阅读说明：本技术 柔性电极纤维膜、柔性电极片及其制造方法与应用 (Flexible electrode fiber membrane, flexible electrode slice, manufacturing method and application thereof ) 是由 郭德超 郭义敏 张啟文 龙超 昝亚辉 慈祥云 韩莉珺 何凤荣 于 2020-03-25 设计创作，主要内容包括：本发明提供了柔性电极纤维膜、柔性电极片及其制造方法与应用,该方法包括：向含有热塑性粘结剂的混合物料中添加易挥发性溶剂,搅拌以形成糊状物；将糊状物在高剪切作用下进行纤维化处理,然后喷射成丝；将喷射所得的丝条牵伸,然后铺展为纤维网；将纤维网碾压成型,得到柔性电极纤维膜。柔性电极纤维膜中的活性物质、导电剂和热塑性粘结剂之间为三维网络体系,代替传统技术中的点接触体系。在增强整个柔性电极纤维膜导电性的同时,赋予柔性电极纤维膜强力的物理强度和较大的弹性模量。(The invention provides a flexible electrode fibrous membrane, a flexible electrode sheet, a manufacturing method and application thereof, wherein the method comprises the following steps: adding a volatile solvent into a mixed material containing a thermoplastic binder, and stirring to form a paste; fiberizing the paste under the action of high shear, and then spraying the paste into filaments; drafting the strand silk obtained by spraying, and then spreading the strand silk into a fiber web; and rolling and molding the fiber web to obtain the flexible electrode fiber membrane. A three-dimensional network system is formed among the active substance, the conductive agent and the thermoplastic binder in the flexible electrode fiber membrane, and the point contact system in the traditional technology is replaced. The conductivity of the whole flexible electrode fiber membrane is enhanced, and strong physical strength and large elastic modulus are given to the flexible electrode fiber membrane.)

1. A method for manufacturing a flexible electrode fiber membrane, comprising:

the method comprises the following steps: adding a volatile solvent into a mixed material containing a thermoplastic binder, and stirring to form a paste;

step two: subjecting the paste to a fiberization treatment under a high shear effect, and then spraying the paste into filaments;

step three: drafting the strand silk obtained by spraying, and then spreading the strand silk into a fiber web;

step four: and rolling and molding the fiber web to obtain the flexible electrode fiber membrane.

2. The method according to claim 1, wherein in the second step, the paste is fiberized by high shear of a screw extruder to fiberize the thermoplastic binder.

3. The manufacturing method according to claim 1, wherein in the second step, the operation of jet forming filaments is performed by a slit-type drawing device; the aperture diameter of the jet spinning die of the slit drawing device is preferably 1 μm to 100 μm, and more preferably 5 μm to 50 μm.

4. The manufacturing method according to any one of claims 1 to 3, characterized in that in the first step, a volatile solvent is added to a mixed material containing a thermoplastic binder so that the solid content of the formed paste is 30% to 80%;

preferably, the volatile solvent comprises at least one of: alkyl alcohols such as methanol, ethanol and propanol, alkyl ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydropalmiran and diglyme, and phthalein-based solvents such as diethyl methyl phthalide, dimethyl ethyl phthalide and N-methyl pyrrolidone; among them, isopropyl alcohol or tetrahydrofuran is preferable.

5. The manufacturing method according to any one of claims 1 to 3, wherein in the first step, the mixed material comprises uniformly mixed active substances, conductive agents and thermoplastic binders; preferably, the first and second electrodes are formed of a metal,

the active substance comprises at least one of the following: lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickelate, lithium nickel cobalt manganese oxide, lithium manganese phosphate, lithium nickel cobalt aluminate, lithium titanate, graphite, expanded graphite, graphene oxide, carbon nanotubes, carbon nanofibers, mesocarbon microspheres, hard carbon, activated carbon, fullerene and silicon carbon materials;

the conductive agent includes at least one of: metal powder, acetylene black, ketjen black, furnace black, conductive carbon black, conductive graphite, carbon nanotubes, carbon fibers, graphene; more preferably acetylene black, ketjen black or conductive carbon black;

the thermoplastic binder includes at least one of: polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, acrylic, other polyolefins and copolymers thereof, polysulfone, polyphenylene oxide, carboxymethylcellulose; more preferably polytetrafluoroethylene or polyvinyl chloride.

6. The production method according to claim 5, wherein the mass ratio of the active material, the conductive agent, and the thermoplastic binder is 1:0.01 to 0.2:0.05 to 0.5, preferably 1:0.01 to 0.1:0.05 to 0.2.

7. A flexible electrode fiber membrane obtained by the production method according to any one of claims 1 to 6.

8. The flexible electrode fiber membrane of claim 7, wherein the thickness of the flexible electrode fiber membrane is 30-150 μm, preferably 70-120 μm.

9. A flexible electrode sheet comprising the flexible electrode fibrous membrane according to claim 7 or 8.

10. The flexible electrode sheet of claim 9, comprising: the flexible electrode fiber membrane and the flexible current collector coated with the conductive adhesive.

11. The flexible electrode sheet of claim 10, wherein: the flexible current collector includes at least one of: graphite paper, carbon fiber paper, carbon nanotube paper, carbon cloth, polyester fiber, polyamide fiber, polyacrylonitrile fiber, polyolefin fiber, polyvinyl alcohol fiber, polyurethane fiber, viscose fiber, cuprammonium fiber, acetate fiber, cotton, hemp, wool and silk; among them, carbon fiber paper or carbon nanotube paper is preferable.

12. The flexible electrode sheet according to claim 9 or 10, wherein the flexible electrode fibrous membrane is thermally compounded with a flexible current collector coated with a conductive adhesive; the temperature of the thermal compounding is preferably 25 ℃ to 300 ℃, more preferably 100 ℃ to 180 ℃.

13. Use of the flexible electrode fibrous membrane of claim 7 or 8 or the flexible electrode sheet of any one of claims 10 to 13 in the manufacture of an energy storage device.

14. An energy storage device, comprising a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet and/or the negative electrode sheet is the flexible electrode sheet according to any one of claims 9 to 12.

Technical Field

The invention belongs to the technology related to an energy storage device, and particularly relates to a flexible electrode fibrous membrane, a flexible electrode slice, a manufacturing method and application thereof.

Background

Currently, lithium ion secondary batteries, super capacitors, lithium air batteries, etc. have become energy storage devices for many card-type or wearable smart devices, and the usage scenario often encountered by the devices is that the devices need to be put in a wallet or a pocket to be carried around. Since energy storage devices are bulky and important, they are not well adjustable during assembly, and product developers are always limited by the size, shape and flexibility of the energy storage device when designing a new smart device. The shape of most smart devices is therefore dependent on the shape of their energy storage means.

Generally, an electrode plate of an energy storage device is prepared by mixing an active substance, a conductive agent, a binder and a solvent capable of dissolving the binder into a slurry, and coating the slurry on an aluminum foil or copper foil current collector, wherein the used binder mainly comprises polyvinylidene fluoride (PVDF), styrene-butadiene rubber emulsion, polyacrylonitrile, polyacrylate, polystyrene acrylate and the like, and the used solvent mainly comprises N-methyl pyrrolidone, ethanol, acetone, deionized water and the like.

The electrode plate for the energy storage device is prepared by the method, and the active substance, the conductive agent and the binder are in point contact. When the electrode plate is bent or twisted to a certain degree, active substances, conductive agents and binders in the electrode plate are easy to fall off from a current collector, and the capacity of the energy storage device is rapidly attenuated.

Disclosure of Invention

The invention provides a novel flexible electrode fiber membrane, a flexible electrode sheet, a manufacturing method and application thereof.

In a first aspect, the present invention provides a method for manufacturing a flexible electrode fiber membrane, comprising:

the method comprises the following steps: adding a volatile solvent into a mixed material containing a thermoplastic binder, and stirring to form a paste;

step two: subjecting the paste to a fiberization treatment under a high shear effect, and then spraying the paste into filaments;

step three: drafting the strand silk obtained by spraying, and then spreading the strand silk into a fiber web;

step four: and rolling and molding the fiber web to obtain the flexible electrode fiber membrane. .

On this basis, the formation of the paste is carried out in a high-speed mixer, with a stirring speed of 10000-20000rpm and a stirring time of 30-60 min.

On this basis, the paste is fiberized by the high shear action of a screw extruder in order to fiberize the thermoplastic binder. On the basis, a slit type drafting device is adopted to carry out jet spinning operation; the aperture diameter of the jet spinning die of the slit drawing device is preferably 1 μm to 100 μm, and more preferably 5 μm to 50 μm.

Accordingly, the filament diameter is preferably 1 μm to 100. mu.m, more preferably 5 μm to 50 μm

If the yarn diameter is too small, problems such as clogging of spinneret holes and yarn breakage tend to occur, but if the yarn diameter is too small, problems such as yarn orientation and poor appearance tend to occur, and yarn deformation and yarn breakage during drawing tend to occur due to too heavy mass per unit length.

In some embodiments, the aperture diameter of the jet-spinning die of the slot draw frame is preferably 5 μm to 30 μm, for example: 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, and the like.

On this basis, volatile solvents are added to the mixture containing the thermoplastic binder so that the paste formed has a solids content of 30% to 80%, preferably 30% to 50%, for example: 30%, 31%, 33%, 35%, 40%, 45%, 50%, etc.

In some embodiments, the volatile solvent comprises at least one of: alkyl alcohols such as methanol, ethanol and propanol, alkyl ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydropalmiran and diglyme, and phthalein-based solvents such as diethyl methyl phthalide, dimethyl ethyl phthalide and N-methyl pyrrolidone; among them, isopropyl alcohol or tetrahydrofuran is preferable.

On the basis, the mixed material comprises the active substance, the conductive agent and the thermoplastic binder which are uniformly mixed.

The degree of uniform mixing determines the degree of fiberization of the thermoplastic binder by the powerful shearing forces in the screw extruder.

In some embodiments, the active substance comprises at least one of: lithium iron phosphate, lithium manganate, lithium cobaltate, lithium nickelate, lithium nickel cobalt manganese oxide, lithium manganese phosphate, lithium nickel cobalt aluminate, lithium titanate, graphite, expanded graphite, graphene oxide, carbon nanotubes, carbon nanofibers, mesocarbon microspheres, hard carbon, activated carbon, fullerene and silicon carbon materials.

In a preferred embodiment, the flexible electrode fiber film of the positive electrode plate comprises lithium iron phosphate or lithium nickel cobalt manganese oxide, and the flexible electrode fiber film of the negative electrode plate comprises graphene or carbon nanotubes.

In some embodiments, the conductive agent comprises at least one of: metal powder, acetylene black, ketjen black, furnace black, conductive carbon black, conductive graphite, carbon nanotubes, carbon fibers, graphene; more preferably acetylene black, ketjen black or conductive carbon black.

In some embodiments, the thermoplastic binder comprises at least one of: polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, acrylic, other polyolefins and copolymers thereof, polysulfone, polyphenylene oxide, carboxymethylcellulose; more preferably polytetrafluoroethylene or polyvinyl chloride.

On the basis, the mass ratio of the active substance, the conductive agent and the thermoplastic binder is 1:0.01-0.2:0.05-0.5, preferably 1:0.01-0.1:0.05-0.2, such as: 0.01:0.05-0.2, 0.02:0.05-0.2, 0.03:0.05-0.2, 0.04:0.05-0.2, 0.05:0.05-0.2, 0.06:0.05-0.2, 0.07:0.05-0.2, 0.08:0.05-0.2, 0.09:0.05-0.2, 0.1:0.05-0.2, 0.01: 0.01-0.05: 1:0.09: 0.06: 1:0.05: 1:0.01-0.1: 0.05: 1:0.01: 0.1: 0.07: 1:0.01-0.1: 0.08: 1: 0.01-0.09: 1:0.01: 0.08: 1:0.01-0.1: 0.09: 1:0.01-0.1: 0.01: 0.1: 0.15: 1:0.01-0.1: 1:0.1: 1, and so on.

In some embodiments, the mass ratio of the active material, the conductive agent, and the thermoplastic binder is 1:0.02: 0.09.

In some embodiments, the mass ratio of the active material, the conductive agent, and the thermoplastic binder is 1:0.06: 0.19.

In a second aspect, the present invention provides a flexible electrode fibre membrane produced by the method of the first aspect.

On the basis, the thickness of the flexible electrode fiber membrane is 30-150 μm, preferably 70-120 μm, for example: 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, and the like.

In a third aspect, the present invention provides a flexible electrode sheet comprising the flexible electrode fibrous membrane of the second aspect.

On the basis, the flexible electrode sheet comprises a flexible electrode fiber membrane and a flexible current collector coated with conductive adhesive.

On this basis, the flexible current collector comprises at least one of the following: graphite paper, carbon fiber paper, carbon nanotube paper, carbon cloth, polyester fiber, polyamide fiber, polyacrylonitrile fiber, polyolefin fiber, polyvinyl alcohol fiber, polyurethane fiber, viscose fiber, cuprammonium fiber, acetate fiber, cotton, hemp, wool and silk; among them, carbon fiber paper or carbon nanotube paper is preferable.

On the basis, the flexible electrode plate is formed by thermally compounding the flexible electrode fibrous membrane and a flexible current collector coated with conductive adhesive; the temperature of the thermal compounding is preferably from 25 ℃ to 300 ℃, more preferably from 100 ℃ to 180 ℃, for example: 100 deg.C, 110 deg.C, 120 deg.C, 130 deg.C, 140 deg.C, 150 deg.C, 160 deg.C, 170 deg.C, 180 deg.C, etc.

In a fourth aspect, the invention provides an application of the flexible electrode fiber membrane of the second aspect or the flexible electrode sheet of the third aspect in preparing an energy storage device.

In a fifth aspect, the invention provides an energy storage device, which comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet and/or the negative electrode sheet is the flexible electrode sheet of the third aspect.

Through the technical scheme, compared with the prior art, the invention can at least obtain the following technical effects:

the preparation method of the electrode plate of the traditional energy storage device is mainly characterized in that an active substance, a conductive agent, a binder and a solvent capable of dissolving the binder are mixed into slurry and then coated on an aluminum foil or copper foil current collector, the used binder mainly comprises polyvinylidene fluoride (PVDF), styrene-butadiene rubber emulsion, polyacrylonitrile, polyacrylate, polystyrene acrylate and the like, and the used solvent mainly comprises N-methyl pyrrolidone, ethanol, acetone, deionized water and the like. The electrode plate for the energy storage device is prepared by the method, and the active substance, the conductive agent and the binder are in point contact. When the electrode plate is bent or twisted to a certain degree, active substances, conductive agents and binders in the electrode plate are easy to fall off from a current collector, and the capacity of the energy storage device is rapidly attenuated.

The invention utilizes the high shearing action to enable the thermoplastic adhesive to be fiberized, and enables a strong three-dimensional network system to be formed among the active substance, the conductive agent and the adhesive in the flexible electrode fiber membrane, and the three-dimensional network system replaces the traditional point contact, thereby enhancing the conductivity and the uniformity of the whole flexible electrode fiber membrane, and simultaneously endowing the flexible electrode fiber membrane with strong physical strength and larger elastic modulus. On the basis, the flexible electrode fiber film and the flexible current collector coated with the conductive adhesive are compounded by using a thermal compound machine to obtain the flexible electrode plate, so that the contact between the flexible electrode fiber film and the flexible current collector is also a three-dimensional network system, and the flexible electrode fiber film is not easy to fall off from the flexible current collector. Meanwhile, the flexible electrode plate can be cut into any shape through a splitting machine so as to meet the requirements of energy storage devices in different shapes. In this way, the flexible electrode sheet can be made into any shape and can be bent at any angle without irreversible damage.

Drawings

Fig. 1 is a bending test of a negative electrode sheet provided in example 1 of the present invention;

fig. 2 shows a bending test of the positive electrode sheet provided in example 2 of the present invention.

Detailed Description