Examples 1-3 were respectively produced according to the proportions in Table 2, and the batteries of Comparative Examples 1-3 were recorded as DS1-DS3 respectively.
- Lithium deposition detection Conduct a 0.5C/0.5C cycle test on the battery at 25°C with a voltage range of 2.5-4.2V. Record the lithium deposition on the negative electrode of the battery after 500 cycles. The results are summarized in Table 3.
- batteries S1-S14 in the examples all have good capacity retention rates.
- DS1 uses an electrolyte with too low viscosity, and the Ce value of DS1 is too small, so the battery The lithium precipitation situation is serious and the battery capacity declines rapidly.
- the Ce value of battery DS2 exceeds the upper limit defined in this application, and the internal resistance of the battery is large, resulting in a very low capacity retention rate of the battery under a high-rate 5C current.
- the porosity of the DS3 electrode plate is too small, resulting in a small Ce value, which leads to serious lithium deposition in the battery and rapid battery capacity decay.
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Abstract
提供了一种电池及用电设备。该电池中正、负极极片与电解液之间满足（aa），其中，Ce代表正极极片和负极极片对电解液的保液能力，A为校正因子，a为电解液在室温下的粘度，R为电池的容量，Bi及Bii分别为正极材料层及负极材料层的孔径的毛细管指数，i、ii分别为正、负极材料层的不同孔径区间的孔径均值，m、n分别代表正、负极材料层的孔径区间内的最大值，Pci、Paii分别为正、负极材料层中，在孔径为i、ii时的孔径体积与正、负极材料层的所有孔径体积占比。该电池具有良好的循环稳定性、较高的容量保持率。
Description
本申请要求于2022年3月15日提交中国专利局、申请号为202210251599.0、申请名称为“一种电池及电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
本申请涉及锂电池技术领域，具体涉及一种电池及用电设备。
锂电池在充放电过程中，正极极片和负极极片均会发生不同程度的体积变化，这种体积变化会导致电解液从电芯的极片间挤出以及电解液回流。但电解液回流不及时的现象时常发生，尤其是诸如卷绕电池及叠片电池等这种体积较大的电池，其电解液回流不及时的现象更为严重。而电解液回流不及时会造成电芯内的部分极片接触不到电解液，从而导致电极极片在放电过程中发生局部析锂，甚至产生安全隐患。
目前，业界常通过调节电解液的成分以提高电解液与电极极片之间的作用力来解决上述问题，但电解液与电极极片类型的适配度要求高，此法不具有广泛性和普适性。
发明内容
鉴于此，本申请通过调节正极极片及负极极片的孔径及各自孔径分布，并控制正极极片和负极极片与电解液的粘度之间满足一定的要求，可保证正极极片和负极极片具有较强的电解液保液能力、在充电时不易析锂，从而使得电池具有良好的循环稳定性、较高的容量保持率、及较长的电池循环寿命。
本申请第一方面提供了一种电池。该电池包括正极极片、负极极片、电解液及位于所述正极极片与负极极片之间的隔膜，所述正极极片包括正极集流体和设置在所述正极集流体上的正极材料层，所述负极极片包括负极集流体和设置在所述负极集流体上的负极材料层，所述正极极片、所述负极极片与所述电解液满足以下关系式：
其中，Ce代表所述正极极片和负极极片对所述电解液的保液能力，Ce的取值范围为1.0g/Ah-5.0g/Ah；A为校正因子；a为所述电解液在室温下的粘度，单位为mPa·s；R为所述电池的容量，单位为Ah；Bi为所述正极材料层的孔径的毛细管指数及Bii为所述负极材料层的孔径的毛细管指数，Bi和Bii的单位为m；m代表所述正极材料层的孔径区间内的孔径最大值，i为所述正极材料层的不同孔径区间的孔径均值，Pci为所述正极材料层中，在孔径为i时的孔径体积与所述正极材料层的体积的比值；n代表所述负极材料层的孔径区间内的孔径最大值，ii为所述负极材料层的不同孔径区间的孔径均值，Paii为所述负极材料层中，在孔径为ii时的孔径体积与所述负极材料层的体积的比值。
可选地，R在0.1Ah-300Ah的范围内，以及A在0.01s-100s的范围内。
可选地，R在10Ah-200Ah的范围内。
可选地，R在10Ah-100Ah的范围内。
可选地，所述正极材料层的孔径的分布范围是20nm-20000nm，以及所述负极材料层的孔径的分布范围是20nm-20000nm。
可选地，i的取值为20000nm、18000nm、15000nm、12000nm、10000nm、7500nm、6500nm、
5500nm、5000nm、3500nm、2500nm、1800nm、1200nm、750nm、500nm、320nm、200nm、140nm、90nm、65nm、50nm、40nm、30nm和20nm；ii的取值为20000nm、18000nm、15000nm、12000nm、10000nm、7500nm、6500nm、5500nm、5000nm、3500nm、2500nm、1800nm、1200nm、750nm、500nm、320nm、200nm、140nm、90nm、65nm、50nm、40nm、30nm和20nm。
可选地，所述正极材料层的孔隙率在10％-50％的范围内，以及所述负极材料层的孔隙率在10％-70％的范围内。
可选地，i的最小值及ii的最小值均为50，以及m的值及n的值均为20000nm。
可选地，a在0.5mPa·s-50mPa·s的范围内。
可选地，a在0.5mPa·s-5mPa·s的范围内。
可选地，所述电解液包括有机溶剂及锂盐，其中，所述锂盐包括六氟磷酸锂、四氟硼酸锂、二草酸硼酸锂、草酸二氟硼酸锂、双氟磺酰亚胺锂、双三氟甲基磺酰亚胺锂、二氟磷酸锂、4,5-二氰基-2-三氟甲基咪唑锂中的至少一种；所述有机溶剂包括碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯、甲基乙基碳酸酯中的至少一种。
可选地，所述电解液中包括粘度调节剂，所述粘度调节剂包括聚酰亚胺、聚偏氟乙烯、聚丙烯酸中的至少一种。
可选地，所述正极材料层包括正极活性材料层、导电剂和粘结剂；以及所述负极材料层包括负极活性材料、导电剂、和粘结剂。
本申请第二方面提供了一种用电设备。该用电设备包括本申请第一方面提供的电池。
图1是根据本申请实施例的电池的结构示意图。
图2是根据本申请实施例的用电设备的结构示意图。
附图标记说明：
1-用电设备，10-电池，110-正极极片，111-正极集流体，112-正极材料层，120-负极极
片，121-负极集流体，122-负极材料层，130-电解液，140-隔膜，150-电池壳体。
1-用电设备，10-电池，110-正极极片，111-正极集流体，112-正极材料层，120-负极极
片，121-负极集流体，122-负极材料层，130-电解液，140-隔膜，150-电池壳体。
一般地，电池在充放电过程中，当正极材料层和负极材料层中的活性物质发生体积膨胀，导致电极极片间的间距减小，部分电解液被挤出。而上述活性物质发生体积收缩时，又会使得电极极片间的间距增大，电解液又回流至极片之间。但因电解液的流动特性等因素，电解液的回流总是不及时，进而造成电芯中部分电极极片接触不到电解液，从而发生局部析锂、影响电池使用安全。
为解决上述技术问题，本申请实施例提供了一种电池。如图1所示，电池10包括正极极片110、负极极片120、电解液130及位于正极极片110与负极极片120之间的隔膜140。正极极片110包括正极集流体111和设置在正极集流体111上的正极材料层112，以及负极极片120包括负极集流体121和设置在负极集流体121上的负极材料层122。正极极片和负极极片与电解液满足以下关系式：
其中，Ce代表正极极片和负极极片对电解液的保液能力，Ce的取值范围为1.0g/Ah-5.0g/Ah；A为校正因子；a为电解液在室温下的粘度，单位为mPa·s；R为电池的容量，单位为Ah；Bi
为正极材料层的孔径的毛细管指数，Bii为负极材料层的孔径的毛细管指数，Bi和Bii的单位均为m；m代表正极材料层的孔径区间内的孔径最大值，i为正极材料层的不同孔径区间的孔径均值，Pci为正极材料层中，在孔径为i时的孔径体积与正极材料层的体积的比值；n代表负极材料层的孔径区间内的孔径最大值，ii为负极材料层的不同孔径区间的孔径均值，Paii为负极材料层中，在孔径为ii时的孔径体积与负极材料层的所有体积的比值；其中，i与ii可以相同，以及m与n也可以相同。
本申请中，通过调控正极材料层的孔径i、负极材料层的孔径ii、正极材料层的孔径分布Pci、及负极材料层的孔径分布Paii，并使得这些参数与采用的电解液的粘度a之间满足上述关系式，可在很大程度上提高正极极片和负极极片对电解液的保液能力(即，提高了电极极片与电解液之间的相互作用力)。当电解液粘度与正、负极极片的孔隙结构满足上述关系式时，既可以提高电解液在电极极片中的渗透程度，还可以使得极片孔隙中的电解液不易因受到活性材料体积膨胀产生的挤压力而从电极极片中挤出，在很大程度上避免了电池充放电过程电极极片体积膨胀而导致的电解液外溢发生。即使有少量的电解液溢出电芯，因电极极片与电解液之间较强的相互作用力以及电解液自身的分子间作用力，也可使电解液及时地回流至电极极片之间。因此，本申请提供的电池可以显著减少因电解液回流不及时导致的部分电极极片接触不到电解液带来的极片表面析锂的问题，进而保证电池具有良好的循环稳定性及安全性，发挥出较高容量。
m代表正极材料层的孔径区间内的最大值，i为正极材料层的不同孔径区间的孔径均值，Pci为正极材料层中，在孔径为i时的孔径体积与正极材料层体积的比值；n代表负极材料层的孔径区间内的最大值，ii为负极材料层的不同孔径区间的孔径均值，Paii为负极材料层中，在孔径为ii时的孔径体积与负极材料层体积的比值；其中，i与ii可以相同，以及m与n也可以相同；Bi和Bii的单位均为m；其中，Ce的取值范围为1.0g/Ah-5.0g/Ah。
本申请中，i为正极材料层的不同孔径区间的孔径均值，ii为负极材料层的不同孔径区间的孔径均值。i与ii可相等且均为正整数。m是正极极片孔径区间内的最大值，n是负极极片孔径区间内的最大值。Pci为正极极片的不同孔径区间的孔径均值对应的孔径占比，Paii为负极极片的不同孔径区间的孔径均值对应的孔径占比。i、ii、Pci、Paii与电极极片的制备条件相关，例如活性材料的压实密度、颗粒工程和/或极片涂布工艺、辊压工艺中的各参数。Bi及Bii与电解液成分、以及孔径区间的起止值相关，因此，在相同的孔径区间内，正极材料层的Bi值与负极材料层的Bii值相等。需要说明的是，在本申请中，正极极片和负极极片可以统称为电极极片。孔径是指正极材料层或负极材料层中的颗粒之间的孔隙，孔径区间是指孔径的直径的取值范围，孔径体积是指特定孔径对应的体积。
上述关系式中，a值为实测值，是由粘度计测得的电解液在室温下的粘度。示例性地，粘度计可以是乌式粘度计，也可以是旋转流变仪等，本申请不做限定。需要说明的是，本申请的粘度是指流体抵抗变形或阻止相邻流体层产生相对运动的性质。
由于在电解液成分和极片成分不变的条件下，Bi(或Bii)值与孔径值di成倒数关系:Bi＝k/di，所以通过实验获取两组以上的di-Bi值，拟合出对应的倒数关系得到k值，进而求出其它孔径值下的Bi(或Bii)值。具体地，选取三组不同直径(2μm、10μm、20μm)的毛细管，将其插入选定的电解液中，测得该电解液在毛细管内的上升高度，该高度值即为相应孔径的Bi值，得到k1，k2，k3，取均值为k值。再将不同di值代入关系式中得到对应的Bi值。
此外，电极极片的i、ii、Pci、Paii也可以通过测试得到。具体地，首先采用汞压法测量上述正、负极极片的孔径及其分布。由于孔径区间范围较大，且孔径值在更低值时Bi值差异
会更大，所以更低的孔径区间取值更密集。具体实施方式中，i、ii根据实验测试的孔隙率结果取如下值：20000nm、18000nm、15000nm、12000nm、10000nm、7500nm、6500nm、5500nm、5000nm、3500nm、2500nm、1800nm、1200nm、750nm、500nm、320nm、200nm、140nm、90nm、65nm、50nm、40nm、30nm、20nm。需要说明的是，压汞法是依靠外加压力使汞克服表面张力进入气孔来测定的气孔孔径和气孔分布。孔隙率是指材料中孔隙的体积与材料在自然状态下总体积的百分比。
本申请发明人通过大量实验发现，校正因子A与电池体系的材料组成相关，但A不随电极极片孔隙结构的变化而变化。A的值越大说明电解液与正、负极极片的作用力越强。上述校正因子A需要经过前期的模拟实验拟合得到，当对某个电池体系进行前期模拟实验拟合A值时(电池为实体)，i、ii、Bi、Bii、Pci、Paii为实测值，Ce也为实测值(记作Ce')，Ce'代表已有电池中电极极片的实际电解液保液能力(即，制备一个具有开口的电芯，往其中灌入过量的电解液并使其处于一定的高真空度下，一段时间后，测定电池中电解液的含量值，该值与电池容量的比即为电极极片的电解液保液能力Ce')；再将测得的Ce'与i、ii、Bi、Bii、Pci、Paii值代入上述关系式中，即可得到该电池体系的A值。
本申请提供的上述关系式可用于制备具有预定电解液保液能力的电池。具体地，在得到某个电池体系的A值后，根据待设计的电池想要的Ce值(即，预设值)，可根据上述关系式，结合实测值Bi、Bii，计算得到各极片的孔隙参数Pci、Paii，从而可在正、负极极片制备过程中，通过调控正、负极活性材料的压实密度、颗粒工程和/或极片涂布工艺、辊压工艺等参数，来得到满足上述孔隙结构的电极极片和电池。且该电池的设定电解液保液能力与其实际电解液保液能力基本一致。
此外，对于已有的电池体系来说，在测得Bi、Bii，了解电池的相关参数(A、i、ii、Pci、Paii)的情况下，并将它们代入上述关系式中，即可计算出电池电极极片的电解液保液能力Ce。再对上述电池进行电化学性能测试(例如，容量保持率测试、析锂情况检测、倍率特性测试等)，建立电池的电化学性能与Ce值之间的对应关系。那么，对于该系列的其他电池来说，只需预算出电池的Ce值，即可预估该电池的循环寿命。在另一些情况下，掌握了电池的A值以及实际的电解液保液能力值Ce'，并将其代入上述关系式中，即可计算得到电极极片的孔隙结构。
具体地，校正因子A的拟合包括以下步骤：
首先通过调节电池正、负极极片制备过程中正、负极活性材料的压实密度、颗粒工程和/或极片涂布工艺、辊压工艺中的各参数，制备出五组具有不同孔隙结构的正、负极极片，再进行以下测试：
(1)测定Bi及Bii值。
(2)测定五组电极极片的i、ii、Pci、Paii值。
(3)将上述正极极片、隔膜、上述负极极片依次叠放，在手套箱中进行组装，制备成五个电芯样品，并测量上述电芯中电极极片的电解液保液能力。需要注意的是，在上述测试中，除正、负极材料层的孔径及其分布为变量外，其余所有条件均保持一致。具体地，包括以下步骤：
在电芯外壳上开一个具有一定尺寸的洞，称重记录其质量为M1，再注入该条件下过量的电解液，然后在固定真空条件下抽真空2min，最后密封并称重记录其质量为M2；将测试样品内电解液质量记作Y，Y＝M2-M1，并计算Y/M的值，其中，M为正极极片和负极极片中正极材料层和负极材料层的质量之和；Y/M的值即为该电极极片的电解液保液能力Ce'。
(4)将上述5个电池样品的Ce'值代入前述关系式，计算得到在该实验条件下的各校正因子A值，则得到该电池体系的A值，五组A值在误差范围内大致相同。
本申请实施方式中，A在0.01s-100s的范围内。控制A的值在该范围内，有利于保证电极极片的电解液保液能力，从而有利于提供具有良好的循环稳定性、较高的容量保持率及较长的循环寿命的电池。
本申请实施方式中，R在0.1Ah-300Ah的范围内。一些具体实施例中，R在10Ah-200Ah的范围内。另一些具体实施例中，R在10Ah-100Ah的范围内。本申请限定的上述关系式对于不同容量的电池具有普适性。
本申请实施方式中，正极材料层的孔隙率在10％-50％的范围内，负极材料层的孔隙率各在10％-70％的范围内。其中，正、负极材料层的孔隙率可以相同，也可以不同。控制正、负极极片的孔径在上述范围内，有利于提高电极极片的电解液保液能力，且不会影响正、负极极片性能的发挥。
本申请实施方式中，正极材料层及负极材料层的孔径的分布范围是20nm-20000nm。正、负极材料层的孔径的实际分布范围可以相同，也可以不同。将正、负极材料层的孔径控制在上述范围内，有利于提高电极极片的电解液保液能力，并且有利于正、负极极片上的导电网络的构建。
本申请实施方式中，m及n的值为20000nm。由于孔隙率测试结果中的孔径区间范围较大，且孔径值在更低值时Bi值差异会更大，所以更低的孔径区间取值更密集。在一些实施方式中，孔径区间的长度可以是20nm-100nm。示例性地，孔径区间长度可以取如下值：20000nm、18000nm、15000nm、12000nm、10000nm、7500nm、6500nm、5500nm、5000nm、3500nm、2500nm、1800nm、1200nm、750nm、500nm、320nm、200nm、140nm、90nm、65nm、50nm、40nm、30nm、20nm。
本申请实施方式中，a在0.5mPa·s-50mPa·s的范围内。示例性地，a的值可以为0.5mPa·s、1.0mPa·s、2.0mPa·s、3.0mPa·s、4.0mPa·s、5.0mPa·s、6.0mPa·s、7.0mPa·s、8.0mPa·s、9.0mPa·s、10.0mPa·s、20mPa·s、30mPa·s、40mPa·s、50mPa·s等。一些实施方式中，a在0.5mPa·s-5mPa·s。示例性地，a可以为0.5mPa·s、1.5mPa·s、2.5mPa·s、3.5mPa·s、4.5mPa·s、5.0mPa·s等。合适的电解液粘度有利于提高电极极片的电解液保液能力，且有利于电解液对正、负极极片的浸润以维持电芯的内阻在合适的范围内。
本申请实施方式中，电解液包括有机溶剂及锂盐。锂盐包括但不限于六氟磷酸锂、四氟硼酸锂、二草酸硼酸锂、草酸二氟硼酸锂、双氟磺酰亚胺锂、双三氟甲基磺酰亚胺锂、二氟磷酸锂、4,5-二氰基-2-三氟甲基咪唑锂中的至少一种。有机溶剂包括但不限于碳酸乙烯酯(EC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、甲基乙基碳酸酯(EMC)中的至少一种。
本申请实施方式中，电解液中还包括粘度调节剂。粘度调节剂包括但不限于聚酰亚胺、聚偏氟乙烯、聚丙烯酸。上述粘度调节剂为高粘度的非活性有机液体，粘度调节剂的加入，能够在不改变电解液其他组分的情况下，将电解液的粘度调节至预设的值，来满足电池的设计需要。
本申请实施方式中，正极材料层包括正极活性材料、导电剂和粘结剂。负极材料层包括负极活性材料、导电剂和粘结剂。正极活性材料、负极活性材料、导电剂、粘结剂均为本领域技术人员常用的材料。示例性地，正极活性材料包括但不限于磷酸铁锂、磷酸锰锂、磷酸锰铁锂、磷酸钒锂、磷酸钴锂、钴酸锂、锰酸锂、镍锰酸锂、镍钴锰(NCM)、镍钴铝(NCA)、富锂锰基材料中的至少一种。示例性地，负极活性材料包括但不限于石墨、天然石墨、中间
相碳微球、硅碳负极材料中的至少一种。
上述导电剂包括但不限于碳纳米管(CNT)、碳纤维(CF)、炭黑(如乙炔黑、科琴黑)、炉黑及石墨烯中的至少一种。上述粘结剂包括但不限于聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇(PVA)、丁苯橡胶(SBR)、聚丙烯腈(PAN)、聚酰亚胺(PI)、聚丙烯酸(PAA)、聚丙烯酸酯、聚烯烃(如聚乙烯、聚丙烯、聚苯乙烯)、羧甲基纤维素钠(CMC)和海藻酸钠中的至少一种。
相应地，本申请实施例还提供了一种用电设备。如图2所示，用电设备1包括上述的电池10。该用电设备可以是便携式的终端(如手机、笔记本电脑、平板电脑)，也可以是动力车辆，本申请不做限定。该用电设备包括与上述电池连接的负载，例如，可以是便携式终端中的各种元器件，或者动力车辆中的马达等。电池用于为上述负载供电。由于采用了上述电池，上述用电设备具有较好的续航能力和安全性能。
下面分多个实施例对本申请技术方案进行详细说明。
实施例1
制备电解液：将EC、DMC、DEC以4：3：3的比例混合后，加入一定量的LiPF6，使得混合液中LiPF6的浓度为1mol/L。再加入一定量的粘度调节剂(聚酰亚胺)，得到电解液。通过粘度计测试电解液在室温下的粘度值a。取孔径的区间长度为50nm，测定Bi值，Bi＝Bii。
制备正极极片：配制正极活性浆料，将质量占比为94％的正极活性材料(单晶NCM811，D50粒径为3.87μm)，质量占比为4％的导电剂(炭黑+CNT)，质量占比为2％的粘结剂(PVDF)与N-甲基吡咯烷酮(NMP)混合均匀，制备得到正极活性浆料。使用涂布机，将制备的正极活性浆料涂敷在正极集流体铝箔上，烘干后进行辊压，模切，得到正极极片。
制备负极极片：配制负极活性浆料，将质量占比为96％的负极活性材料(石墨)，质量占比为2％的导电剂(乙炔黑)，质量占比为2％的粘结剂(PVDF)与NMP混合均匀，制备得到负极活性浆料。将制备的负极活性浆料涂敷在负极集流体铜箔上，烘干后进行辊压，模切，得到负极极片。
测定电极极片的孔隙结构：采用压汞法测定上述正、负极极片的i、ii、Pci、Paii值，并计算
的值。(Q值的范围为10m-200m)，测试方法具体结果如下(以电池编号S1为例)：
将正极极片、隔膜、和负极极片一起交替层叠，通过叠片方式制得干电芯，电芯的容量R值为9.2Ah，其中正、负极极片之间被隔膜交替隔离。将干电芯置于铝塑膜外包装中封装并烘干，注入电解液，经化成后得到实施例1的电池，记作S1。
按照实施例1提供的电池制作方法，按表1的配比分别制作实施例2-14的电池，并将实施例2-14的电池分别记作S2-S14。
表1实施例电池S1-S14的各参数
其中，NCM811具体为LiNi0.8Co0.1Mn0.1O2，NCM622具体为LiNi0.6Co0.2Mn0.2O2，以及NCM523具体为LiNi0.5Co0.2Mn0.3O2。
为突显本申请实施例的有益效果，设置以下3个对比例。按照实施例1提供的电池制作方法，按表2的配比分别制作对比例1-3的电池，并将对比例1-3的电池分别记作DS1-DS3。
表2对比例电池DS1-DS3的各参数
对上述各实施例及各对比例制得的电池进行电化学性能测试，具体包括：
(1)析锂情况检测：在25℃下对电池进行0.5C/0.5C循环测试，电压范围为2.5-4.2V，记录循环500圈后电池负极的析锂情况，结果汇总在表3中。
(2)循环性能测试：在25℃下对电池进行0.5C/0.5C循环测试，电压范围为2.5-4.2V，
记录循环500圈后电池的容量保持率，结果汇总在表3中。
(3)大电流性能测试：在25℃下对电池进行大电流充放电测试，电压范围为2.5-4.2V，采用5C/5C的大电流进行充放电，记录电池的容量保持率，结果汇总在表3中。
表3各实施例及对比例制得的电池的电化学性能测试结果汇总
结合表1-2中电池的参数以及表3中各电池的测试结果可以看出，符合本申请限定的关系式的电池，其各电化学性能均较优异。具体地，实施例电池S1-S14均具有较好的容量保持率，对比电池S1和电池DS1，在同样的实验条件下，DS1采用粘度过低的电解液，DS1的Ce值过小，因而电池析锂情况严重，电池容量衰减较快。对比电池S1和电池DS2，电池DS2的Ce值超过了本申请限定的上限，电池的内阻较大，从而导致电池在高倍率5C电流下的容量保持率非常低。而对比电池S1和电池DS3，在同样的实验条件下，DS3电极极片的孔隙率过小导致Ce值偏小，从而导致电池析锂严重，电池容量衰减快。
以上所述是本申请的示例性实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请原理的前提下，还可以对其做出若干改进和润饰，这些改进和润饰也视为本申请的保护范围。
Claims (12)
- 一种电池(10)，其特征在于，所述电池包括正极极片(110)、负极极片(120)、电解液(130)及位于所述正极极片与负极极片之间的隔膜(140)，所述正极极片包括正极集流体(111)和设置在所述正极集流体上的正极材料层(112)，所述负极极片包括负极集流体(121)和设置在所述负极集流体上的负极材料层(122)，所述正极极片、所述负极极片与所述电解液满足以下关系式：
其中，Ce代表所述正极极片和负极极片对所述电解液的保液能力，Ce的取值范围为1.0g/Ah-5.0g/Ah；A为校正因子；a为所述电解液在室温下的粘度，单位为mPa·s；R为所述电池的容量，单位为Ah；Bi为所述正极材料层的孔径的毛细管指数及Bii为所述负极材料层的孔径的毛细管指数，Bi和Bii的单位均为m；m代表所述正极材料层的孔径区间内的孔径最大值，i为所述正极材料层的不同孔径区间的孔径均值，Pci为所述正极材料层中，在孔径为i时的孔径体积与所述正极材料层体积的比值；n代表所述负极材料层的孔径区间内的孔径最大值，ii为所述负极材料层的不同孔径区间的孔径均值，Paii为所述负极材料层中，在孔径为ii时的孔径体积与所述负极材料层体积的比值。 - 根据权利要求1所述的电池，其特征在于，R在0.1Ah-300Ah的范围内，以及A在0.01s-100s的范围内。
- 根据权利要求1或2所述的电池，其特征在于，R在10Ah-100Ah的范围内。
- 根据权利要求1-3中任一项所述的电池，其特征在于，所述正极材料层的孔径的分布范围是20nm-20000nm，以及所述负极材料层的孔径的分布范围是20nm-20000nm。
- 根据权利要求1-4中任一项所述的电池，其特征在于，所述正极材料层的孔隙率在10％-50％的范围内，以及所述负极材料层的孔隙率在10％-70％的范围内。
- 根据权利要求1-5中任一项所述的电池，其特征在于，i的最小值及ii的最小值均为50，以及m的值及n的值均为20000nm。
- 根据权利要求1-6中任意一项所述的电池，其特征在于，i的取值为20000nm、18000nm、15000nm、12000nm、10000nm、7500nm、6500nm、5500nm、5000nm、3500nm、2500nm、1800nm、1200nm、750nm、500nm、320nm、200nm、140nm、90nm、65nm、50nm、40nm、30nm和20nm；ii的取值为20000nm、18000nm、15000nm、12000nm、10000nm、7500nm、6500nm、5500nm、5000nm、3500nm、2500nm、1800nm、1200nm、750nm、500nm、320nm、200nm、140nm、90nm、65nm、50nm、40nm、30nm和20nm。
- 根据权利要求1-7任一项所述的电池，其特征在于，a在0.5mPa·s-50mPa·s的范围内。
- 根据权利要求1-8任一项所述的电池，其特征在于，所述电解液包括有机溶剂及锂盐，其中，所述锂盐包括六氟磷酸锂、四氟硼酸锂、二草酸硼酸锂、草酸二氟硼酸锂、双氟磺酰亚胺锂、双三氟甲基磺酰亚胺锂、二氟磷酸锂、4,5-二氰基-2-三氟甲基咪唑锂中的至少一种；所述有机溶剂包括碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯、甲基乙基碳酸酯中的至少一种。
- 根据权利要求1-9任一项所述的电池，其特征在于，所述电解液中包括粘度调节剂，所述 粘度调节剂包括聚酰亚胺、聚偏氟乙烯、聚丙烯酸中的至少一种。
- 根据权利要求1-10任一项所述的电池，其特征在于，所述正极材料层包括正极活性材料层、导电剂、和粘结剂；以及所述负极材料层包括负极活性材料、导电剂、和粘结剂。
- 一种用电设备(1)，其特征在于，所述用电设备包括如权利要求1-11任一项所述的电池(10)。
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| CN110579569A (zh) * | 2019-09-12 | 2019-12-17 | 东莞维科电池有限公司 | 一种电池中电解液保液量的计算方法 |
| CN111403801A (zh) * | 2020-03-23 | 2020-07-10 | 孚能科技(赣州)股份有限公司 | 一种锂离子电池及其制备方法 |
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| CN110579569A (zh) * | 2019-09-12 | 2019-12-17 | 东莞维科电池有限公司 | 一种电池中电解液保液量的计算方法 |
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