阅读说明：本技术 一种耐宽温锂电池及其制作方法 (wide-temperature-resistant lithium battery and manufacturing method thereof ) 是由 胡金星 陈立鹏 姜欢 吴志威 陈念 孙光忠 于 2019-10-28 设计创作，主要内容包括：本发明涉及锂电池技术领域,特别涉及一种耐宽温锂电池及其制作方法。本发明提供了一种耐宽温锂电池,包括正极片、负极片、隔膜、电解液和外包装膜,正极活性物质为三元掺锰酸锂,负极活性物质为人造石墨、中间相碳微球,钛酸锂中的一种；正负极导电剂为碳纳米管、SP和石墨烯,通过采用特殊的化成及老化工步工艺制成电池。正负极片包括正极涂碳铝箔集流体和负极铜箔集流体材料,正负极材料中正极活性物质80％-94％,正极导电剂3％-10％,正极粘结剂3％-10％,负极活性物质85％-96％,负极导电剂2％-7％,负极粘结剂2％-8％。实验测试结果表明,本发明中的电池在-30℃下的放电容量为室温容量的83.26％,80℃高温10天存储后,容量保持及恢复率≥90％,具备较好的温度适应性。(The invention relates to the technical field of lithium batteries, in particular to wide temperature resistant lithium batteries and a manufacturing method thereof, the invention provides wide temperature resistant lithium batteries, which comprise a positive plate, a negative plate, a diaphragm, electrolyte and an outer packaging film, wherein the positive active substance is ternary lithium manganese oxide, the negative active substance is artificial graphite, mesocarbon microbeads and kinds of lithium titanate, and the positive and negative conductive agents are carbon nanotubes, SP and graphene.)

The wide temperature resistant lithium battery is characterized by comprising a positive plate, a negative plate, a diaphragm, electrolyte and an outer packaging film, wherein the positive plate comprises a positive carbon-coated aluminum foil current collector and a positive material, the positive material comprises a positive active substance, a positive conductive agent and a positive binder, the positive active substance comprises 80-94% of the positive active substance, 3-10% of the positive conductive agent and 3-10% of the positive binder by mass, the positive active substance comprises NCM and LMO, and the mass ratio of the NCM to the LMO is 6: 4-8: 2.

2. The wide temperature lithium battery according to claim 1, wherein the NCM in the positive electrode active material is LiNi_0.33Co_0.33Mn_0.33O₂、LiNi_0.5Co_0.3Mn_0.2O₂、LiNi_0.3Co_0.35Mn_0.35O₂、LiNi_0.8Co_0.1Mn_0.1O₂、LiNi_0.4Co_0.3Mn_0.3O₂、LiNi_0.2Co_0.35Mn_0.45O₂ or more.

3. The wide temperature resistant lithium battery of claim 1, wherein the negative electrode sheet comprises a negative electrode carbon-coated aluminum foil current collector and a negative electrode material, the negative electrode material comprises a negative electrode active material, a negative electrode conductive agent and a negative electrode binder, and the negative electrode material comprises the following components in percentage by mass: 85-96% of negative electrode active material, 2-7% of negative electrode conductive agent and 2-8% of negative electrode binder.

4. The wide temperature lithium battery of claim 3, wherein the negative active material is artificial graphite, mesocarbon microbeads or lithium titanate Li₄Ti₅O₁₂The cathode binder is polyvinylidene fluoride or styrene butadiene rubber, and the cathode conductive agent is or more of superconducting carbon black SP, graphite conductive agent KS-6, carbon nano tube and carbon fiber.

5. The wide temperature lithium battery of claim 3, wherein the positive electrode conductive agent is or more of superconducting carbon black, flake graphite, carbon nanotube, carbon fiber and vapor grown fiber, and the positive electrode binder is or more of polyvinylidene fluoride, styrene butadiene rubber, organic olefine acid and carboxylic ester.

6. The wide temperature lithium battery of claim 1, wherein the electrolyte comprises a solvent, an electrolyte and an additive, and the mass ratio of the solvent to the DMC is 4-8: 1, the electrolyte comprises 15-30% of mixed solvent in the electrolyte by mass and has a concentration of 1.2-3.0mol/L, and the electrolyte comprises LiPF₆And LiFSI, LiPF₆: the LiFSI concentration ratio is 2: 1-5: 1, the additive is a composition of VC and PS, and the mass fraction of the additive composition is 0.2%-2％。

7. The wide temperature resistant lithium battery of claim 1 wherein the separator is a wet process PE separator having a thickness of 9-20um, a porosity of 40-65%, an air permeability of 100-₂O₃Ceramic diaphragm, said coating being Al₂O₃The thickness of the ceramic diaphragm is 25-30um, the porosity is 50-85%, and the air permeability is 150-200s/100 ml.

A method of making a wide temperature resistant lithium battery as claimed in claim 1 in claim 8, , said method comprising the steps of:

a) manufacturing a positive plate and a negative plate: dissolving the positive electrode material in an organic solvent, uniformly stirring, coating on a positive electrode current collector, drying at 90-120 ℃, and rolling a positive electrode plate; dispersing a negative electrode material in an organic solvent, uniformly stirring to obtain negative electrode slurry, coating the negative electrode slurry on a negative electrode current collector, drying at 90-120 ℃, and rolling to obtain a negative electrode sheet;

b) baking the pole piece: placing the pole piece into a vacuum oven for baking for 24-36h at the temperature of 100 ℃ and 120 ℃, continuously vacuumizing, and controlling the moisture content of the positive pole piece and the negative pole piece to be less than or equal to 200 ppm;

c) manufacturing an electric core: cutting the positive plate and the negative plate obtained in the step b), and manufacturing a battery cell by adopting a laminated structure or a winding structure according to the sequence of the positive plate, the diaphragm and the negative plate;

d) welding and packaging, namely respectively welding the tabs on by using positive and negative plates in the battery cell to form a positive and negative lead-out end, putting the battery cell into an aluminum-plastic packaging film, respectively leading out the positive and negative tabs, heating the tab glue to fuse the plastic of the aluminum-plastic bag and the tab glue, wherein the side of the soft package battery is in an open state, and after electrolyte is injected;

e) packaging and injecting liquid: after injecting the high-pressure electrolyte into the electric core, sealing the liquid injection port;

f) formation and aging: and (3) forming the packaged battery, aging and grading to obtain the lithium titanate battery with high multiplying power.

9. The method of claim 8, wherein the temperature of the formation in step f) is 60-90 ℃ and the pressure of the formation is 0.1-0.5MPa, the aging temperature is 60-90 ℃, the pressure of the aging is 0.1-0.5MPa, and the aging time is 30-50 h.

10. The method of claim 8, wherein the formation process in step f) includes a constant current charging and discharging process and an air extraction process, and the charging and discharging process includes the following steps:

(1) charging the battery for 5 hours at a constant current of 0.01-0.02C;

(2) charging the battery for 6h at a constant current of 0.05C;

(3) charging the battery for 3 hours at a constant current of 0.2C;

(4) exhausting air from the lower cabinet;

(5) discharging the battery for 5h at a constant current of 0.2C;

(6) the battery was constant current charged at 0.2C for 5 h.

Technical Field

The invention relates to the technical field of lithium batteries, in particular to wide-temperature-resistant lithium batteries and a manufacturing method thereof.

Background

At present, the most serious problem in the 21 st century is the energy crisis, and the replacement of non-renewable fossil energy by green energy has become a necessary development trend. Lithium ion batteries have the advantages of high energy density, long cycle life, environmental protection, etc., have occupied an important position in the digital market and the energy storage device market, and are also being gradually applied to the field of passenger vehicles, such as Hybrid Electric Vehicles (HEV), plug-in hybrid electric vehicles (PHEV), pure Electric Vehicles (EV), and other large-scale electric devices.

Since 2019, new energy passenger vehicles still have a growing trend, the mainstream market of lithium batteries is ternary lithium iron phosphate batteries, lithium iron phosphate batteries are moderate in energy density and high in safety performance and cost performance, and are the field of national key support and development, but lithium separation at low temperature and gas expansion at high temperature are bottlenecks which restrict large-scale application of the lithium batteries, so that the preparation of lithium batteries used under the wider temperature condition is which is a key way for the large-scale popularization of in the lithium battery industry.

CN109802094A discloses low-temperature lithium iron phosphate batteries and a preparation method thereof, wherein the positive plate is prepared from a positive active substance, a positive conductive agent, a positive binder and a positive solventCoating the positive electrode slurry on a positive electrode current collector to prepare the positive electrode current collector; the positive electrode active material is Ti₃SiC₂Modified carbon-coated lithium iron phosphate; the positive conductive agent is a carbon nano tube and graphene; the negative plate is prepared by coating negative slurry comprising a negative active substance, a negative conductive agent, a negative binder, a thickening agent and a negative solvent on a negative current collector; the negative active material is artificial graphite and mesocarbon microbeads; the negative electrode conductive agent is a carbon nano tube and graphene. The experimental result shows that the discharge capacity of the battery is 2488mAh at the temperature of minus 20 ℃ and is 88.13% of the capacity at room temperature; the discharge capacity at the temperature of minus 40 ℃ is 2215mAh, which is 78.46% of the discharge capacity at the room temperature, and the method is greatly helpful for improving the low-temperature performance.

The CN106229543A lithium titanate battery comprises a positive electrode, a negative electrode, an isolating membrane and electrolyte, wherein the isolating membrane is arranged between the positive electrode and the negative electrode at intervals, the positive electrode comprises a positive electrode current collector and positive electrode slurry, the negative electrode comprises a negative electrode current collector and negative electrode slurry, the electrolyte comprises an organic solvent, an additive and lithium salt, the positive electrode slurry comprises a positive electrode active substance, a conductive agent and a binder, the negative electrode slurry comprises a negative electrode active substance, a conductive agent and a binder, the positive electrode active substance is ternary nickel-cobalt-manganese NCM, and the negative electrode active substance is lithium titanate Li₄Ti₅O₁₂The conductive agent is a mixture of SP and KS-6, and the binder is polyvinylidene fluoride (PVDF); the positive electrode slurry comprises the following components in percentage by weight: NCM: SP: KS-6: PVDF 96: 1.5: 0.5: 2; the negative electrode slurry comprises the following components in percentage by weight: li₄Ti₅O₁₂: SP: KS-6: PVDF 93: 1.5: 0.5: 5, the battery also has better electrical and safety performance.

Therefore, according to the market development demand, lithium batteries with high safety performance and used under wider temperature conditions need to be prepared.

Disclosure of Invention

Aiming at the current situation of the prior art, the invention aims to provide kinds of wide-temperature-resistant lithium batteries and a preparation method thereof, the invention adopts a special material system and formation and aging processes, effectively solves the problems that the lithium batteries cannot be used at a low temperature and swell at a high temperature, and the like, and the battery core can be normally used at a temperature of-30-80 ℃.

The technical purpose of the invention is realized by the following technical scheme that kinds of wide-temperature-resistant lithium batteries comprise a positive plate, a negative plate, a diaphragm, electrolyte and an outer packaging film, wherein the positive plate comprises a positive carbon-coated aluminum foil current collector and a positive material, the positive material comprises a positive active substance, a positive conductive agent and a positive binder, the positive active substance comprises 80-94% of the positive active substance, 3-10% of the positive conductive agent and 3-10% of the positive binder by mass, the positive active substance comprises NCM and LMO, and the mass ratio of the NCM to the LMO is 6: 4-8: 2.

, the ternary NCM in the positive active material is LiNi_0.33Co_0.33Mn_0.33O₂、LiNi_0.5Co_0.3Mn_0.2O₂、LiNi_0.3Co_0.35Mn_0.35O₂、LiNi_0.8Co_0.1Mn_0.1O₂、LiNi_0.4Co_0.3Mn_0.3O₂、LiNi_0.2Co_0.35Mn_0.45O₂ or more.

, the negative plate comprises a negative carbon-coated aluminum foil current collector and a negative material, wherein the negative material comprises a negative active substance 85-96 wt%, a negative conductive agent 2-7 wt% and a negative binder 2-8 wt%.

, using artificial graphite, mesocarbon microbeads or Li lithium titanate as negative active material₄Ti₅O₁₂The cathode binder is polyvinylidene fluoride or styrene butadiene rubber, and the cathode conductive agent is or more of superconducting carbon black SP, graphite conductive agent KS-6, carbon nano tube and carbon fiber.

, the positive conductive agent is or more of superconducting carbon black, flake graphite, carbon nano tube, carbon fiber and vapor growth fiber, and the positive adhesive is or more of polyvinylidene fluoride, styrene butadiene rubber, organic olefine acid and carboxylic ester.

, the electrolyte comprises a solvent, an electrolyte and an additive, the solvent is a mixed solvent with the mass ratio of EC to DMC of 4-8: 1, the mass fraction of the electrolyte in the electrolyte is 15% -30%, the concentration of the electrolyte is 1.2-3.0mol/L, and the electrolyte comprises LiPF₆And LiFSI, LiPF₆: the LiFSI concentration ratio is 2: 1-5: 1, the additive is a composition of VC and PS, and the mass fraction of the additive composition is 0.2-2%.

, the diaphragm is a wet method PE diaphragm, the thickness of the wet method PE diaphragm is 9-20um, the porosity is 40-65%, the air permeability is 100-200s/100ml or the diaphragm is coated with Al₂O₃Ceramic diaphragm, said coating being Al₂O₃The thickness of the ceramic diaphragm is 25-30um, the porosity is 50-85%, and the air permeability is 150-200s/100 ml.

The invention also provides a manufacturing method of kinds of wide-temperature-resistant lithium batteries, which comprises the following steps:

a) preparing a positive plate and a negative plate, namely dissolving a positive material in an organic solvent, uniformly stirring, coating the mixture on a positive current collector, drying the mixture at 90-120 ℃, rolling the positive plate, dispersing a negative material in the organic solvent, uniformly stirring to obtain a negative slurry, coating the negative slurry on a negative current collector, drying the mixture at 90-120 ℃, and rolling to obtain a negative plate, wherein the positive current collector adopts a carbon-coated aluminum foil, a carbon-coated layer is SP or graphene, the thickness of the carbon-coated layer is 0.5-2um, the overall thickness of the carbon-coated aluminum foil is 12-24 mu m, the negative electrode is formed by an LTO system and of the positive current collector, and the graphite system adopts a common copper foil, and the thickness of the graphite system is 9-12 mu m;

b) baking the pole piece: placing the pole piece into a vacuum oven for baking for 24-36h at the temperature of 100 ℃ and 120 ℃, continuously vacuumizing, and controlling the moisture content of the positive pole piece and the negative pole piece to be less than or equal to 200 ppm;

c) manufacturing an electric core: cutting the positive plate and the negative plate obtained in the step b), and manufacturing a battery cell by adopting a laminated structure or a winding structure according to the sequence of the positive plate, the diaphragm and the negative plate;

d) welding and packaging, namely respectively welding the tabs on by using positive and negative plates in the battery cell to form a positive and negative lead-out end, putting the battery cell into an aluminum-plastic packaging film, respectively leading out the positive and negative tabs, heating the tab glue to fuse the plastic of the aluminum-plastic bag and the tab glue, wherein the side of the soft package battery is in an open state, and after electrolyte is injected;

e) packaging and injecting liquid: after injecting the high-pressure electrolyte into the electric core, sealing the liquid injection port;

f) formation and aging: and (3) forming the packaged battery, aging and grading to obtain the lithium titanate battery with high multiplying power.

, the positive plate after rolling in step a) has a thickness of 120-160 μm and a compacted density of 2.9-3.3g/cm3, and the negative plate after rolling has a thickness of 100-130 μm and a compacted density of 1.2-1.5g/cm 3.

, the viscosity of the anode slurry in the step a) is 4000-8000 mPa.s, the viscosity of the cathode slurry is 3000-7000 mPa.s, and the anode slurry is evenly stirred and then sieved by 100-150 meshes.

, the formation temperature in step f) is 60-90 ℃, the formation pressure is 0.1-0.5MPa, the aging temperature is 60-90 ℃, the aging pressure is 0.1-0.5MPa, and the aging time is 30-50 h.

, the formation process in step f) needs constant current charging and discharging with constant current and air extraction, the charging and discharging process comprises the following steps:

(1) charging the battery for 5 hours at a constant current of 0.01-0.02C;

(2) charging the battery for 6h at a constant current of 0.05C;

(3) charging the battery for 3 hours at a constant current of 0.2C;

(4) exhausting air from the lower cabinet;

(5) discharging the battery for 5h at a constant current of 0.2C;

(6) the battery was constant current charged at 0.2C for 5 h.

, the capacity of the negative electrode relative to the positive electrode is 10% -30%.

Wherein the final cut-off voltage during formation is 4.2-4.3V (NCM + Gr system) and 2.7-2.8V (NCM + LTO system).

The invention has the beneficial effects that:

according to the invention, the main materials of the positive electrode adopt NCM and LMO, so that the low-temperature performance of the battery cell is obviously improved, the low-temperature characteristic of the LMO is better, the LMO with a proper amount is added into the main materials, so that the application in a wide temperature range of a positive electrode material system is obviously improved, the negative electrode adopts an artificial graphite or LTO system, the negative electrode has better high-low temperature performance and safety performance by matching with the positive electrode material, a special formation and aging process is adopted, so that ester substances in the electrolyte fully generate side reactions at the negative electrode to form an SEI film of , and gas generated by the side reactions is timely discharged, so that the battery cell has better high-temperature performance, and the gas generation of the battery cell can be.

In order to ensure that the battery cell can be better used at the temperature of-30-80 ℃, the design of the diaphragm and the electrolyte is very important; the high-porosity and low-air permeability diaphragm is adopted, so that the passing rate of ions can be obviously increased, and the rate capability of the ion can be obviously improved; meanwhile, LiFSI is added into lithium salt of the electrolyte, the overall conductivity of the electrolyte can be improved, the moving speed of positive ions is increased, and VC and PS additives are added into the electrolyte, so that the stability of the multiplying power charging and discharging process of the electrolyte can be enhanced, a charging and discharging platform is wider, and the work is more stable.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a high and low temperature discharge curve of a sample;

FIG. 2 is a graph of sample 32Ah cycling.

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments, it is to be understood that the described embodiments are only a partial embodiment of the present invention, rather than a complete embodiment.

In the invention, EMC is methyl ethyl carbonate, DEC is diethyl carbonate, EC is ethylene carbonate, NMP is N-methyl pyrrolidone, PVDF is polyvinylidene fluoride, CMC is sodium carboxymethylcellulose, LMO is lithium manganate, and NCM is ternary nickel cobalt lithium manganate.

kinds of wide temperature resistant lithium battery and its manufacturing method, the following embodiments are specified: