CN113161623B - High-safety high-specific energy low-self-discharge rechargeable battery - Google Patents

Abstract

The invention provides a rechargeable battery with high safety, high specific energy and low self-discharge. The shell of the battery is columnar, an insulating pad is arranged at the bottom of the shell, and a negative pole extending along its length is arranged in the center of the shell. The outer side is filled with a negative electrode, and a diaphragm layer is arranged on the outer side of the negative electrode. The mixture of the positive electrode and the electrolyte is filled between the diaphragm layer and the shell, and the side of the diaphragm layer facing the negative electrode is coated with porous carbon; the outer wall of the negative pole column is covered with A plurality of ring-shaped separators arranged at intervals are provided, and the ring-shaped separators are connected to the negative electrode column, and the ring-shaped separators cooperate with the diaphragm layer to guide and confine the negative electrode. The invention has moderate voltage and strong lithium ion diffusion ability, and the battery structure can reduce the shuttle effect and improve the rate performance.

Description

A rechargeable battery with high safety, high specific energy and low self-discharge

technical field

The invention relates to the field of secondary batteries, in particular to a rechargeable lithium battery with high safety, high specific energy and low self-discharge, which uses sulfur and sulfide as negative electrodes.

Background technique

The development of portable electronic devices and electric vehicles has put forward higher requirements on the specific energy, cycle performance, rate performance and safety performance of batteries. Among the candidate secondary battery systems, there are mainly lithium-ion batteries, nickel-metal hydride batteries, and the like. Among them, nickel-hydrogen batteries have lower cost, higher power characteristics, and higher safety, but lower voltage, lower energy density, and higher self-discharge rate. Traditional lithium-ion batteries generally use transition metal oxides or phosphates, such as lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, etc. The solvent is an electrolyte, and the formed lithium-ion battery has a higher voltage and thus a higher specific energy. However, a higher monomer voltage will cause the decomposition of the organic electrolyte, and many solvent molecules will be embedded in the graphite to cause its disintegration. These factors have caused the poor cycle stability of the battery; later, the researchers found that when the electrolyte When containing ethylene carbonate (EC) and other components, a relatively stable solid electrolyte interfacial layer (SEI) will be formed on the surface of the graphite negative electrode, so that the lithium-ion battery has better cycle stability, and it was commercialized in the 1990s. However, the volatile and flammable characteristics of the organic electrolyte still have a potential fire risk at a high monomer voltage, and the safety is poor. Feasible improvements include the use of non-flammable electrolytes and the use of high-capacity but moderate-voltage electrode active materials. The lithium potential of sulfur and sulfide materials is about 2V, which is significantly smaller than that of transition metal oxides or phosphates, and has a higher theoretical specific capacity. For example, the lithium storage capacity of sulfur is as high as 1672mAh/g, which is 10 times that of lithium iron phosphate. However, since sulfur and sulfide do not contain lithium, when used as a positive electrode, metal lithium must be used as a negative electrode, that is, to form a lithium-sulfur battery, and the activity of metal lithium is too high, which will also cause serious safety hazards.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to provide a rechargeable battery with high safety, high specific energy and low self-discharge, which has moderate voltage and strong lithium ion diffusion ability, and the battery structure can reduce the shuttle effect and improve the rate performance .

Based on the above purpose, the present invention provides a rechargeable battery with high safety, high specific energy and low self-discharge. The shell of the battery is cylindrical, an insulating pad is arranged at the bottom of the shell, and a negative pole extending along its length direction is arranged in the center of the shell. The outside of the negative column is filled with a negative pole, and a diaphragm layer is arranged outside the negative pole, and a mixture of a positive electrode and an electrolyte is filled between the diaphragm layer and the casing, and the side of the diaphragm layer facing the negative pole is coated with porous carbon;

The outer wall of the negative pole column is covered with a plurality of annular layer separators arranged at intervals, the annular layer separators are connected to the negative pole column, and the annular layer separators cooperate with the diaphragm layer to guide the negative electrode and limited area.

Preferably, both the shell and the negative pole are cylindrical, and the material is at least one selected from aluminum, steel, copper, nickel, zinc, and graphite.

Preferably, the radial dimension of the negative pole column is 1/20-1/5 of the radial dimension inside the housing, and the radial dimension of the negative pole pole is not less than 1 mm.

Preferably, the material of the annular layer separator is at least one of aluminum, steel, copper, nickel, zinc and graphite.

Preferably, the annular layer separator is evenly distributed along the length direction of the negative pole, the outer diameter of the annular layer separator is 1/10~1/5 of the inner diameter of the shell; the thickness of the annular layer separator is 0.1~ 0.6mm.

Preferably, the negative electrode includes an active material, a binder and a conductive agent.

Preferably, the active material is selected from at least one of sulfur, iron sulfide, cobalt sulfide, nickel sulfide, molybdenum sulfide, tungsten sulfide, and sulfurized polyacrylonitrile;

The binder is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, fluorine rubber, carboxymethyl cellulose, polyacrylic acid, and polyvinyl alcohol;

The conductive agent is selected from at least one of activated carbon, ordered mesoporous carbon, acetylene black, graphene, and carbon nanotubes.

Preferably, the separator layer is selected from at least one of polypropylene, polyethylene, glass fiber paper, and polyvinylidene fluoride;

The porous carbon is selected from at least one of activated carbon, ordered mesoporous carbon, acetylene black, graphene, and carbon nanotubes.

Preferably, the positive electrode includes an active material and a conductive agent;

The active material is selected from at least one of lithium iron phosphate, lithium cobaltate, lithium manganate, and lithium nickel manganese cobaltate.

As preferably, the electrolyte includes lithium salts, solvents and additives;

Wherein, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bistrifluoromethanesulfonylimide, lithium bisoxalate borate, lithium nitrate, and lithium sulfate;

The solvent is at least one selected from water, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,3-dioxolane, and ethylene glycol dimethyl ether.

Compared with prior art, the beneficial effect of the present invention is:

The present invention uses sulfur and sulfide as the negative electrode material, matches with the positive electrode of the oxide-based lithium-ion battery, avoids the use of high-cost copper foil and aluminum foil current collectors and winding processes, and obtains a columnar rechargeable battery with moderate voltage; in addition, for the battery system There may be disadvantages such as shuttle effect and poor rate performance. An annular layer separator and a diaphragm coated with porous carbon are set up to achieve the functions of diversion and confinement; and the positive electrode is set in a mixed state with the electrolyte to realize Higher lithium ion diffusion capacity, so as to achieve high specific energy and high power characteristics.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application and not to limit the present application.

Fig. 1 is a structural schematic diagram of a rechargeable battery in an embodiment of the present invention;

Fig. 2 is the second schematic diagram of the structure of the rechargeable battery in the embodiment of the present invention.

Among them, 1. Negative pole; 2. Negative pole; 3. Annular layer separator; 4. Porous carbon; 5. Diaphragm layer; 6. Electrolyte; 7. Positive pole; pad.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

This embodiment provides a rechargeable battery with high safety, high specific energy and low self-discharge. The shell of the battery is cylindrical, and an insulating pad is arranged at the bottom of the shell. The outer side of the negative electrode is filled with a negative electrode, and a diaphragm layer is arranged on the outer side of the negative electrode. The mixture of the positive electrode and the electrolyte is filled between the diaphragm layer and the shell, and the side of the diaphragm layer facing the negative electrode is coated with porous carbon;

The outer wall of the negative pole column is covered with a plurality of annular layer separators arranged at intervals, the annular layer separators are connected to the negative pole column, and the annular layer separators cooperate with the diaphragm layer to guide the negative electrode and limited area.

As a preferred embodiment, both the casing and the negative pole are cylindrical, and the material is at least one selected from aluminum, steel, copper, nickel, zinc, and graphite.

As a preferred implementation manner, the radial dimension of the negative pole is 1/20-1/5 of the radial dimension inside the housing, and the radial dimension of the negative pole is not less than 1mm.

As a preferred embodiment, the material of the annular layer separator is at least one of aluminum, steel, copper, nickel, zinc and graphite.

As a preferred embodiment, the annular layer separators are evenly distributed along the length direction of the negative pole, and the outer diameter of the annular layer separators is 1/10 to 1/5 of the inner diameter of the casing; the annular layer separators The thickness of the plate is 0.1-0.6 mm; preferably, the distance between two adjacent annular layer separators is 3-15 mm.

As a preferred embodiment, the negative electrode includes an active material, a binder and a conductive agent.

As a preferred embodiment, the active material is selected from at least one of sulfur, iron sulfide, cobalt sulfide, nickel sulfide, molybdenum sulfide, tungsten sulfide, and sulfurized polyacrylonitrile;

The binder is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, fluorine rubber, carboxymethyl cellulose, polyacrylic acid, and polyvinyl alcohol;

The conductive agent is selected from at least one of activated carbon, ordered mesoporous carbon, acetylene black, graphene, and carbon nanotubes.

As a preferred embodiment, the separator layer is selected from at least one of polypropylene, polyethylene, glass fiber paper, and polyvinylidene fluoride;

The porous carbon is selected from at least one of activated carbon, ordered mesoporous carbon, acetylene black, graphene, and carbon nanotubes.

As a preferred embodiment, the positive electrode includes an active material and a conductive agent;

The active material is selected from at least one of lithium iron phosphate, lithium cobaltate, lithium manganate, and lithium nickel manganese cobaltate.

As a preferred embodiment, the electrolyte includes lithium salts, solvents and additives;

Wherein, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bistrifluoromethanesulfonylimide, lithium bisoxalate borate, lithium nitrate, and lithium sulfate;

The solvent is at least one selected from water, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,3-dioxolane, and ethylene glycol dimethyl ether.

Below, the present invention is further described in conjunction with detailed example:

Embodiment one:

A rechargeable battery with high safety, high specific energy and low self-discharge, the cross-sectional structure of the battery is shown in Figure 1, and the longitudinal section structure is shown in Figure 2. The standard 18650 cylindrical steel shell is used as the shell 8, and the bottom of the shell 8 is provided with a rubber insulating pad 10; the aluminum negative pole 1 is placed in the center, the length of the negative pole is 68 mm, and the diameter is 3 mm; along the axial direction of the negative pole 5 aluminum ring-shaped separators 3 are set on the outside of the negative pole 1 and are connected with it. The distance between adjacent ring-shaped separators 3 is about 9 mm; the inner diameter of the ring-shaped separators 3 It is 3 mm, the outer diameter is 12 mm, and the thickness is 0.2 mm. The sulfur/active activated carbon composite material filled between the outer annular layer separators 3 of the negative electrode column 1 is the negative electrode 2, the mass ratio of sulfur to activated carbon is 70:30, and the polyvinylidene fluoride containing 2% mass fraction is used as the bond agent, with acetylene black containing 8% by mass as the conductive agent, compacted layer by layer, and formed a cylindrical negative electrode 2 after drying. A separator layer 5 made of porous polypropylene is wrapped around the outside of the cylindrical negative electrode 2 , and the separator layer 5 is coated with an activated carbon layer 4 towards the inside. The mixture of the positive electrode 7 and the electrolyte 6 is filled between the diaphragm layer 5 and the shell 8, and the mass ratio of the two is 90:10; the positive electrode 7 is a mixture of lithium iron phosphate and acetylene black, and the mass ratio of the two is 80:20; The composition of solution 6 is a solution of 1,3-dioxolane and ethylene glycol dimethyl ether (volume ratio 1:1) dissolved with 1 mole per liter of lithium bistrifluoromethanesulfonimide. The specific energy of the battery is 40 Wh/kg, the self-discharge rate is less than 1% per month, and it has high rate performance, cycle performance and safety performance.

Embodiment two:

The standard AA-shaped cylindrical aluminum shell is used as the shell 8, and the bottom of the shell is provided with a rubber insulating pad; the graphite negative pole is placed in the center, the length of the negative pole is 51 mm, and the diameter is 2.5 mm; 3 sets of copper ring-shaped separators are set on the On the outside of the negative pole 1 and connected with it, five annular layer separators 3 are arranged along the axial direction of the negative pole 1, that is, the distance between adjacent annular layer separators 3 is about 8 mm; The inner diameter of the layer separator 3 is 3 mm, the outer diameter is 12 mm, and the thickness is 0.15 mm. The iron sulfide/acetylene black/carbon nanotube composite material is filled between the outer annular layer separators 3 of the negative pole column 1 to be the negative pole 2, and the mass ratio of the three is 70:28:2, so as to contain 3% mass fraction of fluorine Rubber is used as a binder, and acetylene black containing 7% by mass is used as a conductive agent, which is compacted layer by layer and dried to form a cylindrical negative electrode 2 . A porous polypropylene/polyethylene composite separator layer 5 is wrapped around the outside of the cylindrical negative electrode 2, and the separator layer 5 is coated with an acetylene black layer 4 towards the inside. The mixture of the positive electrode 7 and the electrolyte 6 is filled between the diaphragm layer 5 and the shell 8, and the mass ratio of the two is 95:5; the positive electrode 7 is a mixture of lithium cobaltate and acetylene black, and the mass ratio of the two is 85:15; The composition of solution 6 is a solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate (volume ratio 1:1:1) dissolved with 1 mole per liter of lithium hexafluorophosphate. The specific energy of the battery is 60 Wh/kg, the self-discharge rate is lower than 0.8% per month, and it has high rate performance, cycle performance and safety performance.

Embodiment three:

A standard AAA-type cylindrical steel shell is used as the shell 8, and a rubber insulating pad 10 is provided at the bottom of the shell; a copper negative pole 1 is placed in the center, and the length of the negative pole 1 is 45 mm, and the diameter is 1.5 mm; a copper annular layer separator is set 3 are set on the outside of the negative pole 1 and connected with it, and three annular layer separators 3 are arranged along the axial direction of the negative pole 1, that is, the distance between adjacent annular layer separators 3 is about 11 mm ; The inner diameter of the annular layer separator 3 is 1.5 mm, the outer diameter is 5 mm, and the thickness is 0.15 mm. The titanium sulfide/acetylene black composite material is filled between the outer annular layer separators 3 of the negative electrode column 1 to be the negative electrode 2, the mass ratio of the two is 85:15, and the polytetrafluoroethylene containing 2% by mass fraction is used as the bond agent, with graphene containing 1% by mass as the conductive agent, compacted layer by layer, and formed a cylindrical negative electrode 2 after drying. A separator layer 5 made of porous polyvinylidene fluoride is wrapped around the outside of the cylindrical negative electrode 2 , and the separator layer 5 is coated with a graphene layer 4 towards the inside. The mixture of the positive electrode 7 and the electrolyte 6 is filled between the separator layer 5 and the shell 8, and the mass ratio of the two is 92:8; the positive electrode 7 is a mixture of lithium nickel manganese cobaltate (NCM111) and carbon nanotubes, and the mass ratio of the two is 99:1; the composition of electrolyte 6 is a solution of ethylene carbonate, propylene carbonate and dimethyl carbonate (volume ratio 1:1:1) dissolved with 1 mole per liter of lithium perchlorate. The specific energy of the battery is 55 Wh/kg, the self-discharge rate is less than 0.6% per month, and it has high rate performance, cycle performance and safety performance.

Embodiment four:

A cylindrical stainless steel shell with a diameter of 20 mm and a height of 15 mm is the shell 8, and the bottom of the shell is provided with a rubber insulating pad 10; an aluminum negative pole 1 is placed in the center, and the length of the negative pole 1 is 18 mm, and the diameter is 1 mm; The ring-shaped separator 3 is set on the outside of the negative pole 1 and is connected with it. Two annular separators are arranged along the axial direction of the negative pole 1, that is, the space between adjacent annular separators 3 The spacing is about 5 mm; the inner diameter of the annular layer separator 3 is 1 mm, the outer diameter is 12 mm, and the thickness is 0.1 mm. The sulfur/ordered mesoporous carbon/graphene composite material filled between the outer annular layer separators 3 of the negative pole 1 is the negative pole 2, and the mass ratio of the three is 65:30:5, with 3% mass fraction of Polyacrylic acid is used as a binder, and graphene containing 2% by mass is used as a conductive agent, which is compacted layer by layer and dried to form a cylindrical negative electrode 2 . A separator layer 5 made of porous polypropylene/polyethylene composite material is wrapped around the outside of the cylindrical negative electrode 2, and the separator layer 5 is coated with an activated carbon layer 4 towards the inside. The mixture of the positive electrode 7 and the electrolyte 6 is filled between the separator layer 5 and the shell 8, and the mass ratio of the two is 80:20; the positive electrode 7 is a mixture of lithium nickel manganese cobaltate (NCM811) and graphene, and the mass ratio of the two is 95:5; the composition of electrolyte solution 6 is 1,3-dioxolane and ethylene glycol dimethyl ether dissolved with 1 mole per liter of lithium bistrifluoromethanesulfonimide and 0.1 mole per liter of lithium nitrate (volume ratio of 1:1) solution. The specific energy of the battery is 90 Wh/kg, the self-discharge rate is less than 1.5% per month, and it has high rate performance, cycle performance and safety performance.

Embodiment five:

A cylindrical stainless steel shell with a diameter of 21 mm and a height of 70 mm is the shell 8, and the bottom of the shell is provided with a rubber insulating pad 10; a nickel negative pole 1 is placed in the center, and the length of the negative pole 1 is 72 mm, and the diameter is 3 mm; The ring-shaped separators 3 are set on the outside of the negative pole 1 and are connected with it. Five annular separators are arranged along the axial direction of the negative pole 1, that is, the space between adjacent annular separators 3 The spacing is about 11 millimeters; the inner diameter of the annular layer separator 3 is 3 millimeters, the outer diameter is 15 millimeters, and the thickness is 0.2 millimeters. Molybdenum sulfide/acetylene black/graphene composite material is filled between the outer annular layer separators 3 of the negative pole column 1 to be the negative pole 2, and the mass ratio of the three is 75:20:5, with polyethylene containing 5% by mass fraction Alcohol is used as a binder, and graphene containing 1% by mass is used as a conductive agent, which is compacted layer by layer and dried to form a cylindrical negative electrode 2 . A separator layer 5 made of glass fiber paper is wrapped on the outside of the cylindrical negative electrode 2 , and the separator layer 5 is coated with a graphene layer 4 toward the inside. The mixture of the positive electrode 7 and the electrolyte 6 is filled between the diaphragm layer 5 and the shell 8, and the mass ratio of the two is 75:25; the positive electrode 7 is a mixture of lithium manganate and acetylene black, and the mass ratio of the two is 85:15; The composition of liquid 6 is an aqueous solution in which 21 mol/kg of lithium bistrifluoromethanesulfonimide is dissolved. The specific energy of the battery is 65 Wh/kg, the self-discharge rate is less than 1% per month, and it has high rate performance, cycle performance and safety performance.

In summary, the present invention uses sulfur and sulfide as the negative electrode material to match the positive electrode of the oxide-based lithium-ion battery, avoiding the use of high-cost copper foil and aluminum foil current collectors and winding processes, and obtaining a columnar rechargeable battery with moderate voltage; in addition, for The battery system may have disadvantages such as shuttle effect and poor rate performance. An annular layer separator and a separator coated with porous carbon are set up to achieve the functions of diversion and confinement; and the positive electrode is set to be mixed with the electrolyte. State, to achieve a higher lithium ion diffusion capacity, so as to achieve high specific energy, high power characteristics.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations to the present invention. Under the circumstances, within the scope of the present invention, the above embodiments can be changed, modified, replaced and modified. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still belong to the present invention. within the scope of the technical program.

Claims (8)

1. The high-safety high-specific energy low-self-discharge rechargeable battery is characterized in that a shell is columnar, an insulating pad is arranged at the bottom of the shell, a negative pole column extending along the length direction of the shell is arranged in the center of the shell, a negative pole is filled in the outer side of the negative pole column, a diaphragm layer is arranged in the outer side of the negative pole, a mixture of a positive pole and electrolyte is filled between the diaphragm layer and the shell, and porous carbon is coated on one side of the diaphragm layer, which faces the negative pole;

the outer wall of the negative pole column is sleeved with a plurality of annular layer clapboards which are arranged at intervals, the annular layer clapboards are communicated with the negative pole column, and the annular layer clapboards are matched with the diaphragm layer to guide and limit the negative pole;

the negative electrode comprises an active material, a binder and a conductive agent; the active substance is at least one selected from sulfur, ferric sulfide, cobalt sulfide, nickel sulfide, molybdenum sulfide, tungsten sulfide and polyacrylonitrile sulfide;

the binder is at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, fluororubber, carboxymethyl cellulose, polyacrylic acid and polyvinyl alcohol;

the conductive agent is at least one selected from activated carbon, ordered mesoporous carbon, acetylene black, graphene and carbon nanotubes, and the electrolyte comprises lithium salt, a solvent and an additive;

wherein the lithium salt is at least one selected from lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bistrifluoromethane sulfonyl imide, lithium bisoxalato borate, lithium nitrate and lithium sulfate.

2. The high-safety high-specific energy low-self-discharge rechargeable battery according to claim 1, wherein the outer shell and the negative electrode column are cylindrical, and are made of at least one material selected from the group consisting of aluminum, steel, copper, nickel, zinc and graphite.

3. The high-safety high-specific energy low-self-discharge rechargeable battery according to claim 1, wherein the radial dimension of the negative electrode post is 1/20-1/5 of the radial dimension of the inner side of the casing, and the radial dimension of the negative electrode post is not less than 1mm.

4. The high-safety high-specific energy low-self-discharge rechargeable battery according to claim 1, wherein the annular layer separator is made of at least one of aluminum, steel, copper, nickel, zinc and graphite.

5. The high-safety high-specific energy low-self-discharge rechargeable battery according to claim 1, wherein the annular layer separators are uniformly distributed along the length direction of the negative electrode column, and the outer diameter of the annular layer separators is 1/10-1/5 of the inner diameter of the shell; the thickness of the annular layer separator is 0.1-0.6 mm.

6. The high-safety high-specific energy low-self-discharge rechargeable battery according to claim 1, wherein said separator layer is at least one selected from the group consisting of polypropylene, polyethylene, fiberglass paper, polyvinylidene fluoride;

the porous carbon is at least one selected from activated carbon, ordered mesoporous carbon, acetylene black, graphene and carbon nano tubes.

7. The high-safety high-specific energy low self-discharge rechargeable battery according to claim 1, wherein said positive electrode comprises an active material and a conductive agent;

the active material is at least one selected from lithium iron phosphate, lithium cobaltate, lithium manganate and lithium nickel manganese cobaltate.

8. The high-safety high-specific energy low self-discharge rechargeable battery according to claim 1,

the solvent is at least one selected from water, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1, 3-dioxolane and ethylene glycol dimethyl ether.