Detailed Description
The following description is presented to enable any person skilled in the art to make and use the present disclosure, and is provided in the context of a particular application and its requirements. Various local modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the present disclosure is not to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims.
The technical solution of the present invention will be described in detail with reference to the following examples.
Fig. 1 is a schematic structural diagram of a cell structure according to an embodiment of the present application.
An embodiment of the present application provides a cell structure, as shown in fig. 1, the cell structure includes: the single-layer positive plate 110 comprises a three-dimensional porous metal current collector, positive slurry can be embedded into pores of the metal current collector, and the thickness of the single-layer positive plate 110 is 2-100 mm; the single-layer negative electrode sheet 130 is made of foam carbon, and the thickness of the single-layer negative electrode sheet 130 is 1-50 mm; and the ceramic diaphragm 120 is positioned between the single-layer positive plate 110 and the single-layer negative plate 130, and has a thickness of 0.05-0.5 mm.
The traditional battery core is formed by winding or laminating a plurality of layers of positive plates and negative plates with the thickness level of microns, the production process is complex, dozens of key control points of the process exist, and the requirements on the production process and the production equipment of the battery core are extremely high. And this application embodiment the electricity core structure only includes the positive plate of one deck millimeter rank and the negative plate of one deck millimeter rank, separate by the ceramic diaphragm of one deck millimeter rank between positive plate and the negative plate, this kind of individual layer electricity core structure not only simple process, also can improve electric core security and monomer capacity simultaneously.
Referring to fig. 1, the single-layer positive electrode sheet 110 uses a three-dimensional porous metal current collector, the positive electrode slurry is filled in pores of the metal current collector, and the positive electrode can adsorb electrolyte through capillary action. Because the positive active material is filled in the current collector, compared with the conventional positive plate in which the positive active material is coated on the surface of the current collector, the route of an electronic channel can be reduced, the polarization of a charge-discharge process caused by an ultra-thick electrode is avoided, and the power characteristic of a battery core is ensured. Meanwhile, the heat generated in the charge and discharge process of the positive active material can be taken away by the metal due to the heat conductivity of the metal, so that the temperature rise in the battery cell is reduced.
In some embodiments of the present application, the three-dimensional porous metal is aluminum foam with a porosity of 50% to 90%. Porosity is the proportion of the apparent volume of the particulate material to the total volume of the material within the pores. In some embodiments of the present application, the porosity should be as high as possible to accommodate more positive active material and increase battery capacity while ensuring that the physical strength of the metal current collector is sufficient.
In some embodiments of the present application, the aluminum foam has a thickness of 2 to 100 millimeters. The thickness of the foamed aluminum can be designed according to the required thickness of the cell.
In some embodiments of the present application, the positive electrode slurry has a viscosity of 5000-. The viscosity of the positive electrode slurry cannot be too high, otherwise the positive electrode slurry is difficult to fill in the pores of the metal current collector; the viscosity of the positive electrode slurry cannot be too low, or it easily flows out of the pores of the metal current collector. The positive electrode slurry is prepared by a conventional method, and is not described in detail herein.
In some embodiments of the present application, the positive electrode slurry includes a positive electrode active material such as, for example, lithium iron phosphate or lithium nickel cobalt manganese oxide.
In some embodiments of the present application, the positive electrode paste may further include auxiliary materials such as a solvent, a binder, and a conductive agent.
In some embodiments of the present application, the porosity of the single-layer positive electrode sheet 110 is 10% to 40%. The single-layer positive plate 110 is obtained by filling the metal current collector with positive slurry, and the porosity of the single-layer positive plate 110 cannot be too low, otherwise, the capacity of the single-layer positive plate 110 for adsorbing electrolyte is reduced, and the porosity of the single-layer positive plate 110 cannot be too high, otherwise, the proportion of the positive active material in the single-layer positive plate 110 is reduced.
In some embodiments of the present application, a ceramic coating or an aramid coating may be further coated on the surface of the single-layer positive electrode sheet 110 by using a gravure coating technology, wherein the thickness of the coating is 2-3um, so as to improve the high temperature resistance and safety of the electric core.
With reference to fig. 1, in the single-layer negative electrode sheet 130 of the embodiment of the present application, the inert-treated carbon foam is used, and compared with the conventional negative electrode sheet surface coated with the negative electrode slurry, the preparation of the negative electrode slurry is not required, so that the production process is simplified, and on the other hand, compared with the conventional negative electrode in which lithium ions are embedded between the multiple layers of negative electrode sheets, the micropores on the carbon foam can directly adsorb the lithium ions, thereby improving the first charge-discharge efficiency of the battery cell.
And the surface of the active part of the foam carbon is subjected to inert treatment, so that lithium dendrite can be prevented from being separated out on the surface of the foam carbon in the charging process of the battery cell.
The foam carbon has the characteristics of small density, high strength, easy processing and the like, and good physical and chemical properties of electric conduction, heat conduction and the like, and is very suitable for being used as an electrode material.
In some embodiments of the present application, the carbon foam has a porosity of 50% to 90%. In some embodiments of the present application, the porosity should be as high as possible to accommodate more lithium ions and increase battery capacity while ensuring that the carbon foam has sufficient physical strength.
In some embodiments of the present application, the carbon foam has a density of 0.18 to 0.9g/cm3. The lower the density of the carbon foam, the lighter the cell weight for the same size.
In some embodiments of the present application, the carbon foam has a pore diameter of 0.01 to 10 microns and an average pore diameter of 0.5 to 2 microns. The diameter of the micropores is related to the reversibility of lithium metal in the charging and discharging process, and the diameter of the micropores which is too small is not beneficial to ensuring the reversibility of the charging and discharging process of deposited lithium metal, thereby causing the reduction of the cycle life.
In some embodiments of the present application, the carbon foam has a thickness of 1 to 50 millimeters. The thickness of the carbon foam can be designed according to the required thickness of the cell.
In some embodiments of the present application, the negative electrode tab position reserved on the carbon foam is subjected to copper plating treatment so as to weld the negative electrode tab, and therefore, the connection portion of the carbon foam and the tab further comprises a copper plating layer.
In some embodiments of the present application, the ceramic diaphragm 120 has a thickness of 0.05-0.5 mm. The thickness of the ceramic membrane 120 may be designed according to the desired cell thickness. The ceramic diaphragm 120 has high mechanical strength, can effectively prevent short circuit inside the pole piece, and reduces self-discharge of the battery cell.
In some embodiments of the present application, the ceramic membrane 120 includes a microporous structure, the pore size of the micropores is between 10 nm and 100nm, the surface of the ceramic membrane 120 is further subjected to a glue coating process, the thickness of the glue layer is 2-3um, the glue layer is mainly water-based PVDF, and the porosity of the ceramic membrane 120 is between 40% and 60%.
In some embodiments of the present application, the ceramic diaphragm 120 may be designed with a self-closed hole pattern for avoiding cell short circuit at high temperature.
The application provides a pair of electricity core structure adopts individual layer positive plate, diaphragm, individual layer negative plate structure, can simplify electric core production technology and control element, and then improves electric core production efficiency, and reduction in production cost uses the individual layer positive plate of tribit porous metal preparation, and the individual layer negative plate of foam carbon preparation and the ceramic diaphragm of millimeter level thickness can improve electric core monomer capacity, improves electric core security performance, reduces electric core self discharge.
The application also provides a lithium battery, which comprises the battery cell structure.
An embodiment of the present application further provides a method for manufacturing a battery cell structure, including: manufacturing a single-layer positive plate, wherein the single-layer positive plate comprises a three-dimensional porous metal current collector, positive slurry can be embedded into pores of the metal current collector, and the thickness of the positive plate is 2-100 mm; embedding positive electrode slurry into pores of the metal current collector; performing inert treatment on the surface of the active part of the carbon foam to form a single-layer negative plate, wherein the thickness of the single-layer negative plate is 1-50 mm; and assembling the single-layer positive plate, the single-layer negative plate and the ceramic diaphragm into a battery cell, wherein the diaphragm is positioned between the single-layer positive plate and the single-layer negative plate, and the thickness of the diaphragm is 0.05-0.5 mm.
The single-layer positive plate uses a three-dimensional porous metal current collector, the positive slurry is filled in the pores of the metal current collector, and the positive electrode can adsorb electrolyte through capillary action. Because the positive active material is filled in the current collector, compared with the conventional positive plate in which the positive active material is coated on the surface of the current collector, the route of an electronic channel can be reduced, the polarization of a charge-discharge process caused by an ultra-thick electrode is avoided, and the power characteristic of a battery core is ensured. Meanwhile, the heat generated in the charge and discharge process of the positive active material can be taken away by the metal due to the heat conductivity of the metal, so that the temperature rise in the battery cell is reduced.
In some embodiments of the present application, the three-dimensional porous metal is aluminum foam with a porosity of 50% to 90%. Porosity is the proportion of the apparent volume of the particulate material to the total volume of the material within the pores. In some embodiments of the present application, the porosity should be as high as possible to accommodate more positive active material and increase battery capacity while ensuring that the physical strength of the metal current collector is sufficient.
In some embodiments of the present application, the aluminum foam has a thickness of 2 to 100 millimeters. The thickness of the foamed aluminum can be designed according to the required thickness of the cell.
In some embodiments of the present application, after selecting a suitable metal current collector material, a cutting die may be further used to cut the metal current collector material to a desired size.
In some embodiments of the present application, the positive electrode slurry has a viscosity of 5000-. The viscosity of the positive electrode slurry cannot be too high, otherwise the positive electrode slurry is difficult to fill in the pores of the metal current collector; the viscosity of the positive electrode slurry cannot be too low, or it easily flows out of the pores of the metal current collector. The positive electrode slurry is prepared by a conventional method, and is not described in detail herein.
In some embodiments of the present application, the positive electrode slurry includes a positive electrode active material such as, for example, lithium iron phosphate or lithium nickel cobalt manganese oxide.
In some embodiments of the present application, the positive electrode paste may further include auxiliary materials such as a solvent, a binder, and a conductive agent.
In some embodiments of the present application, the method of embedding the positive electrode slurry into the pores of the metal current collector is a soaking slip process. Specifically, the metal current collector is immersed in the positive electrode slurry, and the positive electrode slurry is taken out after being embedded into the pores of the metal current collector. Compared with the process of coating the positive slurry on the surface of the current collector in the conventional positive plate, the soaking and slurry hanging process is simpler and is easy to implement.
In some embodiments of the present application, the metal current collector is immersed in the positive electrode slurry for a time of 5 to 30 minutes.
In some embodiments of the present application, to ensure that the inside of the metal current collector is filled with the positive electrode slurry, the immersion of the metal current collector into the positive electrode slurry may be repeated 3 to 5 times.
It should be noted that, the current collector structure needs to be ensured not to deform in the soaking and slurry hanging process, and the phenomenon that the size of the slurry hanging back pole plate is different from the design size due to the deformation of the current collector is prevented.
In some embodiments of the present application, cold/hot press shaping may also be performed on the positive current collector after filling the positive slurry to achieve the target thickness and meet the design porosity.
In some embodiments of the present application, the single-layer positive electrode sheet has a porosity of 10% to 40%. The single-layer positive plate is obtained by filling the metal current collector with positive slurry, the porosity of the single-layer positive plate cannot be too low, otherwise, the capacity of the single-layer positive plate for adsorbing electrolyte can be reduced, the porosity of the single-layer positive plate cannot be too high, and otherwise, the occupation ratio of the positive active material in the single-layer positive plate can be reduced.
In some embodiments of the present application, a ceramic coating or an aramid coating may be further coated on the surface of the single-layer positive plate by using a gravure coating technology, and the coating thickness is 2-3um, so as to improve the high temperature resistance and safety of the electric core.
In some embodiments of the present application, the carbon foam has a porosity of 50% to 90%. In some embodiments of the present application, the porosity should be as high as possible to accommodate more lithium ions and increase battery capacity while ensuring that the carbon foam has sufficient physical strength.
In some embodiments of the present application, the carbon foam has a density of 0.18 to 0.9g/cm 3. The lower the density of the carbon foam, the lighter the cell weight for the same size.
In some embodiments of the present application, the carbon foam has a pore diameter of 0.01 to 10 microns and an average pore diameter of 0.5 to 2 microns. The diameter of the micropores is related to the reversibility of lithium metal in the charging and discharging process, and the diameter of the micropores which is too small is not beneficial to ensuring the reversibility of the charging and discharging process of deposited lithium metal, thereby causing the reduction of the cycle life.
In some embodiments of the present application, the carbon foam has a thickness of 1 to 50 millimeters. The thickness of the carbon foam can be designed according to the required thickness of the cell.
In some embodiments of the present application, the inert treatment comprises surface coating. Specifically, a ceramic coating or an aramid coating is mainly coated by using a gravure coating technology, and the thickness of the coating is 2-3 um. And the surface of the active part of the foam carbon is subjected to inert treatment, so that lithium dendrite can be prevented from being separated out on the surface of the foam carbon in the charging process of the battery cell.
In some embodiments of the present application, the method of making further comprises: and carrying out copper plating treatment on the negative electrode lug part on the foam carbon to improve the weldability.
The single-layer negative plate is directly made of the foam carbon subjected to inert treatment, and compared with the conventional negative plate coated with the negative slurry on the surface, the single-layer negative plate does not need to prepare the negative slurry, so that the production process is simplified. The foam carbon has the characteristics of small density, high strength, easy processing and the like, and good physical and chemical properties of electric conduction, heat conduction and the like, and is very suitable for being used as an electrode material.
In some embodiments of the present application, the ceramic membrane has a thickness of 0.05 to 0.5 millimeters. The thickness of the ceramic separator may be designed according to a desired cell thickness. The ceramic diaphragm has high mechanical strength, can effectively prevent the short circuit in the pole piece and reduce the self-discharge of the battery cell.
In some embodiments of the present application, the ceramic diaphragm comprises a microporous structure, the pore size of the micropores is between 10 nm and 100nm, the surface of the ceramic diaphragm is further subjected to gluing treatment, the thickness of the glue layer is 2-3um, the glue layer is mainly water system PVDF, and the porosity of the ceramic diaphragm is between 40% and 60%.
In some embodiments of the present application, the ceramic diaphragm may be designed with a self-closing hole pattern for avoiding cell short circuit at higher temperatures.
The application provides a pair of electricity core structure preparation method uses individual layer positive plate, diaphragm, individual layer negative plate structure, can simplify electric core production technology and control element, and then improves electric core production efficiency, reduction in production cost, uses the individual layer positive plate of tribit porous metal preparation, and the individual layer negative plate of foam carbon preparation and the ceramic diaphragm of millimeter level thickness can improve electric core monomer capacity, improves electric core security performance, reduces electric core self discharge.
Exemplary embodiment 1
Selecting foamed aluminum as a positive current collector, wherein the porosity is 65%, the mean value of pore diameters is 2 microns, the thickness is 34 mm, the width is 140 mm, and the height is 78 mm; immersing the current collector into anode slurry with the mass ratio of lithium iron phosphate of 96.5% for 3 times, wherein each time is 30 seconds, the current collector is ensured to be filled with anode active substances, and the weight of the anode active substances is 519 g; and carrying out hot/cold pressing shaping on the current collector filled with the positive active material to obtain a single-layer positive plate, wherein the thickness of the single-layer positive plate is 30.35 mm.
The porosity of the material is 80%, and the density is 0.36g/cm3The carbon foam is used as a single-layer negative plate, the thickness of the carbon foam is 5.5 mm, the width of the carbon foam is 142 mm, the height of the carbon foam is 80 mm, the average value of the diameters of micropores is 0.5 micron, and the volume of the micropores is 50cm3(ii) a Performing inert treatment on the surface of the foam carbon; and plating copper on the single-layer negative plate electrode lug to improve the weldability of the single-layer negative plate electrode lug. Wherein the volume of the anode micropore is 50cm3The volume of lithium metal inserted into the battery cell after charging is 40cm3The anode micropore volume excess was designed to be 1.28.
And assembling the single-layer positive plate, the single-layer negative plate and a ceramic diaphragm with the thickness of 0.15 mm into a battery cell, wherein the diaphragm is positioned between the single-layer positive plate and the single-layer negative plate.
Exemplary embodiment 2
Selecting foamed aluminum as a positive current collector, wherein the porosity is 75%, the mean value of pore diameters is 2 microns, the thickness is 32 millimeters, the width is 140 millimeters, and the height is 78 millimeters; soaking the current collector in anode slurry with the mass ratio of nickel cobalt lithium manganate of 96.5% for 4 times, wherein each time is 25 seconds, and ensuring that the interior of the current collector is filled with anode active substances; and carrying out hot/cold pressing shaping on the current collector filled with the positive active material to obtain the single-layer positive plate.
The porosity was selected to be 75% and the density 0.4g/cm3The carbon foam is used as a single-layer negative plate, the thickness of the carbon foam is 6 mm, the width of the carbon foam is 142 mm, the height of the carbon foam is 80 mm, and the average value of the diameters of micropores is 1 micron; performing inert treatment on the surface of the foam carbon; and plating copper on the single-layer negative plate electrode lug to improve the weldability of the single-layer negative plate electrode lug.
And assembling the single-layer positive plate, the single-layer negative plate and a ceramic diaphragm with the thickness of 0.2 mm into a battery cell, wherein the diaphragm is positioned between the single-layer positive plate and the single-layer negative plate.
Exemplary embodiment 3
Selecting foamed aluminum as a positive current collector, wherein the porosity is 85%, the mean value of pore diameters is 2 microns, the thickness is 30 mm, the width is 140 mm, and the height is 78 mm; soaking the current collector into anode slurry with the mass ratio of lithium iron phosphate of 95.5% for 5 times, wherein each time is 20 seconds, and ensuring that the interior of the current collector is filled with anode active substances; and carrying out hot/cold pressing shaping on the current collector filled with the positive active material to obtain the single-layer positive plate.
The porosity was selected to be 70% and the density 0.44g/cm3The carbon foam is used as a single-layer negative plate, the thickness of the carbon foam is 8 mm, the width of the carbon foam is 142 mm, the height of the carbon foam is 80 mm, and the average value of the diameters of micropores is 1.5 micrometers; performing inert treatment on the surface of the foam carbon; and plating copper on the single-layer negative plate electrode lug to improve the weldability of the single-layer negative plate electrode lug.
And assembling the single-layer positive plate, the single-layer negative plate and a ceramic diaphragm with the thickness of 0.4 mm into a battery cell, wherein the diaphragm is positioned between the single-layer positive plate and the single-layer negative plate.
The utility model discloses the people has still carried out the experiment and has come the contrast this application embodiment the performance parameter of electric core structure and the performance parameter of conventional electric core structure.
Experimental group
Experimental group tests used the cells described in example embodiment 1 of the present application. Because a negative electrode active substance is not used, the first discharging coulombic efficiency of the battery cell is similar to that of lithium iron phosphate, the capacity of 1C gram of the positive electrode is about 155mAh/g (2.0-3.65V), and the discharging average voltage of the battery cell is about 3.25V. According to the parameters, the discharge capacity (2.0-3.65V) of the battery cell 1C is calculated to be 80.56Ah, the electric quantity is about 0.262kWh, and the volumetric energy density is 498 Wh/L.
Control group
The control group test uses cells made by a conventional winding process under the condition of adopting the same positive electrode system or formula and structure size. The 1C discharge capacity (2.0-3.65V) of the battery core is 61.3Ah, the electric quantity is 0.196Wh, and the volume energy density is 373 Wh/L.
As can be seen from comparison of data of the experimental group and the control group, the electrochemical performance of the battery cell in the embodiment of the present application is better than that of the battery cell manufactured by using the conventional winding process, wherein the volumetric energy density of the battery cell in the embodiment of the present application is 33% higher than that of the battery cell manufactured by using the conventional winding process.
The application provides a pair of electricity core structure uses individual layer positive plate, diaphragm, individual layer negative plate structure, can simplify electric core production technology and control factor on the one hand, and then improves electric core production efficiency, reduction in production cost, and on the other hand uses the individual layer positive plate of tribit porous metal preparation, and the individual layer negative plate of foam carbon preparation and the ceramic diaphragm of millimeter level thickness can improve electric core monomer capacity, improves electric core security performance, reduces electric core self discharge.
In conclusion, upon reading the present detailed disclosure, those skilled in the art will appreciate that the foregoing detailed disclosure can be presented by way of example only, and not limitation. Those skilled in the art will appreciate that the present application is intended to cover various reasonable variations, adaptations, and modifications of the embodiments described herein, although not explicitly described herein. Such alterations, improvements, and modifications are intended to be suggested by this disclosure, and are within the spirit and scope of the exemplary embodiments of this disclosure.
It is to be understood that the term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present.
It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be further understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, a first element in some embodiments may be termed a second element in other embodiments without departing from the teachings of the present invention. The same reference numerals or the same reference identifiers denote the same elements throughout the specification.