阅读说明：本技术 一种电池正极片、软包装锂氟化碳一次电池及其制备方法 (Battery positive plate, flexible-package lithium fluorocarbon primary battery and preparation method thereof ) 是由 阳晓霞 白宝生 冯辉 段征 于 2020-06-29 设计创作，主要内容包括：本发明公开了一种电池正极片,包括正极集流体,所述正极集流体的外表面涂覆有正极活性物质涂层；正极活性物质涂层包括正极活性物质、导电剂和粘结剂；正极活性物质采用氟化碳或者采用以氟化碳为主要活性物质的混合物；氟化碳的孔隙率范围为5～50％；氟化碳孔隙的尺寸包括大孔、中孔和微孔中的一种或多种。本发明还提供了软包装锂氟化碳一次电池及其制备方法,本发明优选具有丰富孔隙结构、高比表面的氟化碳材料作为正极活性物质,氟化碳的特殊结构和形貌预留了可容纳反应产物的空间、限制了反应产物的存在形态,大大降低了正极片的放电膨胀。结合合理的正负电极面容量设计、电极压实密度设计,实现放电过程中正负极片厚度互平衡。(The invention discloses a battery positive plate, which comprises a positive current collector, wherein the outer surface of the positive current collector is coated with a positive active material coating; the positive active material coating comprises a positive active material, a conductive agent and a binder; the positive active substance adopts carbon fluoride or a mixture taking carbon fluoride as a main active substance; the porosity of the carbon fluoride ranges from 5% to 50%; the size of the pores of the fluorinated carbon includes one or more of macropores, mesopores, and micropores. The invention also provides a flexible package lithium fluorocarbon primary battery and a preparation method thereof, the invention preferably selects the carbon fluoride material with rich pore structure and high specific surface as the anode active substance, the special structure and the shape of the carbon fluoride reserve the space for accommodating the reaction product, limit the existing shape of the reaction product and greatly reduce the discharge expansion of the anode plate. The positive and negative electrode plate thickness mutual balance in the discharging process is realized by combining reasonable positive and negative electrode surface capacity design and electrode compaction density design.)

1. The battery positive plate is characterized by comprising a positive current collector, wherein the outer surface of the positive current collector is coated with a positive active material coating;

the positive active material coating comprises a positive active material, a conductive agent and a binder;

the mass ratio of the positive active substance to the conductive agent to the binder is as follows: (80-95), (10-2) and (10-3);

wherein, the positive active substance adopts carbon fluoride, or adopts a mixture taking carbon fluoride as a main active substance;

the porosity of the carbon fluoride ranges from 5% to 50%;

the size of the pores of the fluorinated carbon comprises one or more of macropores, mesopores and micropores;

wherein the aperture of the macropore is more than 50nm, the aperture of the mesopore is 2 nm-50 nm, and the aperture of the micropore is less than 2 nm;

the pore structure of the carbon fluoride pores comprises one or more of through holes, semi-through holes and three-dimensional through holes;

the specific surface area of the carbon fluoride is 300m²/g～3000m²/g。

2. The positive electrode sheet according to claim 1, wherein the porosity of the carbon fluoride is 5 to 30%;

the positive current collector is aluminum foil.

3. The positive electrode sheet for a battery according to claim 1, wherein the kind of the carbon fluoride includes at least one of fluorinated hard carbon, fluorinated soft carbon, fluorinated amorphous carbon, fluorinated artificial graphite, fluorinated natural graphite, fluorinated graphene, fluorinated carbon fiber, fluorinated carbon nanotube, fluorinated carbon microsphere, fluorinated activated carbon, and fluorinated carbon black;

the conductive agent comprises graphite, carbon black, activated carbon, carbon microspheres, carbon nano tubes, carbon nano fibers, graphene, silver Ag and titanium oxide TiO₂One or more of;

the binder comprises one or more of styrene-butadiene latex, sodium carboxymethylcellulose, polyacrylate, modified polyacrylate, polyacrylonitrile, polyvinylidene fluoride, modified polyvinylidene fluoride and polytetrafluoroethylene.

4. The positive electrode sheet according to claim 1, wherein the atomic ratio of F/C in the fluorinated carbon is 0.3 to 1.5.

5. The positive electrode sheet according to claim 1, wherein the mixture containing carbon fluoride as a main active material for the positive electrode active material contains, in addition to carbon fluoride, an active material comprising manganese dioxide MnO₂NiO, CuO and V₂O₅Silicon oxide SiO₂And Ag₂V₄O₁₁And the like, one or more of substances reactive with lithium;

in the mixture with carbon fluoride as the main active substance, the mass specific gravity of the carbon fluoride is more than or equal to 20% and less than 100%.

6. A flexible package lithium fluorocarbon primary battery is characterized by comprising a flexible package shell;

a battery pole group is arranged in the soft package shell;

the soft package shell is filled with non-aqueous electrolyte

The battery pole set comprises the positive pole piece according to any one of claims 1 to 5, a negative pole piece and a separator;

the positive plate adopts a positive plate with a discharge expansion rate of 20-50%;

the thickness expansion value in the positive plate discharging process is equal to the thickness reduction value in the negative plate discharging process;

the partition is positioned between the positive plate and the negative plate;

the battery pole group is prepared from a positive plate, a negative plate and a diaphragm in a winding, lamination or winding type lamination mode.

7. The flexibly packaged lithium fluorocarbon primary cell of claim 6 wherein the substrate surface of the separator comprises a functional coating of an organic binder;

the base material of the diaphragm comprises any one of Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), Polyimide (PI) and aramid;

the structural form of the diaphragm comprises the steps of coating a ceramic layer and an organic binder on one surface of a substrate of the diaphragm in a mixed manner, respectively coating the ceramic layer and the organic binder on the two surfaces of the substrate of the diaphragm in a mixed manner, and sequentially coating the ceramic layer and the organic binder layer on the surface of the substrate of the diaphragm;

wherein the organic binder comprises any one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer and polymethyl methacrylate;

the total thickness of the diaphragm ranges from 8 mu m to 50 mu m.

8. The flexibly packaged lithium fluorocarbon primary battery of claim 6 wherein the negative plate comprises a negative current collector;

the outer surface of the negative current collector is compounded with a negative active material;

the negative active material includes metallic lithium or lithium-containing alloy;

wherein, in the lithium-containing alloy, the alloy elements comprise one or more of nickel Ni, cobalt Co, manganese Mn, aluminum Al, magnesium Mg and zirconium Zr;

the flexible package shell is made of an aluminum plastic film or a stainless steel composite film;

the thickness range of the soft package shell is 60-300 μm.

9. A preparation method of a flexible package lithium fluorocarbon primary battery is characterized by comprising the following steps:

step S1, positive plate manufacturing: uniformly mixing a positive electrode active substance, a conductive agent and a binder according to a preset mass ratio, dispersing the mixture in a solvent NMP (N-methyl pyrrolidone) to prepare a positive electrode slurry, uniformly coating the positive electrode slurry on the surface of an aluminum foil serving as a positive electrode current collector, and sequentially performing the procedures of drying, rolling and shearing to obtain a positive electrode piece;

in step S1, the mass ratio among the positive electrode active material, the conductive agent, and the binder is: (80-95), (10-2) and (10-3);

step S2, negative electrode sheet production: compounding metal lithium or lithium alloy as a negative active material with current collectors such as copper and nickel, and cutting into preset specifications;

step S3, battery pole group preparation: preparing a battery pole group by cutting the positive pole piece, the diaphragm and the negative pole piece according to the preset specification in a winding, lamination or winding type lamination mode according to the design requirement;

step S4, housing packaging: putting the battery pole group into a preformed flexible package shell, sealing the shell at two sides or three sides by adopting a hot melting sealing process, and reserving one side for injecting liquid;

step S5, liquid injection and sealing: injecting electrolyte into the battery in a dry environment, and vacuumizing and sealing a battery injection port;

step S6, hot-press polymerization: applying pressure and temperature to the battery which is injected and sealed, and keeping for a preset time; then, the pressure is continuously applied under the normal temperature or the preset low temperature environment and is continued for a certain time;

step S7, aging: respectively standing for a preset time under the preset high-temperature and room-temperature environment to realize the full infiltration of the electrolyte on the electrode group;

step S8, degassing and sealing: and (4) vacuumizing and sealing the battery to realize final sealing, and finally obtaining a finished battery.

10. The method of claim 9, wherein in step S6, the predetermined time duration is 3 to 15 minutes;

in step S7, the preset time for the shelf is 5-15 days;

the preset low-temperature environment is an environment with the temperature range of-10 ℃ to 25 ℃;

the preset high-temperature environment is an environment with the temperature range of 35-70 ℃.

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a battery positive plate, a flexible package lithium fluorocarbon primary battery and a preparation method thereof.

Background

Lithium/carbon fluoride (Li/CF)_x) The battery is a solid positive electrode lithium primary battery which is a commodity firstly, is the highest in a positive electrode series due to the theoretical mass specific energy of 2180Wh/kg, has good high-temperature performance and safety performance, is high and stable in discharge platform and low in self-discharge rate, and has been greatly concerned.

The flexible package lithium fluorocarbon battery adopts the light shell, compared with a metal shell battery, the battery has obvious advantages of specific energy, flexible and variable size and excellent safety performance, has the most promising prospect, and is also the battery which has the most attention in current research.

In the discharging process of the lithium-carbon fluoride battery, the carbon fluoride as the positive active material and lithium ions generate a lithium combination reaction to generate lithium fluoride and carbon, and the product lithium fluoride and carbon cover the surface of the carbon fluoride to gradually enlarge carbon fluoride particles, so that the carbon fluoride positive plate can be greatly thickened along with the progress of the discharging process of the battery due to the reaction characteristics, and the thickness change rate usually reaches 100-200%. Since the electrodes of the battery have inevitable non-uniformity in the reaction process, the thickness variation of the positive electrode sheet at different positions is also non-uniform in the discharge process, which forms ravines and dead zones, so that partial carbon fluoride cannot fully participate in the reaction, and the utilization rate of the battery capacity is low.

In fact, lithium in the negative electrode is continuously consumed and the thickness of the lithium is continuously reduced in the discharging process, but the expansion of the positive electrode sheet and the formed gaps, folds and the like lead to the contact between the positive electrode sheet and the negative electrode sheet and the diaphragm to be poor, the distance between the positive electrode sheet and the diaphragm is increased, and finally the thickness of the battery is obviously expanded, so that the utilization rate of the capacity of the battery is reduced.

For the battery with a soft package structure, because the strength of the shell is lower, the contact of an electrode reaction interface is slightly worse than that of the battery with a metal shell, and the expansion of the anode plate cannot be effectively restrained, the non-uniformity of the thickness of the anode plate and the utilization rate of the battery capacity in the discharging process are all worse than those of the battery with the metal shell. In order to avoid adverse effects caused by deformation and thickness expansion of the flexible-package lithium fluorocarbon primary battery in the discharging process and improve the capacity utilization rate of the battery, the flexible-package battery is usually clamped and discharged by a clamp, the difficulty of battery combination is greatly increased by the method, and the application range of the lithium fluorocarbon battery is also greatly limited.

Disclosure of Invention

The invention aims to provide a battery positive plate, a flexible package lithium fluorocarbon primary battery and a preparation method thereof aiming at the technical defects in the prior art.

Therefore, the invention provides a battery positive plate, which comprises a positive current collector, wherein the outer surface of the positive current collector is coated with a positive active material coating;

the positive active material coating comprises a positive active material, a conductive agent and a binder;

the mass ratio of the positive active substance to the conductive agent to the binder is as follows: (80-95), (10-2) and (10-3);

wherein, the positive active substance adopts carbon fluoride, or adopts a mixture taking carbon fluoride as a main active substance;

the porosity of the carbon fluoride ranges from 5% to 50%;

the size of the pores of the fluorinated carbon comprises one or more of macropores, mesopores and micropores;

wherein the aperture of the macropore is more than 50nm, the aperture of the mesopore is 2 nm-50 nm, and the aperture of the micropore is less than 2 nm;

the pore structure of the carbon fluoride pores comprises one or more of through holes, semi-through holes and three-dimensional through holes;

the specific surface area of the carbon fluoride is 300m²/g～3000m²/g。

The positive current collector is aluminum foil.

Wherein the kind of the carbon fluoride comprises at least one of fluorinated hard carbon, fluorinated soft carbon, fluorinated amorphous carbon, fluorinated artificial graphite, fluorinated natural graphite, fluorinated graphene, fluorinated carbon fiber, fluorinated carbon nanotube, fluorinated carbon microsphere, fluorinated activated carbon and fluorinated carbon black;

the conductive agent comprises graphite, carbon black, activated carbon, carbon microspheres, carbon nano tubes, carbon nano fibers, graphene, silver Ag and titanium oxide TiO₂One or more of;

the binder comprises one or more of styrene-butadiene latex, sodium carboxymethylcellulose, polyacrylate, modified polyacrylate, polyacrylonitrile, polyvinylidene fluoride, modified polyvinylidene fluoride and polytetrafluoroethylene.

Wherein the F/C atomic ratio in the carbon fluoride is 0.3 to 1.5.

Wherein, for the positive electrode active material, in the mixture with carbon fluoride as the main active material, the active material in addition to the carbon fluoride can include manganese dioxide MnO₂NiO, CuO and V₂O₅Silicon oxide SiO₂And Ag₂V₄O₁₁And the like, one or more of substances reactive with lithium;

in the mixture with carbon fluoride as the main active substance, the mass specific gravity of the carbon fluoride is more than or equal to 20% and less than 100%.

In addition, the invention also provides a flexible package lithium fluorocarbon primary battery, which comprises a flexible package shell;

a battery pole group is arranged in the soft package shell;

the soft package shell is filled with non-aqueous electrolyte

The battery pole group comprises the positive pole piece, the negative pole piece and the diaphragm;

the positive plate adopts a positive plate with a discharge expansion rate of 20-50%;

the thickness expansion value in the positive plate discharging process is equal to the thickness reduction value in the negative plate discharging process;

the partition is positioned between the positive plate and the negative plate;

the battery pole group is prepared from a positive plate, a negative plate and a diaphragm in a winding, lamination or winding type lamination mode.

Wherein, the surface of the substrate of the diaphragm comprises an organic binder functional coating;

the base material of the diaphragm comprises any one of Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), Polyimide (PI) and aramid;

the structural form of the diaphragm comprises the steps of coating a ceramic layer and an organic binder on one surface of a substrate of the diaphragm in a mixed manner, respectively coating the ceramic layer and the organic binder on the two surfaces of the substrate of the diaphragm in a mixed manner, and sequentially coating the ceramic layer and the organic binder layer on the surface of the substrate of the diaphragm;

wherein the organic binder comprises any one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer and polymethyl methacrylate;

the total thickness of the diaphragm ranges from 8 mu m to 50 mu m.

Wherein the negative plate comprises a negative current collector;

the outer surface of the negative current collector is compounded with a negative active material;

the negative active material includes metallic lithium or lithium-containing alloy;

wherein, in the lithium-containing alloy, the alloy elements comprise one or more of nickel Ni, cobalt Co, manganese Mn, aluminum Al, magnesium Mg and zirconium Zr;

the flexible package shell is made of an aluminum plastic film or a stainless steel composite film;

the thickness range of the soft package shell is 60-300 μm.

In addition, the invention also provides a preparation method of the flexible package lithium fluorocarbon primary battery, which comprises the following steps:

step S1, positive plate manufacturing: uniformly mixing a positive electrode active substance, a conductive agent and a binder according to a preset mass ratio, dispersing the mixture in a solvent NMP (N-methyl pyrrolidone) to prepare a positive electrode slurry, uniformly coating the positive electrode slurry on the surface of an aluminum foil serving as a positive electrode current collector, and sequentially performing the procedures of drying, rolling and shearing to obtain a positive electrode piece;

in step S1, the mass ratio among the positive electrode active material, the conductive agent, and the binder is: (80-95), (10-2) and (10-3);

step S2, negative electrode sheet production: compounding metal lithium or lithium alloy as a negative active material with current collectors such as copper and nickel, and cutting into preset specifications;

step S3, battery pole group preparation: preparing a battery pole group by cutting the positive pole piece, the diaphragm and the negative pole piece according to the preset specification in a winding, lamination or winding type lamination mode according to the design requirement;

step S4, housing packaging: putting the battery pole group into a preformed flexible package shell, sealing the shell at two sides or three sides by adopting a hot melting sealing process, and reserving one side for injecting liquid;

step S5, liquid injection and sealing: injecting electrolyte into the battery in a dry environment, and vacuumizing and sealing a battery injection port;

step S6, hot-press polymerization: applying pressure and temperature to the battery which is injected and sealed, and keeping for a preset time; then, the pressure is continuously applied under the normal temperature or the preset low temperature environment and is continued for a certain time;

step S7, aging: respectively standing for a preset time under the preset high-temperature and room-temperature environment to realize the full infiltration of the electrolyte on the electrode group;

step S8, degassing and sealing: and (4) vacuumizing and sealing the battery to realize final sealing, and finally obtaining a finished battery.

In step S6, the preset duration is 3-15 minutes;

in step S7, the preset time for the shelf is 5-15 days;

the preset low-temperature environment is an environment with the temperature range of-10 ℃ to 25 ℃;

the preset high-temperature environment is an environment with the temperature range of 35-70 ℃.

Compared with the prior art, the flexible-package lithium fluorocarbon primary battery preferably adopts a fluorocarbon material with rich pore structure and high specific surface as a positive active substance, and the special structure and the appearance of the fluorocarbon reserve a space for accommodating reaction products, limit the existing forms of the reaction products and greatly reduce the discharge expansion of the positive plate (from 100-200% of an electrode prepared from a conventional material to 20-50%).

In addition, the invention can further combine the reasonable positive and negative electrode surface capacity design and the electrode compaction density design (the electrode surface capacity is the surface coating amount multiplied by the specific weight of the active substance multiplied by the gram capacity of the active substance), and realize that the thickness expansion value of the positive plate is the same as the thickness reduction value of the negative plate in the discharging process, namely, the thicknesses of the positive and negative plates are mutually balanced in the whole discharging process.

Meanwhile, the invention also adopts the diaphragm with the organic binder functional coating, and realizes the surface crosslinking of the anode and the diaphragm through the on-site thermal polymerization process, so that the surface of the battery is kept flat and does not deform in the discharging process, and the electrode and the diaphragm have good interface contact in the discharging process, thereby reducing the polarization of the battery and improving the capacity utilization rate of the active material.

In addition, the flexible-package lithium fluorocarbon primary battery provided by the invention adopts the flexible-package light shell, fully exerts the characteristic of high specific energy of the lithium fluorocarbon battery, does not expand or deform in the discharging process, does not need to adopt a high-strength shell and a clamp for limitation in the using process, greatly reduces the difficulty of combined application, and widens the application market and the application field of the lithium fluorocarbon battery. The method provided by the invention is simple and feasible, can be used for large-scale expanded production, and has good application prospect.

Drawings

Fig. 1a is a schematic diagram of a battery electrode set in a flexibly-packaged lithium fluorocarbon primary battery according to an embodiment of the present invention, in which the internal structure is shown before discharging;

fig. 1b is a schematic diagram of a battery electrode set in a flexibly-packaged lithium fluorocarbon primary battery according to an embodiment of the present invention, wherein the internal structure of the battery electrode set is before discharge;

FIG. 2 is a schematic flow chart of a method for preparing a flexibly packaged lithium fluorocarbon primary battery according to the present invention;

FIG. 3 is a graph comparing the 0.1C discharge at room temperature for the cells prepared in examples 1 and 2 of the present invention and comparative example;

FIG. 4 is a photograph showing the surface state of the electrode sheet after discharge of the battery produced in the comparative example;

in the figure, 1 is a positive plate, 11 is a positive active material coating, and 12 is a positive current collector;

2 is a negative electrode sheet, 22 is a composite layer containing a negative electrode active material, 22 is a negative electrode current collector, and 3 is a separator.

Detailed Description

In order that those skilled in the art will better understand the technical solution of the present invention, the following detailed description of the present invention is provided in conjunction with the accompanying drawings and embodiments.

The invention provides a battery positive plate, which comprises a positive current collector, wherein the outer surface of the positive current collector is coated with a positive active material coating;

the thickness expansion rate of the positive plate after discharging is 20-50%;

the positive active material coating comprises a positive active material, a conductive agent and a binder;

wherein, the positive active substance adopts carbon fluoride, or adopts a mixture taking carbon fluoride as a main active substance;

the porosity of the carbon fluoride is 5-50%, preferably 5-30%;

in the invention, the mass ratio of the positive electrode active substance, the conductive agent and the binder is as follows: (80-95), (10-2) and (10-3).

Specifically, the size of the pores of the carbon fluoride comprises one or more of macropores (the pore diameter is more than 50nm), mesopores (or called mesopores, the pore diameter is 2 nm-50 nm) and micropores (the pore diameter is less than 2 nm);

the pore structure of the carbon fluoride pores comprises one or more of through holes, semi-through holes, three-dimensional through holes and the like;

the specific surface area of the carbon fluoride is 300m²/g～3000m²/g。

It should be noted that, in the present invention, the fluorocarbon has a rich pore structure and a high specific surface area, and the porosity of the fluorocarbon is in a range of 5 to 50%, and more preferably 5 to 30%; according to the invention, the carbon fluoride material with abundant pore structures and high specific surface is preferably selected as the anode active substance, the special structure and the appearance of the carbon fluoride reserve the space capable of accommodating reaction products, the existence form of the reaction products is limited, and the discharge expansion of the anode plate is greatly reduced (from 100-200% of the electrode prepared from the conventional material to 20-50%).

In the present invention, the kind of the carbon fluoride includes at least one of fluorinated hard carbon, fluorinated soft carbon, fluorinated amorphous carbon, fluorinated artificial graphite, fluorinated natural graphite, fluorinated graphene, fluorinated carbon fiber, fluorinated carbon nanotube, fluorinated carbon microsphere, fluorinated activated carbon and fluorinated carbon black;

in particular, the carbon fluoride is preferably carbon fluoride biomass hard carbon.

Specifically, the fluorination preparation process of the carbon fluoride comprises any one of a direct fluorination method, a hydrothermal method, an electrochemical method and a plasma direct fluorination method.

In a specific implementation of the present invention, the positive current collector may be an aluminum foil.

In the present invention, the F/C atomic ratio in the fluorinated carbon is 0.3 to 1.5.

In the present invention, as for the positive electrode active material, in the mixture mainly containing carbon fluoride, the active material contained in the mixture may include manganese dioxide MnO in addition to carbon fluoride₂NiO, CuO and V₂O₅Silicon oxide SiO₂And Ag₂V₄O₁₁And the like, one or more of substances reactive with lithium;

in the mixture with carbon fluoride as the main active substance, the mass specific gravity of the carbon fluoride is more than or equal to 20% and less than 100%.

In the present invention, in the case of the present invention,in particular implementation, the conductive agent comprises graphite, carbon black, activated carbon, carbon microspheres, carbon nano tubes, carbon nano fibers, graphene, silver Ag and titanium oxide TiO₂Etc. may be used as one or more of the electrode conductive agents for lithium batteries.

In a specific implementation of the present invention, the binder includes one or more of styrene butadiene latex (SBR), sodium carboxymethylcellulose (CMC), Polyacrylate (PAA), modified polyacrylate, polyacrylonitrile, polyvinylidene fluoride (PVDF), modified polyvinylidene fluoride, Polytetrafluoroethylene (PTFE), and the like, which may be used as a binder for a lithium battery.

Based on the battery positive plate provided by the invention, the invention also provides a flexible package lithium fluorocarbon primary battery, which comprises a flexible package shell;

a battery pole group is arranged in the soft package shell;

the soft package shell is filled with non-aqueous electrolyte

The battery pole group comprises the positive pole piece, the negative pole piece and the diaphragm;

the positive plate adopts a positive plate with a discharge expansion rate of 20-50%;

in a specific implementation, the thickness expansion value during the discharge of the positive plate is preferably equal to the thickness reduction value during the discharge of the negative plate.

Wherein the partition is positioned between the positive plate and the negative plate.

It should be noted that, referring to fig. 1, the separator 3 is located between the positive plate 1 and the negative plate 2, wherein the positive plate 1 includes a positive current collector 12, and the upper and lower surfaces of the positive current collector 12 are respectively coated with a positive active material coating 11; the negative plate 2 comprises a negative current collector 22, and the upper and lower surfaces of the negative current collector 22 are respectively compounded with a compound layer 21 containing a negative active material.

In a specific implementation of the present invention, during the discharge of the battery, the thickness increase value of the positive electrode tab is the same as the thickness decrease value of the negative electrode tab, so that the thickness of the battery is hardly changed before and after the discharge. That is, the thickness expansion value of the positive electrode tab during discharge is the same as the thickness reduction value of the negative electrode tab.

It should be noted that, with respect to the technical solution of the present invention, the thickness increase value of the positive plate and the thickness decrease value of the negative plate can be the same, that is, the thickness balance is specifically realized according to a certain design principle, and the related influencing factors include the following factors:

1. and (3) positive electrode: the gram volume of the active material, the specific gravity of the active material in the positive electrode, the thickness expansion rate of the positive electrode sheet after discharge and the rolling compaction density of the positive electrode sheet;

2. negative electrode: active material gram capacity, content of metallic lithium in the negative electrode;

in the present invention, based on the existing well-known pole piece technology, a corresponding derived calculation formula can be listed:

the thickening value of the positive plate is equal to the initial thickness of the positive plate multiplied by the discharge expansion rate of the positive plate is equal to the loading capacity of the positive plate multiplied by the rolling density of the positive plate multiplied by the discharge expansion rate of the positive plate;

the thickness reduction value of the negative plate is equal to the loading capacity of the positive electrode surface multiplied by the gram capacity of the positive electrode powder multiplied by the specific weight of active substances in the positive electrode powder divided by the gram capacity of the negative electrode active substances divided by the content of metal lithium in the negative electrode divided by the negative electrode density;

wherein, the specific gravity of the active material in the positive electrode powder is the gram capacity of the negative electrode active material, the content of the metal lithium in the negative electrode, the negative electrode density, the discharge expansion rate of the positive electrode sheet, the rolling density of the positive electrode sheet, and the gram capacity of the positive electrode powder;

that is, based on the above calculation formula, when the above-mentioned relevant parameters are known, the thickness balance can be achieved by controlling the specific gravity of the active material in the positive electrode (the surface loading amount of the positive electrode powder and the initial thickness of the negative electrode do not affect the above-mentioned relationship).

As described above, in the present invention, the mass ratio of the positive electrode active material, the conductive agent, and the binder is: (80-95), (10-2) and (10-3).

In the invention, in particular, the positive plate preferably adopts a positive plate with a discharge expansion rate of 20-50%;

in the concrete implementation, the rolling density of the positive plate is preferably 1.2-1.5 g/cm³；

In the concrete implementation, the gram volume of the anode powder is preferably 500-700 mAh/g.

In a specific implementation of the present invention, the carbon fluoride is preferably a fluorocarbon biomass hard carbon.

In the invention, the structural form of the flexible-package lithium fluorocarbon primary battery comprises a square form, a special-shaped form and the like.

In the invention, the battery pole group is prepared from the positive plate, the negative plate and the diaphragm in the form of winding, lamination or winding lamination.

In the invention, based on the structural design of the positive plate, through inspection, the positive plate has a thickness expansion rate of 10-80% after discharge, and more preferably 20-50%.

In the invention, in a specific implementation, the negative plate comprises a negative current collector;

a negative active material is compounded on the outer surface of a negative current collector (for example, copper foil);

specifically, the negative active material comprises metallic lithium or lithium-containing alloy;

wherein, in the lithium-containing alloy, the alloy elements comprise one or more of nickel Ni, cobalt Co, manganese Mn, aluminum Al, magnesium Mg, zirconium Zr and the like.

The negative electrode sheet does not include a conductive agent and a binder. The compounding process of the negative plate is as follows: and pressing the metal lithium or the lithium alloy on the surface of the copper foil of the current collector by using a rolling roller and other equipment by adopting mechanical force. Because the lithium metal or the lithium alloy is very soft, and the surface of the copper foil has certain roughness, the lithium metal or the lithium alloy is microscopically anchored together by the action of external force, so that certain bonding strength is realized between the lithium metal or the lithium alloy and the copper foil. The method is the same as the conventional process of compounding the lithium metal and the copper foil, and has no particularity. This is the existing pole piece compounding technology and is not described herein again.

In the invention, in particular, the surface of the substrate of the diaphragm comprises an organic binder functional coating;

the base material of the diaphragm comprises any one of a plurality of organic films which can be used for a lithium battery, such as Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), Polyimide (PI), aramid and the like;

the structural form of the diaphragm comprises various forms of coating a ceramic layer and an organic binder on one surface of a substrate of the diaphragm in a mixed manner, respectively coating the ceramic layer and the organic binder on the two surfaces of the substrate of the diaphragm in a mixed manner, and sequentially coating the ceramic layer and the organic binder layer on the surface of the substrate of the diaphragm.

Specifically, the organic binder includes any one of polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and polymethyl methacrylate (PMMA).

In particular, the total thickness of the diaphragm ranges from 8 μm to 50 μm.

In the invention, the flexible package shell is made of an aluminum-plastic film or a stainless steel composite film;

the thickness range of the soft package shell is 60-300 μm.

Based on the technical scheme, the novel carbon fluoride material with the three-dimensional through hole multistage pore structure and the high specific surface is adopted, and the reasonable positive and negative electrode surface capacity design and the electrode compaction density design are combined, so that the thickness mutual balance of the positive and negative electrode plates in the battery discharging process is realized; meanwhile, the functional diaphragm with the surface coated with glue is adopted, the on-site hot-pressing polymerization process is applied to the lithium primary battery for the first time, the surface crosslinking of the positive plate and the diaphragm is realized, the battery surface is not deformed in the discharging process of the battery, and the good interface contact between the plate and the diaphragm is kept.

For the invention, the innovative technology realizes zero expansion of the lithium fluorocarbon battery after discharging, solves the bottleneck problems of large expansion, low capacity exertion rate, clamping discharge requirement and the like in the discharging process of the traditional carbon fluoride material and the battery, and has very high application value.

In order to prepare the flexibly packaged lithium fluorocarbon primary battery provided by the invention, referring to fig. 2, the invention also provides a preparation method of the flexibly packaged lithium fluorocarbon primary battery, which comprises the following steps:

step S1, positive plate manufacturing: uniformly mixing a positive electrode active substance, a conductive agent and a binder according to a preset mass ratio, dispersing the mixture in a solvent NMP (N-methyl pyrrolidone) to prepare a positive electrode slurry, uniformly coating the positive electrode slurry on the surface of an aluminum foil serving as a positive electrode current collector, and sequentially performing the procedures of drying, rolling and shearing to obtain a positive electrode piece;

in step S1, the mass ratio of the positive electrode active material, the conductive agent, and the binder is: (80-95), (10-2) and (10-3).

In step S1, the positive electrode sheet obtained by the preparation preferably employs a positive electrode sheet having a discharge expansion rate of 20% to 50%;

step S2, negative electrode sheet production: compounding metal lithium or lithium alloy as a negative active material with current collectors such as copper and nickel, and cutting into preset specifications;

the negative electrode sheet does not include a conductive agent and a binder. The compounding process of the negative plate is as follows: and pressing the metal lithium or the lithium alloy on the surface of the copper foil of the current collector by using a rolling roller and other equipment by adopting mechanical force. Because the lithium metal or the lithium alloy is very soft, and the surface of the copper foil has certain roughness, the lithium metal or the lithium alloy is microscopically anchored together by the action of external force, so that certain bonding strength is realized between the lithium metal or the lithium alloy and the copper foil. The method is the same as the conventional process of compounding the lithium metal and the copper foil, and has no particularity. This is the existing pole piece compounding technology and is not described herein again.

Step S3, battery pole group preparation: preparing a battery pole group by cutting the positive pole piece, the diaphragm and the negative pole piece according to the preset specification in a winding, lamination or winding type lamination mode according to the design requirement;

step S4, housing packaging: putting the battery pole group into a preformed flexible package shell, sealing the shell at two sides or three sides by adopting a hot melting sealing process, and reserving one side for injecting liquid;

step S5, liquid injection and sealing: injecting electrolyte into the battery in a dry environment, and vacuumizing and sealing a battery injection port;

step S6, hot-press polymerization: applying pressure and temperature to the battery after the liquid injection and sealing for a preset time (e.g., 5 minutes); then, the mixture is transferred to normal temperature (for example, 10-30 ℃) or preset low-temperature environment (-10 ℃ -25 ℃) to continue to apply pressure for a certain time;

step S7, aging: standing for a preset time (for example, 7 days) at a preset high temperature (35-70 ℃) and a room temperature environment (for example, 10-30 ℃) respectively to realize the full infiltration of the electrolyte to the electrode group;

step S8, degassing and sealing: and (4) vacuumizing and sealing the battery to realize final sealing, and finally obtaining a finished battery.

In step S6, the preset duration is 3-15 minutes;

in step S7, the predetermined time period for the resting is 5-15 days.

In order to more clearly understand the technical solution of the present invention, the technical solution of the present invention is described below by specific examples.