CN106549185A - A kind of lithium ion battery with integral structure and preparation method thereof - Google Patents

Abstract

The invention relates to the field of lithium ion battery preparation, in particular to a lithium ion battery with an integrated structure and a preparation method thereof. The positive electrode, diaphragm and negative electrode of the lithium ion battery are formed by one-time spinning process, and the positive/negative electrode active material, conductive agent and binder are dispersed in a solvent according to a certain ratio to obtain the positive/negative electrode spinning solution, and the polymer resin, Inorganic particles, etc. are dispersed in a solvent according to a certain ratio to obtain a separator spinning solution, and the positive electrode spinning and drying, the separator spinning and drying, the negative electrode spinning and drying are performed on the surface of the current collector in sequence, and a new lithium-ion battery with an integrated structure is obtained. The invention integrates the positive electrode, the negative electrode and the separator of the lithium-ion battery, simplifies the internal structure and assembly process of the battery, and improves the interface contact characteristics between the electrode and the separator. The lithium-ion battery prepared by this method has excellent comprehensive performance and is easy to be large-scale production advantages.

Description

A kind of lithium ion battery with integrated structure and preparation method thereof

technical field

The invention relates to the field of lithium ion battery preparation, in particular to a lithium ion battery with an integrated structure and a preparation method thereof.

Background technique

Traditional lithium-ion batteries are mainly composed of four parts: positive electrode, negative electrode, electrolyte and separator. The electrode is mainly obtained by coating the slurry on the surface of the current collector, drying, and compacting, and finally obtaining the positive/negative electrode sheet. In the process of assembling the battery, it is necessary to align the separator between the positive and negative electrodes, and finally obtain the cell assembly through the lamination or winding process. The battery assembly process of this process is cumbersome, and the automation is not easy to improve. And as the key material of lithium-ion batteries, commercialized lithium battery separators are mainly polyethylene and polypropylene microporous membranes, but due to the limitations of the properties of the membrane materials themselves, they cannot be used in the field of power lithium-ion batteries.

Aiming at the shortcomings of traditional polyolefin separators, the researchers developed a lithium battery separator with a ceramic coating, which combines the advantages of the flexibility of the organic base film and the high temperature resistance of the ceramic material, and can prevent the large-area positive/negative electrode of the battery from being damaged to a certain extent. short circuit and explosion accidents. Studies have found that although the ceramic coating can improve the heat resistance of the separator, the electrical performance of the battery is limited because the interface structure between the electrode and the separator becomes more complex and the internal resistance of the battery increases. Moreover, achieving alignment and good contact between the electrode sheets and the separator is also a difficult problem to solve during the assembly process of lithium-ion batteries.

In response to the above problems, the Chinese invention patent (publication number CN102055014A) coated an organic coating whose main component is methyl acetate on the surface of the electrode. After 500 cycles of the battery, the capacity remained above 90%, showing good cycle performance. . However, under the working conditions of high-current charging and discharging, the organic coating is prone to shrinkage and deformation, which may cause a short circuit inside the battery and cause serious accidents.

Contents of the invention

The object of the present invention is to provide a novel lithium-ion battery with an integrated structure and a preparation method thereof. The lithium-ion battery prepared by this method has the advantages of simple preparation process, high energy density, good flexibility, arbitrary shape design, and low cost. And other advantages, can meet the needs of large-scale industrial production.

Technical scheme of the present invention is:

A lithium-ion battery with an integrated structure. The positive electrode, separator and negative electrode of the lithium-ion battery are formed through a spinning process at one time, and the positive electrode spinning solution, separator spinning solution and negative electrode spinning solution are spun and dried on the surface of the current collector in sequence. , the interface between the three is in close contact.

In the lithium-ion battery with an integrated structure, the positive/negative spinning liquid is a suspension containing positive/negative active materials, conductive agents and binders, and the raw material composition of the positive/negative spinning liquid is: 10-100 mass 1-20 parts by mass of positive/negative electrode active material, 1-20 parts by mass of conductive agent, 1-20 parts by mass of binder, and 100-10000 parts by mass of solvent.

In the lithium-ion battery with an integrated structure, the diaphragm spinning liquid is a suspension containing polymer resin and inorganic particles, and the raw material composition of the diaphragm spinning liquid is: 10-100 parts by mass of polymer resin, 1-200 parts by mass Conductive agent, 100-10000 mass parts solvent;

Among them, the polymer resin is polyvinylidene fluoride, polyacrylonitrile, polyphenylene ether, polyvinyl alcohol, polyimide, polyamic acid, polyethylene oxide or polytetramethylpentene; One or more of aluminum, titanium oxide, zirconium oxide, silicon oxide, and molecular sieves with microporous or mesoporous structures.

For the lithium ion battery with an integrated structure, the spinning process is solution spinning or electrospinning.

The lithium-ion battery with an integrated structure means that the positive electrode, diaphragm, and negative electrode of the battery are laminated into an integral structure through a spinning process in sequence, and are pressed by hot rolling without gaps between them.

The preparation method of the lithium-ion battery with an integrated structure, the preparation method comprises: preparation of the lithium-ion battery positive/negative electrode and diaphragm spinning solution, spinning and drying to obtain an integrated battery cell assembly, assembling the battery, using the solution Spinning or electrospinning process, on the surface of the current collector of the lithium-ion battery, the positive or negative electrode is spun and dried in sequence, the separator is spun and dried, the negative or positive electrode is spun and dried, and the integrated cell assembly is obtained after hot rolling .

In the preparation method of the lithium-ion battery with an integrated structure, the drying includes positive/negative active layer drying and separator layer drying, the drying temperature is 60°C-200°C, and the drying time is 30min-200min.

In the preparation method of the lithium-ion battery with an integrated structure, the diameter of the fiber obtained after spinning the positive/negative electrode spinning solution is 50nm-1000nm.

In the preparation method of the lithium-ion battery with an integrated structure, the diameter of the fiber obtained after spinning the diaphragm spinning liquid is 100nm-500nm.

In the preparation method of the lithium-ion battery with an integrated structure, hot roll pressing is carried out at 100°C-200°C with a pressure of 10N/cm ² -1000N/cm ² .

Advantage and beneficial effect of the present invention are:

1. Based on the defects of the traditional lithium-ion battery components and structure, the present invention proposes the following idea: the positive electrode active layer, the diaphragm layer and the negative electrode active layer are sequentially constructed on the surface of the battery current collector through a spinning process to obtain a battery cell with an integrated structure The thickness and shape of the component can be freely designed, the flexibility is good, the contact characteristics between the electrode and the diaphragm are fully improved, and a lithium-ion battery with excellent performance is prepared. This method can comprehensively improve the safety and electrical performance of the lithium-ion battery.

2. The preparation method of the lithium-ion battery with an integrated structure according to the present invention uses the spinning process to improve the automatic production of the lithium-ion battery. It has the characteristics of simple process, short process cycle, energy saving and environmental protection, and is suitable for large-scale production.

3. The present invention integrates the positive electrode, the negative electrode and the diaphragm of the lithium ion battery, simplifies the internal structure and assembly process of the battery, and improves the interface contact characteristics between the electrode and the diaphragm. The lithium ion battery prepared by this method has superior comprehensive performance and is easy to scale up. Large size production and other advantages.

detailed description

In a specific embodiment, the preparation method of the lithium-ion battery with an integrated structure of the present invention is to disperse the positive/negative electrode active material, conductive agent and binder in a solvent according to a certain ratio to obtain the positive/negative electrode spinning solution, and Polymer resin, inorganic particles, etc. are dispersed in a solvent according to a certain ratio to obtain a diaphragm spinning solution, and the positive electrode spinning and drying, diaphragm spinning and drying, negative electrode spinning and drying are carried out sequentially on the surface of the current collector, and a new type of lithium ion with an integrated structure is obtained. Ion battery, comprising the steps of:

(1) Preparation of lithium-ion battery positive/negative electrodes and diaphragm spinning solution;

(2) Spinning sequentially on the surface of the current collector to prepare the positive electrode layer, separator layer and negative electrode layer, each layer needs to be dried after spinning; wherein, the thickness of the positive electrode layer is 30-100 microns; the thickness of the diaphragm layer is 20-60 microns ; The thickness of the negative electrode layer is 30-100 microns;

(3) The integrated battery cell assembly obtained above is hot-rolled under certain conditions, dried, and finally assembled into a battery.

The hot roll pressing means that the integrated battery cell assembly is pressed at 100°C-200°C with a pressure of 10N/cm ² -1000N/cm ² to obtain a lithium-ion battery with an integrated structure.

The positive electrode, separator and negative electrode of the lithium-ion battery are formed by one-time spinning process. The spinning process is solution spinning or electrospinning. One-time forming means that the positive electrode, separator and negative electrode of the battery are laminated into a whole through the spinning process in sequence. structure, and after certain conditions of hot rolling, there is no obvious gap between each other. The positive electrode spinning solution, the separator spinning solution and the negative electrode spinning solution are spun and dried on the surface of the current collector in sequence, and the interface between the three is closely contacted. The shape and size of the battery can be freely designed, and the flexibility and safety are high. Drying includes positive/negative active layer drying and separator layer drying, the drying temperature is 60°C-200°C, and the drying time is 30min-200min.

The positive/negative spinning solution is a suspension containing positive/negative active materials, conductive agents and binders. The raw material composition of the positive/negative spinning solution is: 10-100 parts by mass of positive/negative active materials, 1-20 parts by mass Conductive agent, 1-20 mass parts binder, 100-10000 mass parts solvent. The preferred raw material composition of the positive/negative spinning solution is: 60-85 parts by mass of positive/negative electrode active materials, 3-12 parts by mass of conductive agent, 3-12 parts by mass of binder, and 400-800 parts by mass of organic solvent. Positive electrode active materials include lithium iron phosphate, lithium cobaltate, lithium manganese oxide, ternary materials, etc. Negative electrode active materials include graphite, mesocarbon microspheres, lithium titanate, silicon-based materials, etc. Conductive agents include acetylene black, graphite, Ketjen black, etc., binders include polyvinylidene fluoride, sodium carboxymethyl cellulose, etc. After the positive/negative electrode spinning solution is spun, the fiber diameter obtained is 50nm-1000nm.

The diaphragm spinning solution is a suspension containing polymer resin and inorganic particles. The raw material composition of the diaphragm spinning solution is: 10-100 parts by mass of polymer resin, 1-200 parts by mass of inorganic particles, and 100-10000 parts by mass of solvent. The preferred raw material composition of the diaphragm spinning solution is: 20-50 parts by mass of polymer resin, 80-160 parts by mass of inorganic particles, and 500-2000 parts by mass of organic solvent. The polymer resin is polyvinylidene fluoride, polyacrylonitrile, polyphenylene ether, polyvinyl alcohol, polyimide, polyamic acid, polyethylene oxide or polytetramethylpentene, etc.; the inorganic particles are alumina , titanium oxide, zirconium oxide, silicon oxide, and molecular sieve materials with microporous or mesoporous structures. After the membrane spinning solution is spun, the fiber diameter obtained is 100nm-500nm.

In order to make the technical solutions and advantages of the present invention clearer, the following will describe in detail in conjunction with specific embodiments.

Example 1

0.8 g of lithium iron phosphate nanoparticles, 0.1 g of acetylene black, and 0.1 g of polyvinylidene fluoride were slowly added to 10 ml of dimethylformamide in sequence, and mixed uniformly by ball milling to obtain a positive electrode spinning solution.

Slowly add 0.75 g of graphite powder, 0.1 g of carbon black, and 0.15 g of sodium carboxymethylcellulose into 10 ml of dimethylformamide in sequence, and mix uniformly by ball milling to obtain a negative electrode spinning solution.

Slowly add 0.4 g of polyvinylidene fluoride and 0.2 g of nano-silicon oxide into 10 ml of nitrogen-methylpyrrolidone in turn, and mix them uniformly by ball milling to obtain a diaphragm spinning solution.

Using a spinneret with an aperture of 0.1mm and a spinning speed of 200m/min, a 50-micron-thick positive electrode layer, a 30-micron diaphragm layer, and a 50-micron-thick negative electrode layer were successively obtained on the surface of the aluminum current collector by solution spinning. After silking, it is dried at a constant temperature of 120°C for 2 hours, and finally rolled at 150°C with a pressure of 100N/cm ² to obtain an integrated battery.

The above cells were filled with liquid and then assembled into button cells for testing.

Spinning layer morphology: the positive/negative electrode fibers have good continuity, with a diameter of 250nm, and the diameter of the diaphragm layer fibers is 100nm.

Battery test results: The discharge capacity of the battery at 10C is 50% of that at 0.2C rate.

Under the condition of 2.0C charge and discharge, the discharge capacity of the battery after 100 cycles still maintains about 96% of the initial discharge capacity.

Example 2

0.9 g of lithium manganate nanoparticles, 0.05 g of Ketjen black, and 0.05 g of polyvinylidene fluoride were slowly added to 20 ml of dimethylacetamide in sequence, and mixed uniformly by ball milling to obtain a positive electrode spinning solution.

Slowly add 0.8 g of mesophase carbon microspheres, 0.1 g of carbon black, and 0.1 g of sodium carboxymethylcellulose into 15 ml of deionized water in sequence, stir and mix evenly to obtain a negative electrode spinning solution.

Slowly add 0.5 g of polyphenylene ether and 1.0 g of nano-alumina into 30 ml of dimethylformamide in sequence, and mix them uniformly by ball milling to obtain a diaphragm spinning solution.

Using a spinneret with an aperture of 0.2mm and a spinning speed of 300m/min, a 70-micron-thick positive electrode layer, a 40-micron diaphragm layer, and a 60-micron-thick negative electrode layer were sequentially obtained on the surface of the aluminum current collector by solution spinning. After silking, it is dried at a constant temperature of 140°C for 2 hours, and finally rolled at 120°C with a pressure of 400N/cm ² to obtain an integrated cell.

The above cells were filled with liquid and then assembled into button cells for testing.

Spinning layer morphology: the positive/negative electrode fibers have good continuity, with a diameter of 200nm, and the diameter of the diaphragm layer fibers is 150nm.

Battery test results: the discharge capacity of the battery at 10C is 48% of that at 0.2C rate.

Under the condition of 2.0C charge and discharge, the discharge capacity of the battery after 100 cycles still maintains about 95% of the initial discharge capacity.

Example 3

Slowly add 0.8 g of lithium cobaltate nanoparticles, 0.15 g of Ketjen black, and 0.05 g of sodium carboxymethylcellulose into 12 ml of dimethylacetamide in sequence, and mix uniformly by ball milling to obtain a positive electrode spinning solution.

Slowly add 0.8 g of graphite powder, 0.1 g of carbon black, and 0.1 g of sodium carboxymethylcellulose into 10 ml of deionized water in sequence, stir and mix evenly to obtain a negative electrode spinning solution.

Slowly add 2 grams of polyvinyl alcohol and 8.0 grams of nano-alumina into 20 ml of deionized water in sequence, stir and mix evenly to obtain a diaphragm spinning solution.

Using a spinneret with an aperture of 0.3mm, a spinning speed of 100m/min, and an electrostatic voltage of 20KV, a 40-micron-thick positive electrode layer, a 20-micron diaphragm layer, and a 40-micron-thick negative electrode were sequentially obtained on the surface of the aluminum current collector by electrospinning. Each layer is dried at a constant temperature of 120°C for 3 hours after spinning, and finally rolled at 100°C with a pressure of 300N/cm ² to obtain an integrated cell.

The above cells were filled with liquid and then assembled into button cells for testing.

Spinning layer morphology: the positive/negative electrode fibers have good continuity, with a diameter of 260nm, and the diameter of the diaphragm layer fibers is 110nm.

Battery test results: the discharge capacity of the battery at 10C is 55% of that at 0.2C rate.

Under the condition of 2.0C charge and discharge, the discharge capacity of the battery after 100 cycles still maintains about 96% of the initial discharge capacity.

Example 4

Slowly add 0.8 g of nickel-cobalt-manganese ternary material, 0.1 g of Ketjen black, and 0.1 g of polyvinylidene fluoride into 20 ml of dimethylacetamide in sequence, and mix uniformly by ball milling to obtain a positive electrode spinning solution.

Slowly add 0.85 g of graphite powder, 0.05 g of carbon black, and 0.1 g of sodium carboxymethylcellulose into 15 ml of deionized water in sequence, stir and mix evenly to obtain a negative electrode spinning solution.

Slowly add 1 gram of polyacrylonitrile and 0.5 gram of NaA zeolite powder (particle size: 200 nm) into 30 ml of dimethylacetamide in sequence, and mix uniformly by ball milling to obtain a diaphragm spinning solution.

Using a spinneret with an aperture of 0.2mm, a spinning speed of 200m/min, and an electrostatic voltage of 15KV, an 80-micron-thick positive electrode layer, a 30-micron diaphragm layer, and a 70-micron-thick negative electrode were sequentially obtained on the surface of the aluminum current collector by electrospinning. Each layer is dried at a constant temperature of 150°C for 2 hours after spinning, and finally rolled at 120°C with a pressure of 500N/cm ² to obtain an integrated cell.

The above cells were filled with liquid and then assembled into button cells for testing.

Spinning layer morphology: the positive/negative electrode fibers have good continuity, with a diameter of 200nm, and the diameter of the diaphragm layer fibers is 130nm.

Battery test results: the discharge capacity of the battery at 10C is 56% of that at 0.2C rate.

Under the condition of 2.0C charge and discharge, the discharge capacity of the battery after 100 cycles still maintains about 95% of the initial discharge capacity.

Example 5

0.8 g of lithium iron phosphate, 0.1 g of acetylene black, and 0.1 g of polyvinylidene fluoride were slowly added to 30 ml of dimethylformamide in sequence, and mixed uniformly by ball milling to obtain a positive electrode spinning solution.

Slowly add 0.8 g of lithium titanate, 0.1 g of carbon black, and 0.1 g of sodium carboxymethyl cellulose into 20 ml of deionized water in sequence, stir and mix evenly to obtain a negative electrode spinning solution.

2 g of polyimide and 1.0 g of SBA15 zeolite powder (particle size: 100 nm) were slowly added to 30 ml of nitrogen methyl pyrrolidone in sequence, and mixed uniformly by ball milling to obtain a diaphragm spinning solution.

Using a spinneret with an aperture of 0.5mm, a spinning speed of 400m/min, and an electrostatic voltage of 25KV, a 60-micron-thick positive electrode layer, a 40-micron diaphragm layer, and a 50-micron-thick negative electrode were sequentially obtained on the surface of the aluminum current collector by electrospinning. Each layer is dried at a constant temperature of 130°C for 2 hours after spinning, and finally rolled at 100°C with a pressure of 200N/cm ² to obtain an integrated cell.

The above cells were filled with liquid and then assembled into button cells for testing.

Spinning layer morphology: the positive/negative electrode fibers have good continuity, with a diameter of 350nm, and the diameter of the diaphragm layer fibers is 200nm.

Battery test results: the discharge capacity of the battery at 10C is 60% of that at 0.2C rate.

Under the condition of 2.0C charge and discharge, the discharge capacity of the battery after 100 cycles still maintains about 94% of the initial discharge capacity.

The results of the examples show that the novel structure lithium-ion battery and its preparation method provided by the present invention, because the positive electrode, the separator and the negative electrode are organically integrated by the spinning method, the integration of the electrode and the separator is realized, and the prepared lithium-ion battery It is superior to traditional lithium-ion batteries in terms of high temperature resistance and lithium ion transfer efficiency, and has the advantages of simple assembly process and low cost, no need for expensive production equipment, simple operation, high production efficiency, and large-scale industrial production. .

Claims (10)

1. a kind of lithium ion battery with integral structure, it is characterised in that the positive pole of lithium ion battery, every , by spinning technique one-shot forming, positive pole spinning solution, barrier film spinning solution and negative pole spinning solution exist successively for film and negative pole Collection liquid surface spinning, drying, between three, interracial contact is tight.

2. according to the lithium ion battery with integral structure described in claim 1, it is characterised in that just/ Negative spinning solution is the suspension containing positive/negative active material, conductive agent and adhesive, positive/negative spinning solution raw material Consist of：10～100 mass parts positive/negative active materials, 1～20 mass parts conductive agent, 1～20 mass parts Adhesive, 100～10000 mass parts solvents.

3. according to the lithium ion battery with integral structure described in claim 1, it is characterised in that barrier film Spinning solution is the suspension containing macromolecule resin, inorganic particulate, and barrier film spinning solution raw material is consisted of：10～100 Mass parts macromolecule resin, 1～200 mass parts conductive agent, 100～10000 mass parts solvents；

Wherein, macromolecule resin be Kynoar, polyacrylonitrile, polyphenylene oxide, polyvinyl alcohol, polyimides, Polyamic acid, one amylene of PEO or poly- tetramethyl；Inorganic particulate be aluminum oxide, titanium oxide, zirconium oxide, Silica and the molecular sieve with micropore or meso-hole structure one or more.

4. the lithium ion battery with integral structure according to claim 1, it is characterised in that spinning Technique is solution-polymerized SBR or electrostatic spinning.

5. the lithium ion battery with integral structure according to claim 1, it is characterised in that once Shaping refers to that the positive pole of battery, barrier film, negative pole pass sequentially through spinning technique and be laminated into an overall structure, and Jing Overheated roll-in, it is very close to each other to each other.

6. the preparation method of the lithium ion battery with integral structure described in a kind of one of claim 1-5, Characterized in that, the preparation method includes：The preparation of lithium ion battery positive/negative, barrier film spinning solution, spinning, It is dried and obtains integrated battery core component, assembles battery, using solution-polymerized SBR or electrostatic spinning process, in lithium ion The collection liquid surface of battery carries out positive or negative pole spinning, drying successively, and barrier film spinning, drying, negative or positive pole are spun Silk, dry, the integrated battery core component of acquisition after hot-rolling pressure.

7. the preparation method of the lithium ion battery with integral structure according to claim 6, its feature It is that drying includes that positive/negative active layer is dried and membrane layer is dried, and baking temperature is 60 DEG C～200 DEG C, the time For 30min～200min.

8. the preparation method of the lithium ion battery with integral structure according to claim 6, its feature It is that the fibre diameter that positive/negative spinning solution is obtained after spinning is 50nm～1000nm.

9. the preparation method of the lithium ion battery with integral structure according to claim 6, its feature It is that the fibre diameter that barrier film spinning solution is obtained after spinning is 100nm～500nm.

10. the preparation method of the lithium ion battery with integral structure according to claim 6, which is special Levy and be, hot-rolling pressure is at 100 DEG C～200 DEG C, using 10N/cm²～1000N/cm²Pressure pressed System.