CN110649266A

CN110649266A - Lithium ion battery based on carbon nanotube film and preparation method thereof

Info

Publication number: CN110649266A
Application number: CN201910849246.9A
Authority: CN
Inventors: 李赫然; 李青; 王清辉; 史晨星; 杨鹏; 李华锋; 杜冬冬; 吴子平
Original assignee: Beijing Xu Jiang Technology Co Ltd
Current assignee: Beijing Xu Jiang Technology Co Ltd
Priority date: 2019-09-09
Filing date: 2019-09-09
Publication date: 2020-01-03

Abstract

The present disclosure relates to a lithium ion battery based on a carbon nanotube film and a preparation method thereof, the lithium ion battery comprises a positive plate, a negative plate, a diaphragm and an electrolyte, wherein the diaphragm separates the positive plate from the negative plate, and the electrolyte is filled among the positive plate, the negative plate and the diaphragm; the positive plate comprises a positive current collector and a positive active material coated on the surface of the positive current collector, the negative plate comprises a negative current collector and a negative active material coated on the surface of the negative current collector, the positive current collector and the negative current collector are respectively carbon nanotube macroscopic films, each positive current collector is provided with at least two positive lugs, and each negative current collector is provided with at least two negative lugs. The internal resistance of the lithium ion battery provided by the disclosure is obviously reduced, so that the output power and the safety performance of the battery are improved.

Description

Lithium ion battery based on carbon nanotube film and preparation method thereof

Technical Field

The disclosure relates to the technical field of batteries, in particular to a lithium ion battery based on a carbon nanotube film and a preparation method thereof.

Background

With the rapid development of high and new technologies, the related technologies of mobile portable electronic devices are also changing day by day, and the pursuit of electronic products by people tends to be personalized, so that the performance of the electronic products is emphasized, whether the appearance of the electronic products has characteristics is gradually concerned, and foldable electronic devices are gradually emerging, and under the trend, the demand for foldable lithium ion batteries is generated. The mature lithium ion battery in the market at present is bulky and can not be bent and folded, in order to make the battery flexible and realize the operations including bending and folding, many people try to use a carbon nanotube film as a current collector to bear positive and negative electrode active materials as a battery pole piece, the lithium ion battery assembled by the pole piece has excellent bendable and foldable effects, but the traditional carbon nanotube film current collector is mainly prepared by a high-temperature vapor deposition method, in the preparation process, a large amount of catalyst is needed as a growth substrate, the introduction of the catalyst causes the grown carbon nanotube unit to contain a large amount of impurities, the impurities seriously affect the conductivity of the carbon nanotube film, finally cause the internal resistance of the assembled flexible battery to be larger, the battery self-heating phenomenon can be accompanied in the heavy current charging and discharging process, so that thermal runaway is easily caused and potential safety hazards are caused.

Disclosure of Invention

The lithium ion battery based on the carbon nanotube film and the preparation method thereof are low in internal resistance and obviously improved in charging efficiency.

In order to achieve the above object, the present disclosure provides a lithium ion battery based on a carbon nanotube film, the lithium ion battery including a positive plate, a negative plate, a separator and an electrolyte, the separator separates the positive plate from the negative plate, and the electrolyte is filled between the positive plate, the negative plate and the separator; the positive plate comprises a positive current collector and a positive active material coated on the surface of the positive current collector, the negative plate comprises a negative current collector and a negative active material coated on the surface of the negative current collector, the positive current collector and the negative current collector are respectively carbon nanotube macroscopic films, each positive current collector is provided with at least two positive lugs, and each negative current collector is provided with at least two negative lugs.

Optionally, each positive current collector is provided with 3-10 positive tabs, and each negative current collector is provided with 3-10 negative tabs.

Optionally, the electrolyte in the plate pack is in a liquid state, a semi-solid state, a quasi-solid state, or a full solid state.

Optionally, the positive active material includes one or more selected from lithium cobaltate, lithium manganate, lithium nickelate, nickel cobalt manganese, nickel manganese and lithium iron phosphate, and the negative active material includes one or more selected from graphite, coke, sulfur, silicon, lithium titanate, silicon carbon and graphene.

Optionally, the carbon nanotube macroscopic film has a tensile strength of 10Pa to 10000MPa, a thickness of 1 μm to 1000 μm, an electrical conductivity of 0.1S/m to 100,000S/m, and an areal density of more than 0.1mg/cm²To 100mg/cm²。

The present disclosure also provides a preparation method of the foregoing lithium ion battery, including:

preparing a positive plate and a negative plate; the positive plate comprises a positive current collector and a positive active material coated on the surface of the positive current collector, the negative plate comprises a negative current collector and a negative active material coated on the surface of the negative current collector, and the positive current collector and the negative current collector are carbon nanotube macroscopic films respectively; each positive current collector is provided with at least two positive lugs, and each negative current collector is provided with at least two negative lugs; the positive current collector and the negative current collector are carbon nano tube macroscopic films;

sequentially stacking and assembling a negative plate, a diaphragm, a positive plate, a diaphragm and a negative plate in sequence to form a battery cell and welding a tab, wherein the positive plate and the negative plate are separated by the diaphragm, and the negative plate is laminated on two surfaces of the outermost layer of the battery cell, wherein the tab is welded in a fillet welding manner to weld a carbon nanotube film and a metal tab with tab glue;

vacuum drying for 24h, and injecting the electrolyte into a glove box with moisture content less than 20 ppm.

Optionally, the preparation method of the positive plate comprises the following steps:

reserving the position of a positive lug of a positive current collector for subsequent cutting, and then coating positive slurry on the surface of the positive current collector, wherein the coating thickness of the positive slurry is 1-500 mu m, and the surface density is 1mg/cm²To 30mg/cm²(ii) a The positive electrode slurry contains a positive electrode active material, a first binder, a first conductive agent and a first solvent, wherein the content of the binder is 1-6 wt% and the content of the conductive agent is 1-10 wt% based on the total weight of the positive electrode active material, the binder and the conductive agent; taking the weight of the positive electrode slurry as a reference, the solid content of the positive electrode slurry is 40-80 wt%; the binder is polyvinylidene fluoride, the conductive agent is one or more selected from carbon black, carbon nanotubes and graphene, and the solvent is N-methylpyrrolidone;

drying and rolling the coated positive current collector; wherein the drying temperature is 100-220 ℃, and the drying time is 0.1-10 h; the rolling pressure is 0.01-10T.

Optionally, the preparation method of the negative electrode plate comprises the following steps:

shielding a negative electrode lug of a negative electrode current collector, and coating a negative electrode slurry on the surface of the negative electrode current collector, wherein the coating thickness of the negative electrode slurry is more than 1 mu m to 600 mu m, and the surface density is more than 1mg/cm²To 30mg/cm²(ii) a The negative electrode paste includes a negative electrode active material, a second binder, a second conductive agent, and a second conductive agentA second solvent, wherein the proportion of the second binder is 1-15 wt% and the weight of the second conductive agent is 1-10 wt% based on the total weight of the negative electrode active material, the second binder and the second conductive agent; taking the weight of the negative electrode slurry as a reference, the solid content of the negative electrode slurry is 40-80 wt%; the binder is polyvinylidene fluoride, the conductive agent is one or more selected from carbon black, carbon nanotubes and graphene, and the solvent is N-methylpyrrolidone;

drying and rolling the coated negative current collector; wherein the drying temperature is 100-220 ℃, and the drying time is 0.1-10 h; the rolling pressure is 0.01-10T.

Optionally, the preparation step of the carbon nanotube macro-film includes:

dissolving ferrocene and thiophene into a third solvent to obtain a mixed solution; wherein the concentration of the ferrocene in the mixed solution is 5-15mg/mL, the concentration of the thiophene is 1-5 muL/mL, the third solvent comprises methanol and n-hexane, and the volume ratio of the methanol to the n-hexane is (4-15): 1;

introducing the obtained mixed solution into a cracking furnace for cracking reaction to obtain a carbon nano tube macroscopic membrane; wherein the temperature of the cracking reaction is 1000-1400 ℃, and the time is 1-30 min;

collecting the carbon nano tube macroscopic body on a substrate subjected to surface wetting by a wetting liquid in a stretching mode, wherein the wetting liquid is 5-50% by volume of ethanol water solution.

Compared with the existing lithium ion battery, the lithium ion battery has the following advantages:

firstly, the internal resistance of the lithium ion battery is reduced by adopting a multi-tab design, and the current density is higher and the reaction speed is higher at the initial stage of high-rate discharge, so that the violent exothermic reaction under the condition of single tabs is relieved, and the output power and the safety performance of the battery are improved.

Secondly, the positive and negative current collectors used in the method are carbon nano tube macroscopic films, and the whole battery structure does not relate to metal foil materials, so that the method has great advantages in the aspects of battery quality reduction and battery energy density, the surface roughness and porosity of the carbon nano tube macroscopic films are high, the active materials of the bearing electrodes are tightly bonded, material powder falling cannot occur, and the electronic transmission capability is greatly improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

fig. 1 is a schematic structural diagram of an embodiment of a lithium ion battery provided in the present disclosure.

Description of the reference numerals

1 positive electrode current collector 2 positive electrode active material 3 separator

4 negative active material 5 negative current collector

11. 12, 13, 14, 15 positive tab

51. 52, 53, 54, 55 negative electrode tab

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

As shown in fig. 1, the present disclosure provides a lithium ion battery based on a carbon nanotube film, which includes a positive plate, a negative plate, a diaphragm 3 and an electrolyte, wherein the diaphragm separates the positive plate from the negative plate, and the electrolyte is filled between the positive plate, the negative plate and the diaphragm; the positive plate includes anodal mass flow body 1 and coats in anodal active material 2 on anodal mass flow body surface, the negative pole piece includes negative current collector 5 and coats in negative active material 4 on negative current collector surface, anodal mass flow body and negative current collector are carbon nanotube macroscopic membrane respectively, every be equipped with two at least

anodal ear

11, 12, … … on the anodal mass flow body, every be equipped with two at least

negative pole ears

51, 52, … … on the negative current collector, lithium ion battery's internal resistance is less than 800m omega, preferably, lithium ion battery's internal resistance is less than 500m omega.

The carbon nano tube macroscopic film as the current collectors of the anode and the cathode can bear anode and cathode active materials and transfer charges, the surface is rough, the porosity is high, the active materials of the bearing electrode are tightly bonded, the material falling powder cannot occur, and the diaphragm cannot be damaged.

According to the present disclosure, the number of the specific tabs can be adjusted according to actual needs, 3-10 positive tabs can be arranged on each positive current collector, and 3-10 negative tabs can be arranged on each negative current collector.

Electrolytes are well known to those skilled in the art in light of this disclosure, for example, the electrolyte in the plate assembly may be in a liquid state, a semi-solid state, a quasi-solid state, or an all-solid state, the liquid electrolyte is, for example, a carbonate, a carboxylate, an ether, a sulfur-containing compound, an inorganic lithium salt, an organic lithium salt, etc., the all-solid electrolyte is, for example, a NASICON-type solid electrolyte, a perovskite-type solid electrolyte, a garnet-type solid electrolyte, a chalcogenide-type solid electrolyte, etc., the quasi-solid electrolyte includes a solvent and solid electrolyte particles, and the semi-solid electrolyte is a solid electrolyte having one side electrode free of liquid electrolyte and the other side electrode containing liquid electrolyte. Specific electrolyte compositions and types are not specifically described in detail in this disclosure.

According to the present disclosure, the positive active material includes one or more selected from lithium cobaltate, lithium manganate, lithium nickelate, nickel cobalt manganese, nickel manganese and lithium iron phosphate, and the negative active material includes one or more selected from graphite, coke, sulfur, silicon, lithium titanate, silicon carbon and graphene.

According to the present disclosure, the flexible carbon nanotube film is light and flexible, can wind, conduct electricity and generate heat, and has a tensile strength of 1 to 100000MPa, preferably 10 to 10000MPa, further preferably 100 to 1000MPa, further preferably 1000 to 100MPa, a thickness of 1 to 100000 μm, preferably 1 to 1000 μm, further preferably 10 to 500 μm, an electrical conductivity of preferably 0.1 to 1000,000S/m, more preferably 0.1 to 100,000S/m, further preferably 1 to 10,000S/m, and an areal density of more than 0.1mg/cm²To 100mg/cm²Preferably greater than 0.1mg/cm²To 10mg/cm²More preferably 1mg/cm²To 10mg/cm²The area may be more than 0 to 500m²Preferably greater than 0 to 50m²More preferably, it is more than 0 to 1m²More preferably 0.01 to 0.5m²。

In the present disclosure, the separator is a conventional battery separator, and may be selected from one or more of a woven film, a non-woven film (non-woven fabric), a microporous film, a composite film, a separator paper, and a rolled film, for example, and the details of the present disclosure are not repeated.

The present disclosure also provides a method for preparing the lithium ion battery, the method comprising:

the method is characterized in that a battery core is assembled by sequentially stacking and welding cathode plates, diaphragms, anode plates, diaphragms and cathode plates in sequence, the number of the anode plates, the diaphragms and the cathode plates in the battery core can be increased as required, but the anode plates and the cathode plates need to be separated by the diaphragms, and cathode plate lamination is adopted on two surfaces of the outermost layer of the battery core, so that the electrochemical performance of an anode material can be fully exerted;

In the present disclosure, the flexible carbon nanotube film may be prepared by an in-situ pyrolysis deposition method, in which a carbon nanotube macroscopic body is generated by pyrolyzing organic molecules, and the carbon nanotube macroscopic body is collected on the surface of a substrate to obtain the flexible carbon nanotube film.

In a preferred embodiment, the step of preparing the flexible carbon nanotube film comprises: dissolving ferrocene and thiophene into a solvent to obtain a mixed solution; wherein, the concentration of the ferrocene in the mixed solution is 0.1-10mg/mL, preferably 1-3mg/mL, the concentration of the thiophene is 1-50 muL/mL, preferably 1-5 muL/mL, the solvent comprises methanol and n-hexane, and the volume ratio of the methanol to the n-hexane is (4-15): 1; introducing the obtained mixed solution into a cracking furnace for cracking reaction to obtain a carbon nano tube macroscopic body; wherein the temperature of the cracking reaction is 1000-1400 ℃, and the time is 1-30 min; collecting the carbon nano tube macroscopic body on a substrate subjected to surface wetting by a wetting liquid in a stretching mode, wherein the wetting liquid is 5-50% by volume of ethanol water solution. The flexible carbon nanotube film prepared by the implementation mode has the advantages of high heating speed, uniform heating and low power consumption.

In the present disclosure, the positive electrode sheet may be manufactured by a self-made method or a commercially available method, and the manufacturing method thereof is well known to those skilled in the art, for example, the positive electrode sheet may be manufactured by a method including: shielding a positive tab of a positive current collector, and coating positive slurry on the surface of the positive current collector, wherein the coating thickness of the positive slurry is 1 to 500 μm, preferably 1 to 400 μm, and the surface density is 1 to 30mg/cm²Preferably 0.1 to 20mg/cm²The coating thickness can be controlled by a smooth scraper blade coating of foil with fixed thickness or a coating scraper with a micrometer screw, the length of the tab can be set according to the requirement, for example, the tab can be more than 0 to 100mm, the length of the positive current collector can be more than 0 to 5000mm, and the width can be more than 0 to 200 mm; the positive electrode slurry can comprise a positive electrode active material, a binder, a conductive agent and a solvent, wherein the proportion of the binder is 1-6 wt% and the weight of the conductive agent is 1-10 wt% based on the total weight of the positive electrode active material, the binder and the conductive agent; taking the weight of the anode slurry as a reference, the solid content of the anode slurry is 40-80 wt%, the anode slurry can be ball-milled by adopting a planetary ball mill, and the ball-milling time can be 0.5-10 h; the binder may be polyvinylidene fluoride, and the conductive agent may be selected from carbon black, carbon nanotubes andone or more of graphene, the solvent may be N-methylpyrrolidone; drying and rolling the coated positive current collector; wherein, the drying can be carried out in a forced air drying box, the drying temperature can be 100-220 ℃, and the drying time can be 0.1-10 h; the rolling can be carried out by a roller press, the rolling pressure can be 0.01-10T, and the rolling time can be 1-30 h.

In the present disclosure, the negative electrode sheet may be manufactured by self or commercially, and the manufacturing method thereof is well known to those skilled in the art, for example, the negative electrode sheet is manufactured by the following steps: shielding a negative electrode lug of a negative electrode current collector, and coating a negative electrode slurry on the surface of the negative electrode current collector, wherein the coating thickness of the negative electrode slurry is more than 0-600 mu m, and the surface density is more than 0-30 mg/cm²The coating thickness can be controlled by a smooth scraper blade coating of foil with fixed thickness or a coating scraper with a micrometer screw, the length of the tab can be set according to requirements, for example, the tab can be 1-100mm, the length of the negative current collector can be 0-5000 mm, and the width can be more than 0-200 mm; the negative electrode slurry can comprise a negative electrode active material, a binder, a conductive agent and a solvent, wherein the proportion of the binder is 1-15 wt% and the weight of the conductive agent is 1-10 wt% based on the total weight of the negative electrode active material, the binder and the conductive agent; taking the weight of the cathode slurry as a reference, the solid content of the cathode slurry is 40-80 wt%, the cathode slurry can be ball-milled by adopting a planetary ball mill, and the ball-milling time can be 0.5-10 h; the binder may be polyvinylidene fluoride, the conductive agent may be one or more selected from carbon black, carbon nanotubes and graphene, and the solvent may be N-methylpyrrolidone; drying and rolling the coated negative current collector; wherein, the drying can be carried out in a forced air drying box, the drying temperature can be 100-220 ℃, and the drying time can be 0.1-10 h; the rolling can be carried out by a roller press, the rolling pressure can be 0.01-10T, and the rolling time can be 1-30 h.

In the present disclosure, the positive electrode current collector and the negative electrode current collector are preferably carbon nanotube macroscopic films, and the carbon nanotube macroscopic films may be prepared by the following steps: dissolving ferrocene and thiophene into a solvent to obtain a mixed solution; wherein, the concentration of ferrocene in the mixed solution is 5-15mg/mL, the concentration of thiophene is 1-5 muL/mL, the solvent can comprise methanol and n-hexane, and the volume ratio of the methanol to the n-hexane can be (4-15): 1; introducing the obtained mixed solution into a cracking furnace for cracking reaction to obtain a carbon nano tube macroscopic body; wherein, the temperature of the cracking reaction can be 1000-1400 ℃, and the time can be 5-30 min; collecting the carbon nano tube macroscopic body on a substrate subjected to surface wetting by a wetting liquid in a stretching mode, wherein the wetting liquid can be 5-50% by volume of ethanol water solution.

In one embodiment, the step of adding the electrolyte to the battery case may comprise: injecting electrolyte into the battery shell in an injection glove box with the humidity of 3-10%, then placing the battery injected with the electrolyte into a vacuum box (the vacuum degree is lower than-80 kPa), standing for 10-40min, and sealing by using a heat sealing machine.

The present disclosure is further illustrated by the following examples, but is not to be construed as being limited thereby.

The reagents were all commercially available analytical reagents without specific reference to the examples of the present disclosure.

Example 1

Preparing a flexible carbon nanotube film: taking certain amount of ferrocene (controlled concentration is 2mg/mL) and thiophene (controlled concentration is 3 mu L/mL)^-1) Dissolving into mixed solution of methanol and n-hexane (volume ratio of 9: 1), and ultrasonically dispersing for 10min to uniformly mix the solution. Assembling the quartz tube, the collector and the reaction furnace, and sealing the reaction chamber; at 20 ℃ s^-1The high-temperature resistance furnace is heated to the reaction temperature of 1200 ℃, and the reaction solution is introduced into the reaction high-temperature area (the flow rate is 30 mL. h) through a peristaltic pump under the argon atmosphere^-1) (ii) a After reacting for 20min, the carbon nano tube macroscopic body can be seen to be generated from the quartz tube opening. Then spraying an ethanol water solution with the volume fraction of 20% on the surface of the substrate; then, the carbon nanotube macroscopic body generated from the reactor opening is attached to the substrate and drawn out for collection. Adopting a film forming mode of a longitudinal and transverse graticule to obtain the high-strength flexible carbon nanotube film with the thickness of10 μm, 0.5mg/cm areal density²The tensile strength is 80MPa, the resistivity is 2 omega m, the cutting is carried out to 50mm multiplied by 45mm, two lugs are respectively designed on two opposite sides to be at the same side, the length of the lug is 20mm, and the width of the lug is 15 mm.

Preparing a carbon nano tube macroscopic film: taking certain amount of ferrocene (controlled concentration is 10mg/mL) and thiophene (controlled concentration is 3 mu L/mL)^-1) Dissolving into mixed solution of methanol and n-hexane (volume ratio of 9: 1), and ultrasonically dispersing for 10min to uniformly mix the solution. Assembling the quartz tube, the collector and the reaction furnace, and sealing the reaction chamber; at 20 ℃ s^-1The high-temperature resistance furnace is heated to the reaction temperature of 1200 ℃, and the reaction solution is introduced into the reaction high-temperature area (the flow rate is 30 mL. h) through a peristaltic pump under the argon atmosphere^-1) (ii) a After reacting for 20min, the carbon nano tube macroscopic body can be seen to be generated from the quartz tube opening. Then spraying an ethanol water solution with the volume fraction of 20% on the surface of the substrate; then, the carbon nanotube macroscopic body generated from the reactor opening is attached to the substrate and drawn out for collection. And a film forming mode of a longitudinal and transverse graticule is adopted to obtain the high-strength flexible carbon nanotube film with the thickness of 8000 mu m.

Preparing a positive plate: subjecting LiCoO to condensation₂(Beijing Dangshi YJGSL-5#), Super-P (Switzerland TIMCAL), polyvinylidene fluoride (PVDF, France Arkema) are mixed with N-methyl pyrrolidone (NMP, Tianjin Mao) according to the weight ratio of 90: 4: 6 (the solid content is kept at 45 weight percent), and the mixture is put into a ball mill for ball milling for 10 hours at the rotating speed of 232 r.min^-1And obtaining the positive electrode slurry. Respectively and uniformly coating anode slurry on the carbon nanotube macroscopic film, wherein the coating thickness is 100 mu m, and the surface density is 5mg/cm². After the coating is finished, the mixture is put into an oven (120 ℃, 40 min). After drying, the substrate carrying the carbon nanotube macroscopic film is horizontally placed, NMP is dipped by a brush, and the carbon nanotube macroscopic film area which is not coated with the slurry is lightly brushed. And after the uncoated part is wetted, separating the carbon nano tube macroscopic film from the substrate. After separation, the loaded carbon nanotube macroscopic film is put into a 120 ℃ oven for drying for 20min to obtain LiCoO₂-a CNT positive plate. Subsequently LiCoO₂Rolling the CNT positive plate under the pressure of 1T of a rolling machine, and then placing the rolled CNT positive plate on a punching machine to punch a 12mm circular plate for assembling a button type power supplyUsing the pool; subjecting LiCoO to condensation₂The CNT positive plate is cut into 40mm x 30mm, wherein the size of the positive slurry is 30mm x 30mm (the residual area is reserved for manufacturing the tab).

The negative plate is artificial graphite (Shanghai fir Shuoyeng can FT-17) -Cu negative plate (the size of the negative plate is 35mm multiplied by 35mm), and the diaphragm is Shenzhen Xinmin 12mm diaphragm paper.

Assembling a positive plate, a negative plate, a diaphragm and a flexible carbon nanotube film into a battery core according to the mode shown in the figure 1, placing the battery core into a battery shell, welding a lug, welding the lug in a rivet welding mode, welding the carbon nanotube film and a metal lug with lug glue, injecting electrolyte into the battery shell in an electrolyte injection glove box under the environment with the humidity of 5%, wherein the electrolyte is New Zebra LBC322-18, then placing the battery with the injected electrolyte into a vacuum box (the vacuum degree is lower than-80 kPa), standing for 20min, and sealing by using a heat sealing machine to obtain the battery S1.

Example 2

The same as example 1 except that: the positive current collector is provided with 4 positive lugs, and the negative current collector is provided with 4 negative lugs.

Example 3

The same as example 1 except that: the positive current collector is provided with 6 positive lugs, and the negative current collector is provided with 6 negative lugs.

Example 4

The same as example 1 except that: the current collector is provided with 8 positive lugs, and the current collector is provided with 8 negative lugs.

Example 5

The same as example 1 except that: the high-strength flexible carbon nanotube film is replaced by a carbon nanotube macroscopic film with the same size (the thickness is adjusted to 10 μm during preparation).

Comparative example 1

The same as example 1 except that: the positive current collector is provided with 1 positive tab, and the negative current collector is provided with 1 negative tab.

Next, a resistance test procedure and test results of the lithium ion battery of the present disclosure are explained.

In a resistance test, at 25 ℃, a lithium ion battery is charged to a voltage of 4.2V at a constant current of 1C (nominal capacity), further charged to a current of less than or equal to 0.05C at a constant voltage of 4.2V, placed for 5min, discharged to a voltage of 3.0V at a constant current of 1C, the actual discharge capacity of the lithium ion battery is recorded, the lithium ion battery is adjusted to a 50% SOC (state of charge) with the discharge capacity as a reference (100% SOC), and the voltage of the lithium ion battery is tested after the adjustment is finished and is marked as U0. The lithium ion battery was continuously discharged for 30 seconds at a current (I1) of 4C, and the voltage of the lithium ion battery was measured after the discharge was completed and was designated as U1. Dc discharge resistance DCIR ═ (U0-U1) × 1000/I1.

Table 1 examples and comparative test results

	DCIR，mΩ
		Example 1	556
Example 2	375
		Example 3	225
Example 4	215
		Example 5	546
Comparative example 1	820

As can be seen from the resistance test results of the examples and comparative examples, the lithium ion battery provided by the present disclosure has lower internal resistance, higher output power, and good safety performance.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A lithium ion battery based on a carbon nanotube film comprises a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm separates the positive plate from the negative plate, and the electrolyte is filled among the positive plate, the negative plate and the diaphragm; the positive plate comprises a positive current collector and a positive active material coated on the surface of the positive current collector, the negative plate comprises a negative current collector and a negative active material coated on the surface of the negative current collector, the positive current collector and the negative current collector are respectively carbon nanotube macroscopic films, each positive current collector is provided with at least two positive lugs, and each negative current collector is provided with at least two negative lugs.

2. The lithium ion battery of claim 1, wherein 3-10 positive tabs are provided on each positive current collector, and 3-10 negative tabs are provided on each negative current collector.

3. The lithium ion battery of claim 1, wherein the electrolyte in the group of plates is liquid, semi-solid, quasi-solid, or all-solid.

4. The lithium ion battery of claim 1, wherein the positive active material comprises one or more selected from lithium cobaltate, lithium manganate, lithium nickelate, nickel cobalt manganese, nickel manganese, and lithium iron phosphate, and the negative active material comprises one or more selected from graphite, coke, sulfur, silicon, lithium titanate, silicon carbon, and graphene.

5. The lithium ion battery of claim 1, wherein the carbon nanotube macroscopic film has a tensile strength of 10Pa to 10000MPa, a thickness of 1 μ ι η to 1000 μ ι η, an electrical conductivity of 0.1S/m to 100,000S/m, and an areal density of greater than 0.1mg/cm²To 100mg/cm²。

6. A method of making the lithium ion battery of any of claims 1-5, comprising:

7. The production method according to claim 6, wherein the positive electrode sheet production step includes:

8. The manufacturing method according to claim 6, wherein the manufacturing step of the negative electrode sheet includes:

shielding a negative electrode lug of a negative electrode current collector, and coating a negative electrode slurry on the surface of the negative electrode current collector, wherein the coating thickness of the negative electrode slurry is more than 1 mu m to 600 mu m, and the surface density is more than 1mg/cm²To 30mg/cm²(ii) a The negative electrode slurry comprises a negative electrode active material, a second binder, a second conductive agent and a second solvent, wherein the proportion of the second binder is 1-15 wt% and the weight of the second conductive agent is 1-10 wt% based on the total weight of the negative electrode active material, the second binder and the second conductive agent; taking the weight of the negative electrode slurry as a reference, the solid content of the negative electrode slurry is 40-80 wt%; the binder is polyvinylidene fluoride, and the conductive materialThe electric agent is one or more selected from carbon black, carbon nano tubes and graphene, and the solvent is N-methyl pyrrolidone;

9. The method of claim 6, wherein the step of preparing the carbon nanotube macroscopic film comprises: