Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. 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.
Fig. 1 is a schematic structural view of a current collector according to some embodiments of the present invention; fig. 2 is a schematic structural view of a current collector according to other embodiments of the present invention. As shown in fig. 1 or fig. 2, the present invention provides a current collector, which includes an intermediate layer 1 and a conductive layer 2 disposed on at least one functional surface of the intermediate layer 1;
wherein the resistivity ρ of the conductive layer 2 and the intrinsic resistivity ρ0 of the conductive layer 2 satisfy the following relationship;
1＜ρ/ρ0≤2。
in the present invention, the functional surface of the intermediate layer 1 means two surfaces of the intermediate layer 1 having the largest area and being disposed opposite to each other, and the functional surface of the intermediate layer 1 is used for disposing the conductive layer 2.
As shown in fig. 1, the current collector of the present invention can be obtained by providing a conductive layer 2 on any one of the functional surfaces of the intermediate layer 1. As shown in fig. 2, the current collector of the present invention can be obtained by providing conductive layers 2 on both functional surfaces of the intermediate layer 1.
In the present invention, the conductive layer 2 may be formed by disposing a conductive material on the functional surface of the intermediate layer 1 by at least one of mechanical roll lamination, thermal lamination, and adhesive lamination.
The intermediate layer 1 of the invention can improve the mechanical properties of the current collector, thereby prolonging the service life of the battery. The invention is not limited to the specific material of the intermediate layer 1, and any material capable of improving the mechanical properties of the current collector falls within the protection scope of the invention.
In the invention, the intrinsic resistivity of the conductive layer 2 is an inherent property of the conductive material and can be obtained by consulting the technical handbook for domestic and foreign use. The resistivity of the conductive layer 2 can be tested by a test method according to ASTM F390-2011, specifically, a digital four-probe tester model ST2253 of su lattice electronics limited.
In actual production, the intrinsic resistivity of the conductive layer may be different from the resistivity of the conductive layer. The inventors have conducted an analysis to consider that the reason why the intrinsic resistivity of the conductive layer differs from the resistivity of the conductive layer may be that: when the conductive material is processed into a conductive layer by at least one of mechanical rolling compounding, thermal compounding and bonding compounding, the microstructure of the conductive material is changed, and compared with the original conductive material, the microstructure of the formed conductive layer has partial defects, so that the compactness of the formed conductive layer is reduced, and the resistivity of the conductive layer is larger than the intrinsic resistivity of the conductive layer.
In the invention, the rho/rho0 meets the relation, so that the current collector not only can promote the transmission of electrons under normal conditions and improve the multiplying power performance of the battery, but also can fail a conductive layer in the current collector when the battery is subjected to extreme abuse such as needling and the like, and cut off the transmission of electrons and improve the safety performance of the battery. The current collector of the invention can lead the battery to have excellent safety performance and multiplying power performance.
In some embodiments of the present invention, the sheet resistance Rs of the conductive layer and the intrinsic sheet resistance Rs0 of the conductive layer satisfy the following relationship;
1＜Rs/Rs0≤2。
In the invention, Rs = ρ/h, formula (1); rs0＝ρ0/h, formula (2); h is the thickness of the conductive layer.
Further, Rs/Rs0 can be 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0.
In some embodiments, a conductive layer with superior mechanical properties may be further selected in order to extend the service life of the current collector, for example, a conductive layer that does not crack on the surface after rolling under a constant pressure of 50 tons may be selected.
In the invention, as Rs/Rs0 meets the relation, the prepared current collector can further ensure that the battery has excellent safety performance and rate capability.
In some embodiments of the invention, Rs/Rs0 is less than or equal to 1.01 and less than or equal to 1.1 in order to further improve the multiplying power performance of the battery under the premise of ensuring the safety performance of the battery.
In some embodiments of the invention, Rs of the conductive layer is 5mΩ -1000.1mΩ. When Rs of the conductive layer is within the above range, the battery has more excellent rate performance and safety performance.
Further, Rs of the conductive layer may be 5mΩ、6mΩ、7mΩ、8mΩ、9mΩ、10mΩ、15mΩ、20mΩ、30mΩ、40mΩ、50mΩ、60mΩ、70mΩ、80mΩ、90mΩ、100mΩ、200mΩ、300mΩ、400mΩ、500mΩ、600mΩ、700mΩ、800mΩ、900mΩ、1000mΩ.
In some embodiments of the invention, the conductive layer has a tensile elongation at break of 1% to 20%.
In the invention, the tensile elongation at break of the conductive layer refers to the ratio of the length increment before and after stretching to the length before stretching when the conductive layer is broken under the action of external force, and the tensile elongation at break of the conductive layer can be tested by referring to the content in the GB/T228.1-2010 metal material-tensile test. When the elongation at break of the conductive layer accords with the range, the current collector not only can cut off the internal current of the battery when the battery is in short circuit and improve the safety performance of the battery, but also has more excellent mechanical properties and can prolong the service life of the battery.
Further, the tensile elongation at break of the conductive layer may be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.
In some embodiments of the invention, the thickness of the conductive layer is 0.1 μm to 3 μm, the thickness of the intermediate layer is 0.5 μm to 40 μm, and the thickness of the current collector is 2 μm to 46 μm in order to balance the energy density and mechanical properties of the current collector.
Further, the thickness of the conductive layer may be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3 μm.
The thickness of the intermediate layer may be 0.5μm、0.6μm、0.7μm、0.8μm、0.9μm、1.0μm、1.5μm、2.0μm、2.5μm、3.0μm、3.5μm、4.0μm、4.5μm、5.0μm、6.0μm、7.0μm、8.0μm、9.0μm、10.0μm、20.0μm、30.0μm、40.0μm.
The thickness of the current collector may be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 20 μm, 30 μm, 40 μm, 46 μm.
In some embodiments of the invention, the material of the conductive layer is selected from metallic conductive materials.
The metal conductive material may be at least one selected from aluminum, copper, nickel, titanium, silver, nickel-copper alloy, aluminum-zirconium alloy, and stainless steel.
In some embodiments of the present invention, the material of the intermediate layer is selected from at least one of an insulating polymer material, an insulating polymer composite material, a conductive polymer material, and a conductive polymer composite material.
In the present invention, the insulating polymer material may be at least one selected from the group consisting of polyethylene terephthalate, polyamide, polyimide (PI), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), poly (p-phenylene terephthalamide), polypropylene ethylene, an acrylonitrile-butadiene-styrene copolymer, polyvinyl formal, polyvinyl butyral, polyurethane, polyacrylonitrile, polyvinyl acetate, polyoxymethylene, phenolic resin, epoxy resin, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), silicone rubber, polycarbonate, polysulfone, polyethersulfone, polyphenylene oxide, polyetheretherketone, poly (p-phenylene benzobisoxazole), aramid, polybenzimidazole, polyaromatic oxadiazole, cellulose, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose. Further, the insulating polymer material may be at least one selected from polyimide, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyethylene, and polypropylene.
The insulating polymer composite material can be a composite material formed by an insulating polymer material and an inorganic material. Wherein the inorganic material is at least one selected from ceramic material, glass material and ceramic composite material.
The conductive polymer material may be selected from the group consisting of polysulfide and/or iodine doped polyacetylene. When the conductive polymer material is selected from polyacetylene doped with iodine, the invention is not limited to the doping amount of iodine, and can be selected according to practical application.
The conductive polymer composite material can be a composite material formed by insulating polymer material and conductive material. Wherein the conductive material is at least one selected from conductive carbon material, metal material and composite conductive material; the conductive carbon material is at least one of carbon black, carbon nano tube, graphite, acetylene black and graphene, the metal material is at least one of nickel, iron, copper, aluminum and alloys of the metals, and the composite conductive material is at least one of nickel-coated graphite powder and nickel-coated carbon fiber.
The molecular weight of the polymer is not particularly limited in the present invention.
The current collector can be used for preparing the pole piece, and the invention does not limit the electrical property of the pole piece, and can be a positive pole piece or a negative pole piece. When the positive plate is a positive plate, the structure of the positive plate comprises a positive current collector and a positive active layer arranged on at least one functional surface of the positive current collector; when the electrode plate is a negative electrode plate, the structure of the negative electrode plate comprises a negative electrode current collector and a negative electrode active layer arranged on at least one functional surface of the negative electrode current collector.
The positive electrode active material in the positive electrode active layer can be a positive electrode active material known in the art, and all positive electrode active materials capable of carrying out reversible intercalation or deintercalation of ions belong to the protection scope of the invention. For example, the positive electrode active material may be a lithium transition metal composite oxide, wherein the transition metal may be at least one of Mn, fe, ni, co, cr, ti, zn, V, al, zr, ce or Mg.
The lithium transition metal composite oxide can be doped with elements with large electronegativity, such as at least one of S, F, cl or I, so that the positive electrode active material has higher structural stability and electrochemical performance. Illustratively, the lithium transition metal composite oxide may be LiMn
2O
4、LiNiO
2、LiCoO
2、LiNi
1-yCo
yO
2(0<y<1)、LiNi
aCo
bAl
1-a-bO
2(0<a<1,0<b<1,0<a+b<1)、LiMn
1-m-nNi
mCo
nO
2(0<m<1,0<n<1,0<m+n<1)、LiMPO
4(M may be at least one of Fe, mn, or Co) or Li
3V
2(PO
4)
3.
The negative electrode active material in the negative electrode active layer can be a negative electrode active material known in the art, and all negative electrode active materials capable of carrying out reversible intercalation or deintercalation of ions belong to the protection scope of the invention. For example, the anode active material may be at least one of metallic lithium, natural graphite, artificial graphite, intermediate phase micro carbon spheres (MCMB), hard carbon, soft carbon, silicon-carbon composite, siO, li-Sn alloy, li-Sn-O alloy, sn, snO, snO2, spinel structured lithium titanate, or Li-Al alloy.
The active layer may further include a conductive agent. In some embodiments, the conductive agent is selected from at least one of a carbon material, a metal material, and a conductive polymer. Wherein the carbon material is at least one selected from graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; the metal material is selected from at least one of metal powder, metal fiber, copper, nickel, aluminum and silver; the conductive polymer is selected from polyphenylene derivatives.
The active layer may further include a binder. In some embodiments, the binder is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), aqueous acrylic, polyvinyl alcohol, polyvinyl butyral, polyurethane, fluorinated rubber, carboxymethyl cellulose (CMC), or polyacrylic acid (PAA).
The positive electrode sheet of the present invention may be prepared according to a conventional method in the art. Dispersing a positive electrode active material, a conductive agent and a binder in a solvent (N-methyl pyrrolidone can be adopted) to form uniform positive electrode active slurry, coating the positive electrode active slurry on a current collector, and drying to obtain a positive electrode plate containing a positive electrode active layer.
The negative electrode sheet of the present invention may be prepared according to a conventional method in the art. Dispersing a negative electrode active material, a conductive agent, a binder, a thickener and a dispersing agent in a solvent, wherein the solvent can be NMP or deionized water to form uniform negative electrode active slurry, coating the negative electrode active slurry on a current collector, and drying to obtain a negative electrode plate containing a negative electrode active layer.
In the preparation process of the above-mentioned electrode sheet, in order to enhance the binding force between the current collector and the active layer, the current collector may be subjected to treatments including, but not limited to, the following: at least one of perforating, etching, and coating the conductive substrate.
The pole piece provided by the invention comprises the current collector, so that the transmission of electrons can be promoted under normal conditions, the rate performance of the battery is improved, and when the battery is subjected to extreme misuse conditions such as needling, a conductive layer in the pole piece can fail, the transmission of electrons is cut off, and the safety performance of the battery is improved. The pole piece can enable the battery to have excellent safety performance and rate capability.
A second aspect of the present invention provides a battery comprising the current collector described above.
The battery of the present invention may be a primary battery, a secondary battery, a fuel cell, a solar cell, or a capacitor. Further, the battery may further include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, a lithium primary battery, a sodium ion battery, or a magnesium ion battery.
In a specific embodiment, the cell of the present invention comprises a positive plate, a negative plate, a separator, and an electrolyte. Wherein the positive electrode sheet and/or the negative electrode sheet comprises the current collector.
The separator of the present invention is not particularly limited, and any known porous separator having electrochemical stability and chemical stability may be used, and may be at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single layer or multiple layers.
In the present invention, the above-mentioned electrolytic solution includes an organic solvent and an electrolyte salt. Organic solvents as a medium for transporting ions in the electrochemical reaction, organic solvents for battery electrolytes known in the art may be used. As the source of ions, electrolyte salts known in the art for use in battery electrolytes may be employed.
The organic solvent may be at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene Carbonate (BC), fluoroethylene carbonate (FEC), methyl Formate (MF), methyl Acetate (MA), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), 1, 4-butyrolactone (GBL), sulfolane (SF), dimethylsulfone (MSM), methylsulfone (EMS), diethylsulfone (ESE). In a specific embodiment, two or more of the above organic solvents may be selected.
The electrolyte salt may be lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium difluorophosphate (LiPF2O2), lithium 4, 5-dicyano-2-trifluoromethylimidazole (LiDTI), lithium bis (oxalato) borate (LiBOB), lithium trifluoromethane sulfonate (LiTFS), lithium bis (malonic) borate (LiBMB), lithium difluorooxalato borate (lipfub), lithium bis (difluoromalonic) borate (LiBDFMB), lithium (malonato oxalato) borate (LiMOB), lithium tris (oxalato) phosphate (LiTOP), lithium tris (difluoromalonic) phosphate (litfmp), lithium tetrafluorooxalato phosphate (LiTFOP), lithium difluorodioxaoxalato phosphate (LiDFOP), lithium bis (fluorosulfonyl) imide (LiFSI), lithium bis (trifluoromethanesulfonyl imide) (lithio), lithium (fluoro (3) sulfonate) (Lihalo) or (Lihalo) is an integer of at least one of 35 to 38, and at least one of 35 (3, 38) is fluorinated (li) and (li (fluoro) is (n) fluoride (35, 35 (n) or (li (n) is fluorinated).
In the present invention, the electrolyte may further include an additive. The additive may be ethylene carbonate (VC), vinyl Ethylene Carbonate (VEC), 1, 3-propane sultone, fluoroethylene carbonate (FEC), trifluoromethylcarbonate, dimethyl sulfate, vinyl methyl sulfate, propylene sulfate, ethylene sulfite, succinic anhydride, biphenyl, diphenyl ether, toluene, xylene, cyclohexylbenzene, fluorobenzene, p-fluorotoluene, p-fluoroanisole, tert-butylbenzene, tert-pentylbenzene, propenolactone, butane sultone, methylene methane disulfonate, ethylene glycol bis (propionitrile) ether, hexamethyldisilazane, heptamethyldisilazane, dimethyl methylphosphonate, diethyl ethylphosphonate, trimethyl phosphate triethyl phosphate, triphenyl phosphite, tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, acetonitrile (AN), malononitrile, succinonitrile (SN), glutaronitrile (GN), adiponitrile (ADN), 1,3, 6-hexanetrinitrile, 1,3, 5-pentanetrimitrile, ethyleneglycol dipropionitrile ether, hexafluorocyclotriphosphazene, pentafluoroethoxycyclotriphosphazene, pentafluorophenoxycyclotriphosphazene, 1, 4-dicyano-2-butene, p-fluorobenzonitrile, p-methylbenzonitrile, 2-fluoroadiponitrile, 2-difluorosuccinonitrile, tricyanobenzene, acrylonitrile, crotononitrile, trans-butenedinitrile, trans-hexenedinitrile, 1, 2-bis (cyanoethoxy) ethane, 1,2, 3-tris (cyanoethoxy) propane, at least one of bis (cyanoethyl) sulfone and 3- (trimethylsiloxy) propionitrile.
In the invention, the positive plate, the diaphragm and the negative plate are sequentially stacked to obtain the battery cell, or the positive plate, the diaphragm and the negative plate are sequentially stacked and then wound to obtain the battery cell; the battery core is placed in a packaging shell, electrolyte is injected into the packaging shell, and the packaging shell is sealed, so that a battery can be prepared.
The battery provided by the invention has excellent multiplying power performance and excellent safety performance due to the fact that the current collector is included.
A third aspect of the invention provides an electronic device comprising a battery as described above.
The battery of the invention can be applied to various occasions to prepare electronic equipment. For example, the electronic device may be a mobile computer, a notebook computer, a portable telephone, an electronic book player, a portable facsimile machine, a portable copier, a portable printer, a headset, a video recorder, a liquid crystal television, a portable cleaner, a calculator, a memory card, a portable audio recorder, a radio, a backup power source, an automobile, a motorcycle, an electric ship, a bicycle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a camera, a household large-sized battery, an energy storage power station, or the like.
The electronic equipment provided by the invention has excellent multiplying power performance and excellent safety performance due to the battery.
The technical solutions of the present invention will be further described below with reference to specific examples, all parts, percentages, and ratios recited in the following examples are by weight, and all reagents used in the examples are commercially available or are synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the examples are commercially available.
Test examples C1 to C28
The current collectors of test examples C1-C28 were prepared by the following steps:
And respectively arranging conductive layers on the two functional surfaces of the middle layer according to a certain mode to obtain a current collector, wherein specific preparation parameters are shown in table 1.
TABLE 1
In Table 1, Rs＝ρ/h;Rs0＝ρ0/h, ρ is the resistivity of the conductive layer, ρ0 is the intrinsic resistivity of the conductive layer, and h is the thickness of the conductive layer. The intrinsic resistivity of the conductive layer is obtained by consulting the technical handbook for domestic and foreign use; the resistivity of the conductive layer was measured using a test method on the ASTM F390-2011 standard, specifically, using a digital four-probe tester model ST2253, sulse lattice electronics inc.
The tensile elongation at break of the conductive layer was tested using the metallic material-tensile test in GB/T228.1-2010.
The method for testing whether cracks exist on the surface of the rolled conductive layer comprises the following steps: and rolling the surface of the conductive layer by using a weight of 50 tons at a rolling speed of 1m/s, and observing whether cracks exist on the surface of the rolled conductive layer.
In Table 1, the weight average molecular weight of the polyurethane was 2 ten thousand, the weight average molecular weight of PET was 3 ten thousand, the weight average molecular weight of PBT was 2.5 ten thousand, the weight average molecular weight of PTFE was 2 ten thousand, the weight average molecular weight of PI was 4.5 ten thousand, and the weight average molecular weight of PP was 60 ten thousand.
Examples and comparative examples
The lithium ion batteries of examples 1 to 10 and comparative examples 1 to 2 were produced by a method comprising the steps of:
(1) Preparation of positive plate
Dispersing a nickel cobalt lithium manganate ternary material serving as an anode active material, a carbon black conductive agent and polyvinylidene fluoride (PVDF) serving as a binder in N-methyl pyrrolidone (NMP), uniformly stirring to obtain anode active slurry, coating the anode active slurry on the functional surface of an anode current collector in C1-C12, C25, C27, C29, C31 and C33, drying, rolling and cutting to obtain an anode sheet containing an anode active layer;
In the positive electrode active layer, the mass ratio of the nickel cobalt lithium manganate ternary material, the carbon black conductive agent and the polyvinylidene fluoride is 97:1.5:1.5.
(2) Preparation of negative plate
Dispersing graphite, carbon black conductive agent, binder Styrene Butadiene Rubber (SBR) and thickener sodium carboxymethylcellulose (CMC) serving as anode active materials in deionized water, uniformly stirring to obtain anode active slurry, coating the anode active slurry on the functional surface of an anode current collector in C13-C24, C26, C28, C30, C32 and C34, drying, rolling and cutting to obtain an anode sheet containing an anode active layer;
in the negative electrode active layer, the mass ratio of graphite to carbon black conductive agent to styrene-butadiene rubber to sodium carboxymethyl cellulose is 97:1:1:1.
(3) Electrolyte preparation
In a glove box filled with argon and having a water content of <5ppm, mixing Ethylene Carbonate (EC), propylene Carbonate (PC) and diethyl carbonate (DEC) according to a mass ratio of 0.5:1.5:1.5, adding LiPF6, stirring uniformly to form a basic electrolyte, wherein the concentration of LiPF6 in the basic electrolyte is 1.15mol/L, and finally adding 1% of VC additive and 1% of FEC additive into the basic electrolyte.
(4) Preparation of separator
A7-mu m wet polyethylene diaphragm is selected as a base material, an alumina ceramic coating with the thickness of 2 mu m is coated on one surface of the base material, PVDF-HFP adhesive layers with the thickness of 1 mu m are respectively coated on two sides of the diaphragm, and the diaphragm with the total thickness of 11 mu m is obtained and is cut into required widths for standby.
(5) Preparation of lithium ion batteries
And sequentially stacking the positive electrode, the diaphragm and the negative electrode, welding the electrode lugs and winding to obtain a winding core, placing the winding core in an aluminum plastic film outer package, injecting the electrolyte into the aluminum plastic film outer package, and performing the procedures of vacuum sealing, standing, formation, shaping and the like to obtain the lithium ion battery.
Specific preparation parameters are shown in Table 2.
Performance testing
The following performance tests were performed on the lithium ion batteries in examples and comparative examples, and the test results are shown in table 2.
1) Initial internal resistance
And placing the lithium ion battery in an environment of 25 ℃, discharging to a lower limit voltage (3.0V) at a constant current of 0.5 ℃, standing for 5 minutes, directly testing the ohmic impedance of the battery by an internal resistance tester, and setting the frequency of an alternating current signal to be 1KHz to obtain the initial internal resistance of the battery.
2) Rate discharge performance
Placing the lithium ion battery in an environment of 25 ℃, charging at a constant current of 0.2C to an upper limit voltage (4.3V) to a constant voltage until the current is reduced to 0.05C, standing for 5 minutes, discharging at a constant current of 0.2C to a lower limit voltage (3.0V), and recording a discharge capacity Q1; the above procedure was then repeated with the discharge current changed to 1.5C, the discharge capacity Q2 was recorded, and the 1.5C discharge capacity retention Φ=q2/Q1 ×100% was calculated.
3) Rate of passage of heating program
Taking 10 battery samples, referring to the method of section 6.2.6 in GB/T31485-2015, respectively carrying out heating item test on each battery, referring to section 5.1.5, judging the test result, if the battery does not explode or fire, the test is passed, otherwise, the test is not passed, and calculating the heating item passing rate of 10 batteries.
4) Extrusion item passage rate
Taking 10 battery samples, referring to the method of section 6.2.7 in GB/T31485-2015, respectively carrying out extrusion item test on each battery, referring to section 5.1.6, judging the test result, if the battery does not explode or fire, the test is passed, otherwise, the test is not passed, and calculating the extrusion item passing rate of 10 batteries.
5) Needling project
Taking 10 battery samples, referring to a method of 6.2.8 th section in GB/T31485-2015, respectively carrying out needling item test on each battery, referring to 5.1.7 th section, judging test results, judging that the batteries do not explode or fire, namely pass the test, or else, do not pass the test, and calculating the needling item passing rate of the 10 batteries.
TABLE 2
As can be seen from table 2, when the current collector prepared by the scheme of the invention is used in a lithium ion battery, the safety performance and the rate capability of the lithium ion battery can be improved.
Further, when the ratio of Rs to Rs0 satisfies: when Rs/Rs0 is more than or equal to 1.01 and less than or equal to 1.1, the lithium ion battery prepared by using the current collector has more excellent safety performance and rate capability.
When Rs is 5mΩ -1000.1mΩ, the lithium ion battery prepared by using the current collector has more excellent safety performance and rate capability.
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.