阅读说明：本技术 高能量密度长寿命的快充锂离子电池及其制备方法 (Fast-charging lithium ion battery with high energy density and long service life and preparation method thereof ) 是由 黄碧英 黄耀泽 唐天文 萨多威.R.唐纳德 于 2020-05-13 设计创作，主要内容包括：本发明公开了一种高能量密度长寿命的快充锂离子电池及其制备方法,所述低温为-20℃；所述快速充电的倍率分别为1C和2C,所述快速放电的倍率分别为1C和3C；所述锂离子电池主要由正极片、负极片、陶瓷隔膜、电解液、电池壳这五部份组成,经“正极片-陶瓷隔膜-负极片-陶瓷隔膜”组合并层叠后放入电池壳、注入电解液、开口化成、封口、分容制成；本发明通过对镍钴铝酸锂、硅碳复合材料、大分子增塑剂、纳米微孔覆碳铝网、纳米微孔铜网、高温绝缘胶带、高分子胶、陶瓷隔膜、电解液、电池壳等优选材料以及优选的工艺技术,充分说明了本发明的有益效果。非常适合3C、动力和储能等领域的应用。(The invention discloses a fast-charging lithium ion battery with high energy density and long service life and a preparation method thereof, wherein the low temperature is-20 ℃; the multiplying power of the quick charge is 1C and 2C respectively, and the multiplying power of the quick discharge is 1C and 3C respectively; the lithium ion battery mainly comprises a positive plate, a negative plate, a ceramic diaphragm, electrolyte and a battery case, and is prepared by combining and laminating the positive plate, the ceramic diaphragm, the negative plate and the ceramic diaphragm, then placing the obtained product into the battery case, injecting the electrolyte, opening the battery case into the battery case, forming the battery case, sealing the battery case and grading the battery case; the beneficial effects of the invention are fully demonstrated by the optimized materials and the optimized process technology of nickel cobalt lithium aluminate, silicon carbon composite material, macromolecule plasticizer, nanometer micropore carbon-coated aluminum net, nanometer micropore copper net, high temperature insulating tape, macromolecule glue, ceramic diaphragm, electrolyte, battery shell and the like. Is very suitable for the application in the fields of 3C, power, energy storage and the like.)

1. The quick-charging lithium ion battery with high energy density and long service life is characterized in that the low temperature is-20 ℃; the multiplying power of the quick charge is 1C and 2C respectively, and the multiplying power of the quick discharge is 1C and 3C respectively; the lithium ion battery consists of a positive plate, a negative plate, a ceramic diaphragm, electrolyte and a battery shell, and is prepared by combining and winding or laminating the positive plate, the ceramic diaphragm, the negative plate and the ceramic diaphragm, then placing the battery shell into the battery shell, injecting the electrolyte, opening the battery shell to form, sealing and grading; the method is characterized in that: the positive electrode material of the positive plate is nickel-cobalt lithium aluminate which is formed by primary nano particles with the particle size of 500-700 nm and secondary micro particles with the particle size of 10-12 um, and the positive electrode material is prepared by a solid-phase melting method, wherein the weight ratio of nickel: cobalt: the aluminum ratio is 85: 10: 5, the gram specific capacity is 240mAh/g, and the energy density is more than 230 wh/kg; the negative electrode material of the negative electrode plate is a silicon-carbon composite material which is formed by primary nano particles with the particle size of 500-700 nm and secondary micro particles with the particle size of 10-12 um, and is prepared by an organic solvent liquid phase dispersion coating method and a solid phase melting carbonization method, wherein the silicon: the carbon ratio is 22: 78 g, specific capacity of 600mAh/g, and energy density of more than 450 wh/kg; the battery shell is a square aluminum shell or an aluminum plastic shell.

2. The method for preparing a high energy density long life fast charging lithium ion battery of claim 1, characterized in that it comprises the following steps:

1) positive plate: preparing a mixed solution of 230.46 kg of lithium nickel cobalt aluminate, 0.47 kg of superconducting carbon black conductive agent, 24.56 kg of carbon nano tube conductive agent, 60 kg of macromolecular plasticizer and 3.06 kg of polyvinylidene fluoride adhesive into positive electrode slurry, uniformly coating the positive electrode slurry on the front surface and the back surface of the nano micropore carbon-coated aluminum net to form a positive electrode coating, and reserving 20mm blanks on the edges of the positive electrode coating in four directions and the edges of the nano micropore carbon-coated aluminum net; putting the positive plate into an oven, and drying for 4 hours in a vacuum environment at the temperature of 80 ℃ to remove the N-methylpyrrolidone solvent to obtain a positive plate; rolling the positive plate to a compact state by using a calender, and extracting the macromolecular plasticizer in the positive plate by using IPA (isopropyl alcohol); the blank of the opposite side of the positive plate reserved with the positive electrode tab is shallow soaked in polymer adhesive to be wrapped by the polymer adhesive, then the positive plate is placed in an oven and dried for 4 hours in a vacuum environment at 110 ℃ to remove moisture, and the positive plate with high porosity and the surface density of 275g/m2 and the compacted density of 3.8g/cm3 is obtained;

2) a negative plate, namely preparing a negative slurry from a mixed solution of 106.50 silicon-carbon composite materials, 1.11 kg of superconducting carbon black conductive agent, 60 kg of macromolecular plasticizer, 4.59 kg of styrene-butadiene rubber binder and 1.45 kg of sodium carboxymethylcellulose binder, uniformly coating the negative slurry on the front surface and the back surface of a nano microporous copper mesh to form a negative coating, and reserving 15mm blanks on the edges of the four directions of the plane of the negative coating and the edges of the nano microporous copper mesh; putting the anode sheet into an oven, and drying for 4 hours in a vacuum environment at 80 ℃ to remove the hydrosolvent to obtain a cathode sheet; rolling the negative plate to a compact state by using a calender, and extracting the macromolecular plasticizer in the negative plate by using IPA (isopropyl alcohol); shallow-soaking the blank of the opposite side of the negative pole plate, which is reserved with the negative pole tab, in polymer glue to wrap the negative pole plate, then putting the negative pole plate into an oven, and drying for 4 hours in a vacuum environment at 110 ℃ to remove moisture, so as to obtain the negative pole plate with high porosity, the surface density of which is 130g/m2 and the compacted density of which is 1.4g/cm 3;

3) a ceramic diaphragm: coating the front and back surfaces of the diaphragm with nano alumina coatings, and removing the solvent in the alumina coatings by using a vacuum baking oven to obtain the nano microporous ceramic diaphragm with high porosity and high wettability in a low-temperature environment;

4) electrolyte solution: mixing a solvent with relatively low viscosity and low melting point, a solvent with relatively high viscosity and/or high melting point and a lithium salt-solvent combination of high-conductivity ions in a low-temperature environment to obtain a low-temperature electrolyte;

5) dry cell: the positive plate-ceramic diaphragm-negative plate-ceramic diaphragm are sequentially laminated in the repeated sequence, and in the laminating process: the high-temperature insulating adhesive tape for the positive plate wraps the blank of 20mm reserved on the two side edges of the positive electrode lug by a nano micropore carbon-coated aluminum net in a U shape, the part of the current collector nano micropore carbon-coated aluminum net piece reserved slightly longer than the positive coating is stacked and gathered together to form a multiple positive electrode lug, and the multiple positive electrode lug and the planar metal sheet current collector are welded together to form a positive electrode full lug; the negative plate is wrapped with a blank of 15mm reserved on two side edges of a negative pole lug by a high-temperature insulating adhesive tape in a U shape, the part of a current collector nanometer micropore copper net piece reserved slightly longer than a negative coating is stacked to be gathered together to form a multiple negative pole lug, and the multiple negative pole lug and a planar metal sheet current collector are welded together to form a negative pole full lug;

6) assembling the battery: compacting the dry cell to enable the contact of the positive plate, the negative plate and the ceramic diaphragm to be more compact, then placing the dry cell into a cell shell, respectively connecting the positive full tab and the negative full tab with external current collectors, and injecting electrolyte to manufacture the square cell according to the conventional manufacturing process of the square cell; finally, the fast-charging lithium ion battery with high energy density and long service life is obtained.

3. The method according to claim 2, wherein the macromolecular plasticizer is one or a mixture of two or more of DBP, PTP, DOP and DIDP.

4. The preparation method of claim 2, wherein the nano microporous carbon-coated aluminum mesh is a mesh of a porous aluminum material with the front and back sides coated with Super-P, PAA, and the thickness is 12 μm.

5. The method according to claim 2, wherein the nanoporous copper mesh is a porous copper mesh having a thickness of 8 um.

6. The preparation method of claim 2, wherein the high-temperature insulating tape comprises a two-layer structure of a substrate and a glue layer, the substrate is one or a mixture of more than two of polyimide, polysulfone, polyphenylene sulfide and polyether ketone, and the glue layer is silica gel; the whole thickness of high temperature insulating tape is 10 ~ 60um, and its thermal stability is greater than 200 ℃.

7. The method according to claim 2, wherein the polymer adhesive is one or a mixture of PVDF and PAN.

8. The preparation method of claim 2, wherein the diaphragm is prepared by an electrospinning method, has a thickness of 6-40 um, and has the characteristics of high mechanical strength and high thermal stability; the area of the nano aluminum oxide coating on the ceramic diaphragm is larger than the areas of the anode coating on the anode plate and the cathode coating on the cathode plate.

9. The preparation method according to claim 2, wherein the "relatively low-viscosity and low-melting point solvent" is one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl butyrate and ethyl butyrate; the "relatively high-viscosity and/or high-melting-point solvent" is formed by mixing one or more than two solvents of ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, vinylene carbonate, propyl butyrate, gamma-butyrolactone and valerolactone; the lithium salt-solvent combination is a solution consisting of high-purity lithium salt and multi-element carbonate, wherein the lithium salt is as follows: one or more of LiPF6, LiBF4, LiBOB and LiBC2O4F2, and the concentration of lithium salt is 0.7-2M.

Technical Field

The invention relates to the technical field of 3C, power and energy storage lithium ion secondary batteries, in particular to a preparation method of a fast charging lithium ion battery with high energy density and long service life.

Background

In the modern society, along with the rapid development of economy, energy crisis and environmental problems are increasingly aggravated. Lithium ion batteries have been widely used in the fields of 3C, power and energy storage, because of their advantages of high energy density, high power density, long cycle life, no memory effect, low self-discharge rate, wide working temperature range, safety, reliability, and environmental friendliness. Meanwhile, the method has good application prospect in special fields of pure electric vehicles, hybrid electric vehicles, military industry and the like.

However, in recent years, the demand for energy density of batteries has been rapidly increasing in various fields, and there is a strong demand for development of a lithium ion battery having a high energy density, which is safe and has a rapid charge/discharge performance in a low-temperature environment. At present, the positive electrode materials used by commercial lithium ion batteries are mainly lithium iron phosphate, lithium cobaltate, lithium manganate and nickel cobalt lithium manganate, and the negative electrode materials used by commercial lithium ion batteries are mainly mesocarbon microbeads and artificial graphite. The lithium ion battery prepared by matching the anode material and the cathode material is difficult to exert higher energy density under the conditions of low temperature and rapid charge and discharge, the energy density of the conventional lithium iron/graphite battery is 130-140wh/kg, the energy density of the lithium cobaltate/graphite battery is 135-150wh/kg, the energy density of the lithium manganate/graphite battery is 100-120wh/kg, and the energy density of the nickel cobalt lithium manganate/graphite battery is 200-220wh/kg, so the promotion space of the energy density of the lithium ion battery is quite limited.

Under such a background, it is necessary to develop a battery, which not only has a fast charge and discharge performance in a low temperature environment, but also has a high safety and stability performance and a long cycle life, and has a higher energy density to meet higher requirements in various application fields.

Disclosure of Invention

The invention aims to make up for the defects of the prior art and provides a fast-charging lithium ion battery with high energy density and long service life and a preparation method thereof.

The technical scheme is as follows:

the quick-charging lithium ion battery with high energy density and long service life is characterized in that the low temperature is-20 ℃; the multiplying power of the quick charge is 1C and 2C respectively, and the multiplying power of the quick discharge is 1C and 3C respectively; the lithium ion battery consists of a positive plate, a negative plate, a ceramic diaphragm, electrolyte and a battery shell, and is prepared by combining and winding or laminating the positive plate, the ceramic diaphragm, the negative plate and the ceramic diaphragm, then placing the battery shell into the battery shell, injecting the electrolyte, opening the battery shell to form, sealing and grading; the positive electrode material of the positive plate is nickel-cobalt lithium aluminate which is formed by primary nano particles with the particle size of 500-700 nm and secondary micro particles with the particle size of 10-12 um, and the positive electrode material is prepared by a solid-phase melting method, wherein the weight ratio of nickel: cobalt: the aluminum ratio is 85: 10: 5, the gram specific capacity is 240mAh/g, and the energy density is more than 230 wh/kg; the negative electrode material of the negative electrode plate is a silicon-carbon composite material which is formed by primary nano particles with the particle size of 500-700 nm and secondary micro particles with the particle size of 10-12 um, and is prepared by an organic solvent liquid phase dispersion coating method and a solid phase melting carbonization method, wherein the silicon: the carbon ratio is 22: 78 g, specific capacity of 600mAh/g, and energy density of more than 450 wh/kg; the battery shell is a square aluminum shell or an aluminum plastic shell.

The preparation method of the fast charging lithium ion battery with high energy density and long service life comprises the following steps:

positive plate: preparing a mixed solution of 230.46 kg of lithium nickel cobalt aluminate, 0.47 kg of superconducting carbon black conductive agent, 24.56 kg of carbon nano tube conductive agent, 60 kg of macromolecular plasticizer and 3.06 kg of polyvinylidene fluoride adhesive into positive electrode slurry, uniformly coating the positive electrode slurry on the front surface and the back surface of the nano micropore carbon-coated aluminum net to form a positive electrode coating, and reserving 20mm blanks on the edges of the positive electrode coating in four directions and the edges of the nano micropore carbon-coated aluminum net; putting the positive plate into an oven, and drying for 4 hours in a vacuum environment at the temperature of 80 ℃ to remove the N-methylpyrrolidone solvent to obtain a positive plate; rolling the positive plate to a compact state by using a calender, and extracting the macromolecular plasticizer in the positive plate by using IPA (isopropyl alcohol); and (3) slightly soaking the blank of the opposite side of the anode plate, which is reserved with the anode tab, in polymer glue to wrap the anode plate, then putting the anode plate into an oven, and drying for 4 hours in a vacuum environment at 110 ℃ to remove water, so as to obtain the anode plate with high porosity, wherein the surface density of the anode plate is 275g/m2, and the compacted density of the anode plate is 3.8g/cm 3.

2) A negative plate, namely preparing a negative slurry from a mixed solution of 106.50 silicon-carbon composite materials, 1.11 kg of superconducting carbon black conductive agent, 60 kg of macromolecular plasticizer, 4.59 kg of styrene-butadiene rubber binder and 1.45 kg of sodium carboxymethylcellulose binder, uniformly coating the negative slurry on the front surface and the back surface of a nano microporous copper mesh to form a negative coating, and reserving 15mm blanks on the edges of the four directions of the plane of the negative coating and the edges of the nano microporous copper mesh; putting the anode sheet into an oven, and drying for 4 hours in a vacuum environment at 80 ℃ to remove the hydrosolvent to obtain a cathode sheet; rolling the negative plate to a compact state by using a calender, and extracting the macromolecular plasticizer in the negative plate by using IPA (isopropyl alcohol); and shallow soaking the blank of the opposite side of the negative electrode plate, which is reserved with the negative electrode tab, in polymer adhesive to wrap the negative electrode plate, then putting the negative electrode plate into an oven, and drying for 4 hours in a vacuum environment at 110 ℃ to remove moisture, thereby obtaining the negative electrode plate with high porosity, the surface density of which is 130g/m2 and the compacted density of which is 1.4g/cm 3.

3) A ceramic diaphragm: coating the front and back surfaces of the diaphragm with nano alumina coatings, and removing the solvent in the alumina coatings by using a vacuum baking oven to obtain the nano microporous ceramic diaphragm with high porosity and high wettability in a low-temperature environment; by selecting a porous ceramic diaphragm with high porosity and high wettability in a low-temperature environment and forming a nano alumina ceramic coating on the surface of the diaphragm, the firewall effect is exerted, and the melting point (PP melting point 165 ℃ and PE melting point 92 ℃) of the diaphragm is effectively improved; the hardness of the surface of the diaphragm is enhanced, and the risk that hard-strength active substances and burrs penetrate through the diaphragm is effectively reduced; the adhesive property of the nano alumina ceramic coating and the active material coating is effectively improved, and the affinity property of the nano alumina ceramic coating and the electrolyte is improved. The high porosity of the ceramic diaphragm of more than 45 percent can enable more Li + to migrate and diffuse between the positive/negative plates at a higher speed in unit time; the high wettability enables the electrolyte to be better adhered and infiltrated into the diaphragm, not only fully exerts the carrier effect of the electrolyte on Li +, but also optimizes and improves the transmission rate of migration and diffusion of Li + and electrons in the electrode and between the electrode and the electrolyte interface, improves the low-temperature ionic conductivity of the electrolyte, and solves the problem of high-rate rapid charge and discharge of the lithium ion battery applied in a low-temperature environment in many aspects.

4) Electrolyte solution: mixing a solvent with relatively low viscosity and low melting point, a solvent with relatively high viscosity and/or high melting point and a lithium salt-solvent combination of high-conductivity ions in a low-temperature environment to obtain a low-temperature electrolyte; preferably, a portion of the relatively higher viscosity and/or higher melting point solvent is replaced in a suitable amount by a "relatively lower viscosity and lower melting point solvent", which is in a greater amount than the "relatively higher viscosity and/or higher melting point solvent"; the viscosity of the electrolyte can be effectively reduced, and the fluidity of the electrolyte in the battery is improved; the inertness of active substances and Li & lt + & gt in the electrolyte in an extremely low temperature environment is eliminated, and the flexibility of Li & lt + & gt migration is improved; the low-temperature ionic conductivity and the electron transmission rate of the battery are optimized and improved; and meanwhile, the risk of embrittlement and shedding of the anode material caused by carbonization is reduced.

5) Dry cell: the positive plate-ceramic diaphragm-negative plate-ceramic diaphragm are sequentially laminated in the repeated sequence, and in the laminating process: the high-temperature insulating adhesive tape for the positive plate wraps the blank of 20mm reserved on the two side edges of the positive electrode lug by a nano micropore carbon-coated aluminum net in a U shape, the part of the current collector nano micropore carbon-coated aluminum net piece reserved slightly longer than the positive coating is stacked and gathered together to form a multiple positive electrode lug, and the multiple positive electrode lug and the planar metal sheet current collector are welded together to form a positive electrode full lug; the negative plate is wrapped with a blank of 15mm reserved on two side edges of a negative pole lug by a high-temperature insulating adhesive tape in a U shape, the part of a current collector nanometer micropore copper net piece reserved slightly longer than a negative coating is stacked to be gathered together to form a multiple negative pole lug, and the multiple negative pole lug and a planar metal sheet current collector are welded together to form a negative pole full lug; the polymer adhesive and the high-temperature insulating adhesive tape are selected to wrap the edge of the coating of the positive/negative pole piece, so that the risk that burrs remained when the pole piece is cut penetrate through the diaphragm is avoided, and the internal short circuit of the battery is prevented; compared with the conventional lithium ion battery production technology, the invention reduces the conventionally used pole piece cutting and slitting process and the process of welding the single metal pole lug to the current collector mesh, and has no redundant cutting and slitting steps except that the positive/negative pole piece and the diaphragm need to be slightly cut at the tail end, thereby greatly reducing the workload of cutting and slitting, greatly reducing the generation of powder falling and burrs of hard-strength active substance particles of the pole piece and further improving the safety performance of the battery; the parts of the metal mesh sheets of the reserved current collector are gathered together to form multiple tabs and are welded with the planar metal sheet current collector to form a full tab, so that the internal resistance and temperature rise of the battery in high-rate rapid charge and discharge in a low-temperature environment are reduced, and the high-current charge and discharge performance, the safety and stability performance and the cycle life of the battery are effectively improved. The process is simple and convenient, and is very suitable for the application in the fields of 3C, power, energy storage and the like.

6) Assembling the battery: compacting the dry cell to enable the contact of the positive plate, the negative plate and the ceramic diaphragm to be more compact, then placing the dry cell into a cell shell, respectively connecting the positive full tab and the negative full tab with external current collectors, and injecting electrolyte to manufacture the square cell according to the conventional manufacturing process of the square cell; finally, the fast-charging lithium ion battery with high energy density and long service life is obtained.

The macromolecular plasticizer is one or a mixture of more than two of DBP, PTP, DOP and DIDP.

The nano microporous carbon-coated aluminum net is a porous aluminum net sheet with the front surface and the back surface coated with Super-P, PAA, and the thickness of the nano microporous carbon-coated aluminum net sheet is 12 mu m; the nanometer micropore copper net is a porous copper net sheet, and the thickness is 8 um.

The high-temperature insulating tape comprises a substrate and a glue layer, wherein the substrate is one or a mixture of more than two of polyimide, polysulfone, polyphenylene sulfide and polyether ketone, and the glue layer is silica gel; the whole thickness of high temperature insulating tape is 10 ~ 60um, and its thermal stability is greater than 200 ℃.

The polymer adhesive is one or a mixture of PVDF and PAN.

The manufacturing method of the diaphragm is an electrostatic spinning method, the thickness of the diaphragm is 6-40 um, and the diaphragm has the characteristics of high mechanical strength and strong thermal stability; the area of the nano aluminum oxide coating on the ceramic diaphragm is larger than the areas of the anode coating on the anode plate and the cathode coating on the cathode plate.

The "relatively low viscosity and low melting point solvent" is: one or more than two solvents of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl butyrate and ethyl butyrate are mixed to form the compound; the "relatively high-viscosity and/or high-melting-point solvent" is formed by mixing one or more than two solvents of ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, vinylene carbonate, propyl butyrate, gamma-butyrolactone and valerolactone; the lithium salt-solvent combination is a solution consisting of high-purity lithium salt and multi-element carbonate, wherein the lithium salt is as follows: one or more of LiPF6, LiBF4, LiBOB and LiBC2O4F2, and the concentration of lithium salt is 0.7-2M.

The invention has the following beneficial effects:

by selecting the nickel cobalt lithium aluminate doped with the aluminum element as the anode material, the safety and stability performance and the cycle life of the lithium battery in the charging and discharging process can be improved more effectively; by selecting the soft carbon silicon-carbon composite material as the negative electrode material, the risks of brittle fracture and falling caused by carbonization of the negative electrode material after the negative electrode material is compatible with a low-viscosity low-melting-point solvent can be effectively reduced; the weight energy density of the nano-grade nickel-cobalt lithium aluminate is more than 230wh/kg, the weight energy density of the nano-grade silicon-carbon composite material is more than 450wh/kg, and the weight energy density of the lithium ion battery prepared by matching the nano-grade nickel-cobalt lithium aluminate and the nano-grade silicon-carbon composite material is more than 230wh/kg, which is obviously superior to that of a commercial lithium ion battery; meanwhile, the nickel-cobalt lithium aluminate nanoparticles with the primary particle size of 500-700 nm form secondary micrometer particles with the secondary particle size of 10-12 um, and the silicon-carbon composite material selects nanoparticles with the primary particle size of 50-100 nm to form secondary micrometer particles with the secondary particle size of 13-17 um, so that the migration distance of Li & lt + & gt can be effectively reduced by the primary nanoparticles, the migration speed of Li & lt + & gt in the charging and discharging process of the battery is increased, the compaction density of the positive/negative electrode plate can be effectively increased by the secondary micrometer particles, and the energy density of the battery is further increased.

2) By using the square aluminum shell or the aluminum-plastic shell as the battery shell, the effective space of the battery PACK can be more fully utilized when the battery PACK is assembled, and the volume energy density of the battery is further improved.

3) By selecting the nano microporous carbon-coated aluminum net to replace the traditional aluminum foil and the nano microporous copper net to replace the traditional copper foil, the positive/negative plate formed by the method has higher porosity and can more effectively improve the compaction density and the surface density of the positive/negative plate; meanwhile, the mesh can connect the active substances on the front and back surfaces of the anode/cathode plate into a whole, can eliminate the partition wall effect of the traditional foil, more effectively increases the contact area of the active substances on the front and back surfaces of the anode/cathode plate, reduces the migration distance of Li +, reduces the migration resistance of Li +, and improves the migration speed of Li +.

Drawings

Fig. 1 is a graph of 1C and 2C charging curves of a lithium ion battery in a low temperature environment of-20 ℃.

Fig. 2 is a graph of 1C and 3C discharge curves of a lithium ion battery in a low temperature environment of-20 ℃.

FIG. 3 is a graph of the cycle life of a lithium ion battery at-20 ℃ in a low temperature environment, 2C charge/3C discharge.

Detailed Description

A method for manufacturing a fast-charging lithium ion battery with high energy density and long service life comprises the following steps:

step 1, preparation of a positive active material solvent: 3.06 kg of polyvinylidene fluoride (PVDF) binder (900) was added to 58.70 kg of N-methylpyrrolidone (NMP) solvent and dissolved by stirring thoroughly to form a viscous liquid.

Step 2, manufacturing a positive plate: 230.46 kg of lithium Nickel Cobalt Aluminate (NCA), 0.47 kg of superconducting carbon black conductive agent (SP), 24.56 kg of carbon nanotube conductive agent (CNTS) and 60 kg of macromolecular plasticizer (DBP) are added into the viscous liquid obtained in the step 1 to be fully mixed, and are uniformly stirred by a stirrer to obtain viscous positive electrode slurry. Uniformly coating the positive electrode slurry on the front surface and the back surface of a 12-micrometer-thickness nano micropore carbon-coated aluminum net, and reserving 20mm blanks on the edges of the four directions of the positive electrode coating plane and the edges of the nano micropore carbon-coated aluminum net in the coating process; putting the positive plate into an oven, and drying for 4 hours in a vacuum environment at the temperature of 80 ℃ to remove the N-methylpyrrolidone solvent to obtain a positive plate; rolling the positive plate to a compact state by using a calender, and extracting the macromolecular plasticizer in the positive plate by using IPA (isopropyl alcohol); and (3) slightly soaking the blank of the opposite side of the anode plate, which is reserved with the anode tab, in polymer glue to wrap the anode plate, then putting the anode plate into an oven, and drying for 4 hours in a vacuum environment at 110 ℃ to remove water, so as to obtain the anode plate with high porosity, wherein the surface density of the anode plate is 275g/m2, and the compacted density of the anode plate is 3.8g/cm 3.

Step 3, preparing a negative active material solvent: 4.59 kg of styrene-butadiene rubber binder (SBR) and 1.45 kg of sodium carboxymethylcellulose binder (CMC) were added to 58.70 kg of a pure water solvent and sufficiently stirred and dissolved to form a viscous liquid.

And 4, manufacturing the negative plate: 106.50 silicon carbon composite material (SiC), 1.11 kg of superconducting carbon black conductive agent (SP) and 60 kg of macromolecular plasticizer (DBP) are added into the viscous liquid obtained in the step 3 to be fully mixed, and are uniformly stirred by a stirrer to obtain viscous negative electrode slurry. Uniformly coating the negative electrode slurry on the front surface and the back surface of a nano-microporous copper net with the thickness of 8 mu m, and reserving 15mm blanks on the edges of the four directions of the negative electrode coating plane and the edges of the nano-microporous copper net in the coating process; putting the anode sheet into an oven, and drying for 4 hours in a vacuum environment at 80 ℃ to remove the hydrosolvent to obtain a cathode sheet; rolling the negative plate to a compact state by using a calender, and extracting the macromolecular plasticizer in the negative plate by using IPA (isopropyl alcohol); and shallow soaking the blank of the opposite side of the negative electrode plate, which is reserved with the negative electrode tab, in polymer adhesive to wrap the negative electrode plate, then putting the negative electrode plate into an oven, and drying for 4 hours in a vacuum environment at 110 ℃ to remove moisture, thereby obtaining the negative electrode plate with high porosity, the surface density of which is 130g/m2 and the compacted density of which is 1.4g/cm 3.

Step 5, manufacturing the ceramic diaphragm: and coating the front surface and the back surface of the diaphragm with a nano alumina coating, and removing the solvent by virtue of vacuum drying of an oven to obtain the porous ceramic diaphragm with high porosity and high wettability.

Step 6, preparing electrolyte: the low-temperature electrolyte is obtained by mixing a proper amount of a low-viscosity and low-melting-point solvent which replaces a part of a relatively high-viscosity and/or high-melting-point solvent with a lithium salt-solvent combination of high-conductivity ions in a low-temperature environment.

Step 7, manufacturing the dry electric core: sequentially laminating the positive plate, the negative plate and the ceramic diaphragm in the steps 2, 4 and 5 according to the repeated sequence of the positive plate-ceramic diaphragm-negative plate-ceramic diaphragm, and in the laminating process: firstly, a positive plate is wrapped with a nano micropore carbon-coated aluminum net in a U shape by a high-temperature insulating adhesive tape, a blank of 20mm is reserved on two side edges of a positive pole lug, the part of a current collector nano micropore carbon-coated aluminum net piece reserved slightly longer than a positive coating is stacked and gathered together to form a multiple positive pole lug, and the multiple positive pole lug and a planar metal sheet current collector are welded together to form a positive pole full lug; secondly, the negative pole piece is wrapped with a U-shaped blank of 15mm reserved on two side edges of the negative pole lug by a high-temperature insulating adhesive tape, the part of the current collector nanometer micropore copper net piece reserved slightly longer than the negative pole coating is stacked to be gathered together to form a multiple negative pole lug, and the multiple negative pole lug is welded with the planar metal sheet current collector to form a negative pole full lug. .

And 8, assembling the battery: applying a certain pressure on a dry battery core at a certain temperature to enable the positive plate, the negative plate and the ceramic diaphragm to be in more compact contact, then placing the dry battery core into a battery shell, respectively connecting the full lugs of the positive/negative electrodes with external current collectors, injecting electrolyte, and then manufacturing according to the conventional manufacturing process of a square battery; finally, the fast-charging lithium ion battery with high energy density and long service life is obtained.

The above description is only intended to represent one embodiment of the present invention, and the description is in detail, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, the military could also make several modifications and improvements to the fast charging and discharging and safe low-temperature lithium ion battery without departing from the concept of the present invention, and these modifications and improvements are all within the protection scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.