CN111009688B - Novel adjustable SOC symmetrical battery and preparation method thereof - Google Patents

Novel adjustable SOC symmetrical battery and preparation method thereof Download PDF

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CN111009688B
CN111009688B CN201911102958.0A CN201911102958A CN111009688B CN 111009688 B CN111009688 B CN 111009688B CN 201911102958 A CN201911102958 A CN 201911102958A CN 111009688 B CN111009688 B CN 111009688B
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electrode
counter electrode
electrolyte
working
working electrode
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CN111009688A (en
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许晓雄
刘冀鹏
张永龙
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JIANGXI GANFENG LITHIUM CO Ltd
Zhejiang Funlithium New Energy Tech Co Ltd
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JIANGXI GANFENG LITHIUM CO Ltd
Zhejiang Funlithium New Energy Tech Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/44—Fibrous material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Electrochemistry (AREA)
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Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a novel adjustable SOC symmetrical battery and a preparation method thereof, wherein the symmetrical battery comprises a working electrode, a counter electrode, an isolating membrane, an electrolyte and a packaging shell, and the working electrode, the counter electrode, the isolating membrane and the electrolyte are packaged in the packaging shell; the working electrode is two like electrodes, and one side of the working electrode is provided with a first tab; the counter electrode is a metal lithium sheet, one side of the counter electrode is provided with a second lug, and the first lug and the second lug are oppositely arranged; at least one layer of isolating film is arranged on two side faces of each working electrode, and at least one layer of isolating film is arranged on two side faces of each counter electrode. The SOC of the working electrode can be adjusted in real time according to actual needs, and the preparation method can eliminate the performance reduction caused by pole piece damage, pole piece resistance increase and the like, so that the impedance performance of the anode and cathode materials of the lithium battery to be tested under different SOCs can be more accurately and efficiently evaluated, and more comprehensive basic evaluation data can be obtained.

Description

Novel adjustable SOC symmetrical battery and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a novel adjustable SOC symmetrical battery and a preparation method thereof.
Background
The battery is one of the most important electrochemical energy storage technologies at present, and generally comprises a positive (cathode) electrode, a negative (anode) electrode, an electrolyte, a diaphragm, a shell accessory and the like. In order to obtain higher electromotive force, the conventional battery technology adopts an asymmetric design, i.e., a positive (cathode) electrode and a negative (anode) electrode adopt different electrode materials, such as a lithium ion battery, a lead-acid battery, a nickel-hydrogen battery, an alkali-manganese battery and the like.
Lithium ion batteries have recently gained market favor and developed rapidly due to high energy density, long cycle life and little environmental pollution during the manufacturing process. At present, new methods and new means for mechanism analysis, material evaluation and system verification in the lithium ion battery research and development process are continuously emerging, and a symmetric battery is an important means for evaluating material impedance and provides data support for material type selection.
The symmetrical battery mainly comprises two same electrodes, is used for alternating current impedance method (EIS) test to research the internal resistance of the battery, and has the characteristics of high precision and high sensitivity. It is possible to separate different impedances in the system while avoiding influence on the electrodes and other circuit elements. The symmetric battery needs to be in an activated state when testing the impedance of a pole piece, the pole piece to be tested needs to be detached from a finished battery in the existing manufacturing method, and then the same pole piece is selected to be assembled into the symmetric battery, so that the damage to the pole piece in the process is large, the influence on the performance of the pole piece is large, and the efficiency is low.
Therefore, it is necessary to develop a new symmetrical battery to evaluate the impedance of the positive and negative electrode materials of the lithium battery more accurately and efficiently.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a novel adjustable SOC symmetrical battery, which can adjust the SOC of a working electrode in real time, so that the impedance performance of a positive electrode material and a negative electrode material of a lithium battery to be tested under different SOCs can be more accurately and more efficiently evaluated, and more comprehensive basic evaluation data can be obtained.
The second objective of the present invention is to provide a method for manufacturing a novel adjustable SOC symmetric battery, which can eliminate the pole piece damage caused by disassembling the pole piece from the finished battery in the traditional symmetric battery manufacturing process and the performance degradation such as the pole piece resistance increase caused by poor environmental control.
In order to achieve the first object, the invention provides the following technical scheme:
a novel adjustable SOC symmetrical battery comprises a working electrode, a counter electrode, an isolating membrane, electrolyte and a packaging shell, wherein the working electrode, the counter electrode, the isolating membrane and the electrolyte are packaged in the packaging shell; the device is characterized in that the working electrodes are two isotropic electrodes, and one side of each working electrode is provided with a first tab; the counter electrode is a metal lithium sheet, a second lug is arranged on one side of the counter electrode, and the first lug and the second lug are oppositely arranged; at least one layer of isolating film is arranged on the two side surfaces of each working electrode, and at least one layer of isolating film is arranged on the two side surfaces of each counter electrode;
when the electrolyte is a liquid electrolyte, the liquid electrolyte is filled among the working electrode, the counter electrode and the isolating membrane, and the isolating membrane is a diaphragm for the lithium ion battery;
when the electrolyte is a composite electrolyte composed of a liquid electrolyte and a solid electrolyte, the isolating membrane is a solid electrolyte membrane made of the solid electrolyte, and the liquid electrolyte is filled among the working electrode, the counter electrode and the isolating membrane;
when the electrolyte is a solid electrolyte, the separator is a solid electrolyte membrane made of the solid electrolyte.
By adopting the technical scheme, when the symmetrical battery is used, the two working electrodes are connected in parallel through the external circuit and then connected in series with the counter electrode, and then the symmetrical battery which is connected in series is charged and discharged, so that the two working electrodes finally reach the target SOC state, and the purpose of adjusting the SOC of the working electrodes in real time is realized, thereby more accurately and more efficiently evaluating the impedance performance of the anode and cathode materials of the lithium battery to be tested under different SOC, and more comprehensive basic evaluation data can be obtained.
When the adopted electrolyte is liquid electrolyte, the isolating membrane of the symmetrical battery is a diaphragm for the lithium ion battery, and the isolating membrane respectively separates two working electrodes and the pair of electrodes to play a role in preventing short circuit. When the adopted electrolyte is a composite electrolyte formed by a liquid electrolyte and a solid electrolyte or a single solid electrolyte, the isolating membrane of the symmetrical battery is made of the solid electrolyte, and can play a role in ion conduction while playing a role in isolation. The symmetrical batteries manufactured under the two conditions can ensure the normal test and evaluation functions and simultaneously minimize the volume, thereby effectively improving the utilization efficiency of materials.
In addition, the counter electrode adopts the metal lithium sheet, the specific capacity of the metal lithium sheet is high, and the weight and the volume of the symmetrical battery can be reduced in the system. If other active materials such as ternary positive electrodes, lithium iron phosphate, lithium titanate and the like are used, the weight and the volume of the symmetrical battery are increased due to low specific capacity, and the design and the manufacture of the battery are not facilitated. Therefore, the application selects a metal lithium sheet as the counter electrode.
Further, the packaging shell is made of an aluminum plastic film.
By adopting the technical scheme, the aluminum plastic film has good plasticity, and can better coat the working electrode, the counter electrode, the isolating film and the electrolyte to form a closed working environment. In addition, the method has multiple obtaining ways and can better meet the production requirement of the symmetrical battery.
Further, the liquid electrolyte is prepared by dissolving lithium salt in an organic solvent, and the solid electrolyte is a mixture of one or more of oxide solid electrolyte, sulfide solid electrolyte and nitride solid electrolyte.
Further, the lithium salt is LiClO 4 、LiAsF 6 、LiBF 4 、LiPF 6 、LiCF 3 SO 3 、LiTFSI、LiC(CF 3 SO 2 ) 3 And LiBOB.
Further, the organic solvent is one or a mixture of dimethyl carbonate, diethyl carbonate, ethylene glycol dimethyl ether, tetrahydrofuran, ethylene carbonate and propylene carbonate.
Further, the oxide-type solid electrolyte is a mixture of one or more of a garnet-type solid electrolyte material, a NASICON-type solid electrolyte material, a LISICON-type solid electrolyte material, and a perovskite-type solid electrolyte material.
The garnet solid electrolyte specifically comprises: li 7 A 3 B 2 O 2 Wherein A is one or more of La, ca, sr, ba and K, and B is one or more of Zr, ta, nb and Hf.
The NASICON type solid electrolyte is specifically as follows: li 1+x A x B 2+x (PO 4 ) 3 Wherein x is 0.0-0.5, A is one or more of Al, Y, ga, cr, in, fe, se and La, and B is Ti, ge, ta and ZrSn, fe, V, metal hafnium Hf.
The LISICON-type solid electrolyte specifically comprises: li 4 A(BO 4 ) 4 Wherein A is one or more of Zr, cr and Sn, and B is one or more of Si, S and P.
The perovskite type solid electrolyte is specifically: li 3x A 2/3-x BO 3 Wherein x is 0.0-0.5, A is one or more of La, al, mg, fe and Ta, and B is one or more of Ti, nb, sr and Pr.
Further, the sulfide-type solid electrolyte is crystalline or amorphous Li 2 S-P 2 S 5 Crystalline form of Li 4 MS 4 Crystalline form of Li 0 NP 2 S 2 、Li 2 S、Li 3 PS 4 、Li 3 P(S x O -x ) 4 and microcrystalline Li 2 S-P 2 S 5 -a mixture of one or more of LiX; wherein M is selected from one or more of Si, ge and Sn, N is selected from one or more of Si, ge and Sn, X is selected from one or more of Cl, br and I, and X is more than 0 and less than 1.
Further, the nitride-type solid electrolyte is Li 3 One or a mixture of two of N and LiPON.
By adopting the technical scheme, the liquid electrolyte prepared by dissolving the lithium salt in the organic solvent can provide a good conduction medium for the ion conduction of the symmetrical battery on one hand, and can supplement a certain amount of lithium ions for the symmetrical battery on the other hand, so that the influence on the performance of the symmetrical battery due to the generation of lithium dendrites is reduced. Wherein the lithium salt disclosed above has good ionic conductivity and electrochemical stability when dissolved in the above organic solvent, wherein LiPF is added 6 The most excellent performance is obtained when the polycarbonate is dissolved in dimethyl carbonate, and therefore, the most preferable is the one.
In addition, the oxide solid electrolytes, the sulfide solid electrolytes and the nitride solid electrolytes disclosed above are common solid electrolytes, and in the present application, all the currently used solid electrolytes can be replaced, so that the application range is wide, and the method can be popularized and used.
Further, when the electrolyte is a liquid electrolyte, the isolating membrane is a modified PE membrane.
Further, the modified PE film is formed by extrusion and rolling of the following components in parts by weight: 30-40 parts of metallocene polyethylene, 30-40 parts of general high-density polyethylene, 1-3 parts of ethylene propylene diene monomer, 1-2 parts of silicone and 3-5 parts of glass fiber.
By adopting the technical scheme, the modified PE film utilizes the high toughness of the metallocene polyethylene, and is used together with general high-density polyethylene and ethylene propylene diene monomer according to the weight part ratio, so that the modified PE film has good toughness and tensile property. In addition, the silicone is a solid lubricant, on one hand, the silicone can promote all components to be fully mixed and improve the processing and forming effects of the modified PE film, on the other hand, the silicone can reduce the influence on the structural strength of two polypropylene materials and ethylene propylene diene monomer, and the prepared modified PE film has excellent mechanical strength by virtue of the reinforcement of the glass fiber. The modified PE film prepared by the method can effectively reduce the possibility that the modified PE film is pierced by lithium dendrites, and further improves the safety performance of a symmetrical battery.
In order to achieve the second object, the invention provides the following technical scheme:
a preparation method of a novel adjustable SOC symmetrical battery comprises the following steps when the electrolyte is a liquid electrolyte or a composite electrolyte composed of the liquid electrolyte and a solid electrolyte:
(1) preparation of working electrode
According to the preparation method of the lithium battery positive plate or negative plate to be detected, two isotropic electrodes are prepared as working electrodes mainly through the processes of slurry mixing, coating, drying, rolling and cutting, and a first tab is welded on one side of each of the two working electrodes;
(2) preparation of counter electrode
Selecting a proper metal lithium sheet, and tightly connecting a second tab on one side of the metal lithium sheet by adopting a mechanical kneading method;
(3) preparation of packaging case
Cutting the aluminum-plastic film according to the required size, and punching the aluminum-plastic film into a packaging shell with an accommodating cavity by adopting a punching die;
(4) preparation of isolation bags
The isolation film is a diaphragm or a solid electrolyte film for the lithium ion battery, and is cut according to the required size to be made into an isolation bag with three closed sides and one open side, wherein the working electrode corresponds to a first isolation bag made of three layers of isolation films, and the counter electrode corresponds to a second isolation bag made of two layers of isolation films;
(5) and assembling the components
Two working electrodes are respectively arranged in two bag cavities of a first isolation bag, and a counter electrode is arranged in a bag cavity of a second isolation bag, so that the two working electrodes and the counter electrode are opposite to each other left and right and are embedded into an accommodating cavity of a packaging shell together; the two first pole lugs are positioned on one side of the opening of the first isolation bag and are arranged on two opposite sides of the opening at intervals, and the second pole lug is positioned on one side of the opening of the second isolation bag and is arranged opposite to the two first pole lugs;
(6) and packaging the same
Adding liquid electrolyte into the accommodating cavity of the packaging shell in the step (5), so that the electrolyte is fully filled among the isolating film, the working electrode and the counter electrode, and finally packaging and sealing;
(7) initial charging and discharging
Connecting two working electrodes in parallel through an external circuit and then connecting the working electrodes in series with a counter electrode, and carrying out primary charge and discharge on the symmetrical batteries which are connected in series; if the working electrode is a positive electrode, charging is carried out firstly, and if the working electrode is a negative electrode, discharging is carried out firstly;
(8) degassing, and removing gas
Degassing and packaging the symmetrical battery subjected to primary charging and discharging in a vacuum state;
(9) adjusting SOC
And (4) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery is obtained after the two working electrodes reach the target SOC state.
A preparation method of a novel adjustable SOC symmetrical battery comprises the following steps when the electrolyte is a liquid electrolyte or a composite electrolyte formed by the liquid electrolyte and a solid electrolyte:
(1) preparation of working electrode
According to the preparation method of the lithium battery positive plate or negative plate to be detected, two isotropic electrodes are prepared as working electrodes mainly through the processes of slurry mixing, coating, drying, rolling and cutting, and a first tab is welded on one side of each of the two working electrodes;
(2) preparation of counter electrode
Selecting two appropriate metal lithium sheets, and tightly connecting a second tab to one side of each metal lithium sheet by adopting a mechanical kneading method;
(3) preparation of packaging shell
Cutting the aluminum-plastic film according to the required size, and punching the aluminum-plastic film into a packaging shell with an accommodating cavity by adopting a punching die;
(4) preparation of the barrier bag
The isolation film is a diaphragm or a solid electrolyte film for the lithium ion battery, and is cut according to the required size to be made into an isolation bag with three closed sides and one open side, wherein the working electrode corresponds to a first isolation bag made of three layers of isolation films, and the counter electrode corresponds to a second isolation bag made of three layers of isolation films;
(5) and assembling the same
The two working electrodes are respectively arranged in two bag cavities of a first isolation bag, and the two counter electrodes are respectively arranged in two bag cavities of a second isolation bag, so that the two working electrodes and the two counter electrodes are opposite to each other left and right and are embedded into a containing cavity of a packaging shell together; the two first tabs are positioned on one side of the opening of the first isolation bag and are arranged on two opposite sides of the opening at intervals, and the two second tabs are positioned on one side of the opening of the second isolation bag and are arranged opposite to the two first tabs;
(6) and packaging the same
Adding liquid electrolyte into the accommodating cavity of the packaging shell in the step (5), so that the electrolyte is fully filled among the isolating film, the working electrode and the counter electrode, and finally packaging and sealing;
(7) initial charging and discharging
Connecting two working electrodes in parallel through an external circuit, connecting two counter electrodes in parallel, connecting the two working electrodes in parallel and the two counter electrodes in parallel in series, and performing primary charging and discharging on the symmetrical batteries which are connected in series; if the working electrode is a positive electrode, charging is carried out firstly, and if the working electrode is a negative electrode, discharging is carried out firstly;
(8) degassing, degassing
Degassing and packaging the symmetrical battery subjected to primary charging and discharging in a vacuum state;
(9) adjusting the SOC
And (5) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery can be obtained after the two working electrodes reach the target SOC state.
A preparation method of a novel adjustable SOC symmetrical battery comprises the following steps when the electrolyte is a solid electrolyte:
(1) preparation of working electrode
According to the preparation method of the lithium battery positive plate or negative plate to be detected, two isotropic electrodes are prepared as working electrodes mainly through the processes of slurry mixing, coating, drying, rolling and cutting, and a first tab is welded on one side of each of the two working electrodes;
(2) preparation of counter electrode
Selecting two proper metal lithium sheets, and tightly connecting a second tab to one side of each metal lithium sheet by adopting a mechanical kneading method;
(3) preparation of packaging shell
Cutting the aluminum-plastic film according to the required size, and stamping the aluminum-plastic film into a packaging shell with an accommodating cavity (7) by adopting a stamping die;
(4) preparation of the separator
The isolating membrane is a solid electrolyte membrane, and is cut according to the required size;
(5) and assembling the same
Sequentially stacking the isolating film, the counter electrode, the isolating film, the working electrode, the isolating film, the counter electrode and the isolating film in the accommodating cavity of the packaging shell; the two first electrode lugs and the two second electrode lugs are oppositely arranged;
(6) and packaging the same
Directly packaging and sealing the packaging shell;
(7) initial charging and discharging
Two working electrodes are respectively connected in series with adjacent counter electrodes to finally form two groups of working electrode-counter electrode pairs, the two groups of working electrode-counter electrode pairs which are close to each other are connected in series through an external circuit, and the symmetrical batteries which are connected in series are subjected to primary charging and discharging; if the working electrode is a positive electrode, charging is carried out firstly, and if the working electrode is a negative electrode, discharging is carried out firstly;
(8) degassing, and removing gas
Degassing and packaging the symmetrical battery subjected to primary charging and discharging in a vacuum state;
(9) adjusting the SOC
And (4) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery is obtained after the two working electrodes reach the target SOC state.
By adopting the technical scheme, the working electrode adopts the preparation method of the traditional lithium battery positive plate and the traditional lithium battery negative plate, the pole piece damage caused by disassembling the pole piece from the finished battery in the traditional symmetrical battery manufacturing process and the performance reduction conditions such as the pole piece resistance increase caused by poor environmental control can be eliminated, and the accuracy of the performance measurement result is ensured.
In addition, the symmetrical electrode can usually generate a small amount of gas after initial charging and discharging, and the gas generated by initial charging and discharging can be effectively removed by performing degassing operation in a vacuum state, so that the excellent performance of the symmetrical battery is ensured.
When the symmetrical battery adopting the liquid electrolyte is prepared, the isolating films are respectively and correspondingly manufactured into a first isolating bag for accommodating the working electrode and a second isolating bag for accommodating the counter electrode, so that the isolating effect of the working electrode and the counter electrode is ensured, and the possibility of short circuit is effectively reduced. Meanwhile, the working electrode and the counter electrode are conveniently and independently packaged, and the working electrode and the counter electrode are conveniently and quickly stacked and mounted in a packaging shell.
When a symmetrical battery which adopts a solid electrolyte or a symmetrical battery which simultaneously has a liquid electrolyte and a solid electrolyte is prepared, the isolating membrane is directly the solid electrolyte, the solid electrolyte is used as an ion conduction medium of a working electrode and a counter electrode on one hand, and the two are isolated on the other hand, so that the possibility of short circuit of the symmetrical battery is reduced. The liquid electrolyte in the latter can fill the gap between the working electrode and the counter electrode, and effectively reduce the interface resistance. In addition, because the content of the liquid electrolyte in the two symmetrical batteries is obviously reduced, even no liquid electrolyte exists, lithium dendrite formed at the counter electrode can be effectively reduced, and in order to ensure that the counter electrode can release sufficient lithium ions, the counter electrode is set to be two sheets when the all-solid-state symmetrical battery or the mixed solid-liquid symmetrical battery is prepared.
In conclusion, the invention has the following beneficial effects:
1. according to the symmetrical battery, the SOC of the working electrode can be adjusted in real time according to actual needs, so that the impedance performance of the anode and cathode materials of the lithium battery to be tested under different SOCs can be evaluated more accurately and more efficiently, and more comprehensive basic evaluation data can be obtained;
2. in the symmetrical battery, when the electrolyte is a liquid electrolyte, the self-made modified PE film can effectively reduce the possibility of short circuit of the symmetrical battery, and has excellent cycle performance;
3. in the preparation method of the symmetrical battery, the working electrode is obtained by adopting the traditional preparation method of the positive plate and the negative plate of the lithium battery, the condition that the performance of the battery is reduced due to the damage of the pole pieces, the increase of the resistance of the pole pieces and the like can be eliminated, and the accuracy of a performance measurement result is ensured.
Drawings
FIG. 1 is a schematic diagram of the external structure of a symmetrical battery of example 1 a;
FIG. 2 is a schematic diagram of the internal structure of a cross section of a symmetrical battery of example 1 a;
FIG. 3 is a schematic diagram of the internal structure of the symmetrical battery of example 1a after the initial charge;
FIG. 4 is a schematic diagram showing the external structure of the symmetrical battery of example 2 a;
FIG. 5 is a schematic diagram of the internal structure of a symmetrical cell cross-section of example 2 a;
FIG. 6 is a schematic diagram showing the external structure of the symmetrical battery of example 3 a;
FIG. 7 is a schematic diagram of the internal structure of a cross section of a symmetrical battery of example 3 a;
fig. 8 is a schematic view of the internal structure of a symmetrical cell longitudinal section of example 3 a.
In the figure, 1, a working electrode; 2. a counter electrode; 3. an isolation film; 4. packaging the shell; 5. a first tab; 6. a second tab; 7. an accommodating chamber; 8. a terminal external connection portion; 9. and (6) gluing the pole lugs.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The materials and reagents of the purchasing manufacturers and/or models which are not noted in the application can be purchased from the market and are not the technical key points of the application, so the purchasing manufacturers do not disclose further.
1. Examples of the embodiments
Example 1a
A novel adjustable SOC symmetrical battery is shown in figures 1 and 2 and comprises a working electrode 1, a counter electrode 2, a separation film 3, electrolyte and a packaging shell 4, wherein the working electrode 1, the counter electrode 2, the separation film 3 and the electrolyte are packaged in the packaging shell 4.
The working electrode 1 is two like electrodes, and one side of the working electrode 1 is provided with a first tab 5; the counter electrode 2 is a metal lithium sheet, one side of the counter electrode 2 is provided with a second electrode lug 6, the first electrode lug 5 and the second electrode lug 6 are oppositely arranged and are respectively connected with a terminal external part 8, and the terminal external part 8 is fixedly penetrated out of the outer side of the packaging shell 4. Wherein, the two first tabs 5 are respectively connected with different terminal external parts 8.
Two side surfaces of each working electrode 1 are provided with a layer of isolating film 3, and two side surfaces of the counter electrode 2 are provided with a layer of isolating film 3. The electrolyte is a liquid electrolyte, the liquid electrolyte is filled among the working electrode 1, the counter electrode 2 and the isolating membrane 3, and the isolating membrane 3 is a diaphragm for the lithium ion battery.
A preparation method of a novel adjustable SOC symmetrical battery comprises the following steps:
(1) preparation of working electrode 1
The working electrode 1 in this embodiment is an example of a positive plate, and the specific preparation process is as follows:
a1, sequentially weighing LiCoO according to a weight ratio of 80 2 Adding N-methyl pyrrolidone into carbon black and polyvinylidene fluoride, and uniformly mixing to obtain positive active slurry with solid content of 60%;
b1, taking an aluminum foil with the thickness of 8 microns as a positive electrode current collector, coating the positive electrode active slurry prepared in the step a on two side surfaces of the aluminum foil, evaporating N-methyl pyrrolidone to dryness at 90 ℃, then feeding the N-methyl pyrrolidone into a roller press for rolling, and cutting according to the required size to obtain a positive electrode sheet, namely the working electrode 1;
taking two working electrodes 1 prepared in the above way, and respectively welding a first tab 5 on the same side of the two working electrodes 1.
(2) Preparation of counter electrode 2
A proper lithium metal sheet is selected, and a second lug 6 is tightly connected to one side of the lithium metal sheet by a mechanical kneading method.
(3) Preparation of the packaging shell 4
And cutting the aluminum-plastic film according to the required size, and stamping the aluminum-plastic film into a packaging shell 4 with an accommodating cavity 7 by adopting a stamping die.
(4) Preparation of isolation bags
The isolating film 3 is a diaphragm for the lithium ion battery, the isolating film 3 is cut according to the required size, an isolating bag with three sealed sides and one open side is manufactured through heat sealing, wherein the working electrode corresponds to a first isolating bag manufactured by heat sealing of the three layers of isolating films 3, and the counter electrode 2 corresponds to a second isolating bag manufactured by heat sealing of the two layers of isolating films 3.
The isolating membrane 3 is a modified PE membrane and comprises the following components in parts by weight: 35 parts of metallocene polyethylene (polyethylene 200, from exxonmobil), 35 parts of general high-density polyethylene (polyethylene 4404, from exxonmobil), 2 parts of ethylene propylene diene monomer, 2 parts of silicone and 5 parts of glass fiber. The preparation process comprises the following steps:
a2, putting metallocene polyethylene, general high-density polyethylene, ethylene propylene diene monomer rubber and silicone into a stirrer, and premixing for 5min to obtain a premix;
b2, putting the premix into a double-screw extruder, controlling the temperature of the front section to be 170 ℃, the temperature of the middle section to be 200 ℃ and the temperature of the rear section to be 190 ℃, adding glass fiber into the rear section, controlling the extrusion temperature to be 205 ℃, and extruding and cooling to obtain an extruded material;
c2, feeding the extruded material into an extruder for drawing, wherein the drawing tension is 20kg/cm 2 And controlling the draft ratio to be 2.
(5) And assembling the same
Two working electrodes 1 are respectively arranged in two bag cavities of a first isolation bag, and a counter electrode 2 is arranged in a bag cavity of a second isolation bag, so that the two working electrodes 1 and the counter electrode 2 are opposite left and right and are embedded into an accommodating cavity 7 of a packaging shell 4 together; the two first tabs 5 are positioned on one side of the opening of the first isolation bag and are arranged on two opposite sides of the opening at intervals, and the second tab 6 is positioned on one side of the opening of the second isolation bag and is arranged opposite to the two first tabs 5.
(6) And packaging the same
Adding liquid electrolyte into the accommodating cavity of the packaging shell in the step (5), so that the liquid electrolyte is fully filled among the isolating film 3, the working electrode 1 and the counter electrode 2, and finally packaging and sealing;
wherein the liquid electrolyte is LiPF 6 Prepared by dissolving in dimethyl carbonate and LiPF 6 The concentration of (B) was 12.5wt%. The temperature of the end socket during packaging and sealing can be controlled at 150-190 deg.C, the processing time is 2-5s, and the temperature is preferably set at 170 deg.C and 4s in this embodiment.
(7) Initial charging
Two working electrodes are connected in parallel through an external circuit (constant current charging and discharging, the current range is 0.05C-0.5C, the current of the embodiment is preferably 0.2C), and then are connected in series with the counter electrode 2, the symmetrical battery which is connected in series is charged for the first time, and the internal structure of the symmetrical battery after charging is shown in fig. 3.
(8) Degassing, and removing gas
The symmetrical battery after the initial charge and discharge is degassed and packaged in a vacuum state (the vacuum degree is 10-500Pa, and the embodiment is preferably 300 Pa).
(9) Adjusting SOC
And (4) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery is obtained after the two working electrodes reach the target SOC state.
Examples 1b to 1c
Examples 1b to 1c the amounts of the components of the separator 3 (modified PE film) were adjusted on the basis of the methods of the examples. See table one below for specific adjustments:
TABLE A table of composition and dosage parameters for the barrier films of examples 1a-1c
Example 1a Example 1b Example 1c
Metallocene polyethylene 35 30 40
General purpose high density polyethylene 35 40 30
Ethylene propylene diene monomer 2 1 3
Silicone 2 1 2
Glass fiber 4 3 5
Example 1d
In this embodiment, based on the method of embodiment 1a, the isolation film 3 is a PE film with model number Grion 0011V, which is available from hangzhou environmental protection technologies ltd.
Example 1e
This example was modified as follows based on the method of example 1 a.
In step (1), the working electrode 1 in this embodiment is exemplified by a negative plate, and the specific preparation process is as follows:
A. sequentially weighing graphite, acetylene black and sodium carboxymethylcellulose according to a weight ratio of 85;
B. and (b) taking a copper foil with the thickness of 8 microns as a negative current collector, coating the negative active slurry prepared in the step (a) on two side surfaces of the copper foil, and evaporating deionized water to dryness at 80 ℃ to obtain a negative plate, namely the working electrode 1.
And (7) carrying out primary discharge on the symmetrical batteries which are connected in series.
Examples 1f to 1j
Examples 1f-1j the composition and content of the liquid electrolyte were adjusted based on the method of example 1 a. See table two below for specific adjustments:
TABLE two liquid electrolyte parameter tables for examples a and f-j
Figure BDA0002270403210000141
Example 2a
A novel adjustable SOC symmetrical battery is shown in figures 4 and 5 and comprises a working electrode 1, a counter electrode 2, a separation film 3, electrolyte and a packaging shell 4, wherein the working electrode, the counter electrode 2, the separation film 3 and the electrolyte are packaged in the packaging shell 4.
The working electrode 1 is two like electrodes, and one side of the working electrode 1 is provided with a first tab 5; the counter electrode 2 is two lithium metal sheets, one side of the counter electrode 2 is provided with a second electrode lug 6, the first electrode lug 5 and the second electrode lug 6 are oppositely arranged and are respectively connected with an external terminal part 8, and the external terminal part 8 is fixedly penetrated out of the outer side of the packaging shell 4. Wherein, the two first tabs 5 are respectively connected with different terminal external parts 8.
Two side surfaces of each working electrode 1 are provided with a layer of isolating film 3, and two side surfaces of the counter electrode 2 are provided with a layer of isolating film 3. The electrolyte is a composite electrolyte composed of a liquid electrolyte and a solid electrolyte, the isolation membrane 3 is a solid electrolyte membrane made of the solid electrolyte, and the liquid electrolyte is filled among the working electrode 1, the counter electrode 2 and the isolation membrane 3 formed by the solid electrolyte.
A preparation method of a novel adjustable SOC symmetrical battery comprises the following steps:
the working electrode 1 in this embodiment is an example of a positive plate, and the specific preparation process is as follows:
a1, sequentially weighing LiCoO2, carbon black and polyvinylidene fluoride according to a weight ratio of 80;
b1, taking an aluminum foil with the thickness of 8 microns as a positive current collector, coating the positive active slurry prepared in the step a on two side surfaces of the aluminum foil, evaporating N-methylpyrrolidone to dryness at 90 ℃, then feeding the N-methylpyrrolidone into a roller press for rolling, and cutting according to the required size to obtain a positive plate, namely a working electrode 1;
taking two working electrodes 1 prepared in the above way, and respectively welding a first tab 5 on the same side of the two working electrodes 1.
(2) Preparation of counter electrode 2
Two suitable lithium metal sheets are selected, and a second lug 6 is tightly connected to one side of each lithium metal sheet by a mechanical kneading method.
(3) Preparation of the packaging shell 4
And cutting the aluminum-plastic film according to the required size, and stamping the aluminum-plastic film into the packaging shell 4 with the accommodating cavity 7 by adopting a stamping die.
(4) Preparation of the separator 3
The isolation film 3 is a solid electrolyte film formed by pressing solid electrolyte, and is cut according to the required size to be made into an isolation bag with three closed sides and one open side, wherein the working electrode 1 corresponds to a first isolation bag formed by pressing three layers of isolation films 3, and the counter electrode 2 corresponds to a second isolation bag formed by pressing three layers of isolation films 3. The specific preparation process of the isolation film 3 is as follows:
a2, mixing a solid electrolyte LLZO, an electrolyte polymer PVDF and an electrolyte additive DBP according to the weight ratio of 80:5:5, weighing;
b2, mixing the solid electrolyte LLZO with an electrolyte polymer PVDF to prepare a master batch;
c2, adding the master batch and electrolyte additive DBP into a double-screw extruder, and heating and mixing the master batch and the electrolyte additive DBP by the double-screw extruder to obtain electrolyte master batch;
d2, feeding the electrolyte masterbatch into an extruder for drafting, wherein the tension of the drafting is 80kg/cm 2 And controlling the draft ratio to be 2.
(5) And assembling the same
Two working electrodes 1 are respectively arranged in two bag cavities of a first isolation bag, and two counter electrodes 2 are respectively arranged in two bag cavities of a second isolation bag, so that the two working electrodes 1 and the two counter electrodes 2 are opposite left and right and are embedded into an accommodating cavity 7 of a packaging shell 4 together; the two first pole lugs 5 are positioned on one side of the opening of the first isolation bag and are arranged on two opposite sides of the opening at intervals, and the two second pole lugs 6 are positioned on one side of the opening of the second isolation bag and are arranged opposite to the two first pole lugs 5;
(6) and packaging the same
Adding liquid electrolyte into the accommodating cavity of the packaging shell in the step (5), so that the liquid electrolyte is fully filled among the isolating film 3, the working electrode 1 and the counter electrode 2, and finally packaging and sealing;
wherein the liquid electrolyte is LiPF 6 Prepared by dissolving in dimethyl carbonate and LiPF 6 The concentration of (2) was 12.5wt%. The temperature of the end socket during packaging and sealing can be controlled at 150-190 deg.C, the processing time is 2-5s, and the temperature is preferably set at 180 deg.C and 2s in this embodiment.
(7) Initial charging
Two working electrodes are connected in parallel through an external circuit (constant current charging and discharging, the current range is 0.05C-0.5C, the current of the embodiment is preferably 0.5C), and then are connected in series with a counter electrode 2, and the symmetrical batteries which are connected in series are subjected to primary charging.
(8) Degassing, and removing gas
The symmetrical cell after the initial charge and discharge is degassed and sealed in a vacuum state (the vacuum degree is 10-500Pa, the preferred embodiment is 150 Pa).
(9) Adjusting the SOC
And (4) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery is obtained after the two working electrodes reach the target SOC state.
Examples 2b to 2f
Examples 2b-2f the composition and content of the liquid electrolyte and the composition and content of the solid electrolyte were adjusted on the basis of the method of example 2 a. See table three below for specific adjustments:
TABLE TRI-TABLE EXAMPLES 2a-2g TABLE FOR ADJUSTING PARAMETERS OF ELECTROLYTE
Figure BDA0002270403210000161
Example 3a
A novel adjustable SOC symmetrical battery is shown in figures 6 and 7 and comprises a working electrode, a counter electrode 2, an isolation film 3 and a packaging shell 4, wherein the working electrode 1, the counter electrode 2 and the isolation film 3 are all packaged in the packaging shell 4.
With reference to fig. 8, the working electrode 1 is two like electrodes, and a first tab 5 is disposed on one side of the working electrode 1; the counter electrode 2 is two lithium metal sheets, one side of the counter electrode 2 is provided with a second lug 6, the first lug 5 and the second lug 6 are oppositely arranged and are respectively connected with an external terminal part 8, and the external terminal part 8 is fixedly penetrated out of the outer side of the packaging shell 4 through a lug glue 9. The two first tabs 5 are respectively connected with different terminal external connection parts 8, and the two first tabs are only schematically shown to have the same horizontal position.
Two side surfaces of each working electrode 1 are provided with a layer of isolating film 3, and two side surfaces of the counter electrode 2 are provided with a layer of isolating film 3. Wherein, the electrolyte is a solid electrolyte, the isolating membrane 3 is made of the solid electrolyte, and the liquid electrolyte is filled among the working electrode 1, the counter electrode 2 and the isolating membrane 3 formed by the solid electrolyte.
A preparation method of a novel adjustable SOC symmetrical battery comprises the following steps:
the working electrode 1 in this embodiment is an example of a positive plate, and the specific preparation process is as follows:
a1, sequentially weighing LiCoO according to a weight ratio of 80 2 Adding N-methyl pyrrolidone into carbon black and polyvinylidene fluoride, and uniformly mixing to obtain positive active slurry with solid content of 60%;
b1, taking an aluminum foil with the thickness of 8 microns as a positive current collector, coating the positive active slurry prepared in the step a on two side surfaces of the aluminum foil, evaporating N-methylpyrrolidone to dryness at 90 ℃, then feeding the N-methylpyrrolidone into a roller press for rolling, and cutting according to the required size to obtain a positive plate, namely a working electrode 1;
taking two working electrodes 1 prepared in the above way, and respectively welding a first tab 5 on the same side of the two working electrodes 1.
(2) Preparation of counter electrode 2
Two suitable lithium metal sheets are selected, and a second lug 6 is tightly connected to one side of each lithium metal sheet by a mechanical kneading method.
(3) Preparation of the packaging shell 4
And cutting the aluminum-plastic film according to the required size, and stamping the aluminum-plastic film into a packaging shell 4 with an accommodating cavity 7 by adopting a stamping die.
(4) Preparation of the separator 3
The separator 3 is a solid electrolyte membrane formed by pressing a solid electrolyte, and the separator 3 is cut according to a required size; the specific preparation process of the isolating membrane 3 comprises the following steps:
a2, mixing a solid electrolyte LLZO, an electrolyte polymer PVDF and an electrolyte additive DBP according to a weight ratio of 80:15:5, weighing;
b2, mixing the solid electrolyte LLZO with an electrolyte polymer PVDF to prepare a master batch;
c2, adding the master batch and electrolyte additive DBP into a double-screw extruder, and heating and mixing the master batch and the electrolyte additive DBP by the double-screw extruder to obtain electrolyte master batch;
d2, feeding the electrolyte masterbatch into an extruder for drafting, wherein the tension of the drafting is 80kg/cm 2 And controlling the draft ratio to be 2.
(5) And assembling the components
Sequentially stacking the isolating film 3, the counter electrode 2, the isolating film 3, the working electrode 1, the isolating film 3, the counter electrode 2 and the isolating film 3 in an accommodating cavity 7 of the packaging shell 4; the two first electrode lugs 5 and the two second electrode lugs 6 are arranged oppositely;
(6) and packaging the same
The packaging shell is directly packaged and sealed. The temperature of the end socket during packaging and sealing can be controlled at 150-190 deg.C, the processing time is 2-5s, and the temperature is preferably set at 180 deg.C and 4s in this embodiment.
(7) Initial charging
Two working electrodes 1 are respectively connected with adjacent counter electrodes 2 in series to finally form two groups of working electrode 1-counter electrode 2 pairs, the two groups of working electrode 1-counter electrode 2 pairs which are close to each other are connected in series through an external circuit (constant current charging and discharging, the current range is 0.05C-0.5C, the current of the embodiment is preferably 0.5C), and the symmetrical batteries which are connected in series are subjected to primary charging.
(8) Degassing, and removing gas
The symmetrical cell after the initial charge and discharge is degassed and sealed in a vacuum state (the vacuum degree is 10-500Pa, the preferred embodiment is 150 Pa).
(9) Adjusting the SOC
And (4) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery is obtained after the two working electrodes reach the target SOC state.
Examples 3b to 3f
Examples 3b-3f the composition and amount of the liquid electrolyte and the composition and amount of the solid electrolyte were adjusted based on the method of example 3 a. See table four below for specific adjustments:
TABLE IV TABLE OF PARAMETERS OF ELECTROLYTES IN EXAMPLES 3a-3f
Figure BDA0002270403210000191
2. Comparative example
Comparative example 1a
This comparative example is based on the method of example 1a, and the working electrode 1 is obtained by peeling directly from the finished lithium battery.
Comparative example 2a
This comparative example is based on the method of example 2a, and the working electrode 1 is obtained by stripping directly from the finished lithium battery.
Comparative example 3a
This comparative example is based on the method of example 3a, and the working electrode 1 is obtained by stripping directly from the finished lithium battery.
3. Performance verification
The symmetric cells of examples 1a-1j, 2a-2f, 3a-3f and comparative examples 1a, 2a, 3a were subjected to the following performance tests, the results of which are given in table five below.
1. Cycle life performance test experiment: under the constant current/constant voltage condition (room temperature 60 ℃) of 1C/4.2V, each battery is charged by 1C/4.2V cut-off current and discharged by 1C/3.0V cut-off, and the cycle number when the capacity retention rate is 80% or more is counted.
2. Internal resistance test experiment: the internal resistance of the invention adopts a German Zahner electrochemical workstation to carry out alternating current impedance test; the test system is a U-Buffer two-electrode system, the test frequency range is 0.01Hz-100KHz, and the amplitude is 5mV.
3. Spike passage rate test experiment: the probe diameter was 5mm as measured according to GB/T31485-2015.
Table five test results of the symmetrical batteries of examples 1a to 1j, 2a to 2f, 3a to 3f and comparative examples 1a, 2a, 3a
Figure BDA0002270403210000201
By combining the table five, the detection results of the embodiment 1a and the comparative example 1a, the detection results of the embodiment 2a and the comparative example 2a, and the detection results of the embodiment 3a and the comparative example 3a are respectively compared, so that the symmetrical battery prepared by the method can adjust the SOC of the working electrode in real time according to actual needs, has excellent specific capacity, cycle performance and safety performance, has lower internal resistance, and can eliminate the performance reduction caused by damage of the pole piece, increase of the resistance of the pole piece and the like, so that the impedance performance of the to-be-detected lithium battery anode and cathode materials under different SOCs can be more accurately and more efficiently evaluated, and more comprehensive basic evaluation data can be obtained.
Comparing the detection results of the embodiments 1a to 1e, it can be seen that the self-made modified PE film adopted by the separator of the present application can effectively reduce the possibility of the separator being pierced by lithium dendrites, thereby reducing the possibility of short circuit of the symmetrical battery, and having more excellent safety performance.
By comparing the results of the tests of examples 1a and 1f to 1j, it can be seen that the liquid electrolyte of the present application is formed of LiPF 6 When prepared by dissolving in dimethyl carbonate, the performance of the symmetrical battery prepared by the method is corresponding to that of the symmetrical batteryIs obviously superior to other liquid electrolytes, and therefore, the electrolyte is prepared by LiPF 6 The liquid electrolyte prepared by dissolving dimethyl carbonate is preferable, and example a is preferable.
By comparing the detection results of the embodiments 2a to 2f and 3a to 3f, respectively, the solid electrolyte of the present application can be properly adjusted according to the requirement of the reagent, and has wide applicability.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims (8)

1. The utility model provides a novel adjustable SOC symmetry battery, includes working electrode (1), counter electrode (2), barrier film (3), electrolyte and packaging shell (4), and working electrode (1), counter electrode (2), barrier film (3) and electrolyte encapsulation in packaging shell (4), its characterized in that:
the working electrode (1) is two isotropic electrodes, and one side of the working electrode (1) is provided with a first tab (5); the counter electrode (2) is a metal lithium sheet, a second pole lug (6) is arranged on one side of the counter electrode (2), and the first pole lug (5) and the second pole lug (6) are oppositely arranged; two side surfaces of each working electrode (1) are provided with at least one layer of the isolating film (3), and two side surfaces of the counter electrode (2) are provided with at least one layer of the isolating film (3);
when the electrolyte is a liquid electrolyte, the liquid electrolyte is filled among the working electrode (1), the counter electrode (2) and the isolating film (3), the isolating film (3) is a modified PE film for the lithium ion battery, and the modified PE film is formed by extruding and rolling the following components in parts by weight: 30-40 parts of metallocene polyethylene, 30-40 parts of general high-density polyethylene, 1-3 parts of ethylene propylene diene monomer, 1-2 parts of silicone and 3-5 parts of glass fiber; the working electrode (1) is arranged in a first isolation bag made of the isolation film (3), the counter electrode (2) is arranged in a second isolation bag made of the isolation film (3), and the working electrode (1) and the counter electrode (2) are opposite left and right and embedded into the packaging shell (4) together; the two working electrodes (1) are connected in parallel through an external circuit and then connected in series with the counter electrode (2), and finally, the symmetrical batteries which are connected in series are subjected to primary charging and discharging;
when the electrolyte is a composite electrolyte composed of a liquid electrolyte and a solid electrolyte, the isolating film (3) is a solid electrolyte film made of the solid electrolyte, the liquid electrolyte is filled among the working electrode (1), the counter electrode (2) and the isolating film (3), the working electrode (1) is arranged in a first isolating bag made of the isolating film (3), the counter electrode (2) is arranged in a second isolating bag made of the isolating film (3), and the working electrode (1) and the counter electrode (2) are oppositely arranged from left to right and are embedded into the packaging shell (4) together; the working electrode (1) and the counter electrode (2) are respectively connected in parallel through an external circuit, the working electrode (1) and the counter electrode (2) which are connected in parallel are connected in series, and finally, the symmetrical batteries which are connected in series are charged and discharged for the first time;
when the electrolyte is a solid electrolyte, the isolating membrane (3) is a solid electrolyte membrane made of the solid electrolyte, and the isolating membrane (3), the counter electrode (2), the isolating membrane (3), the working electrode (1), the isolating membrane (3), the counter electrode (2) and the isolating membrane (3) are sequentially stacked in a packaging shell (4); working electrode (1) earlier rather than adjacent counter electrode (2) are established ties and are formed working electrode (1) -counter electrode (2) to, and the working electrode (1) -counter electrode (2) that are close to each other are established ties rethread external circuit, and the symmetry battery that will establish ties at last carries out first charge-discharge.
2. The new tunable SOC symmetric battery according to claim 1, characterized in that said package housing (4) is made of aluminum plastic film.
3. The novel tunable symmetric SOC battery according to claim 1, wherein said liquid electrolyte is made by dissolving lithium salt in organic solvent, and said solid electrolyte is a mixture of one or more of oxide solid electrolyte, sulfide solid electrolyte and nitride solid electrolyte.
4. The novel tunable symmetric SOC battery of claim 3, wherein the lithium salt is LiClO 4 、LiAsF 6 、LiBF 4 、LiPF 6 、LiCF 3 SO 3 、LiTFSI、LiC(CF 3 SO 2 ) 3 And LiBOB.
5. The novel tunable SOC symmetric battery as claimed in claim 3, wherein the organic solvent is one or more selected from dimethyl carbonate, diethyl carbonate, ethylene glycol dimethyl ether, tetrahydrofuran, ethylene carbonate, and propylene carbonate.
6. The method for preparing the novel adjustable SOC symmetric battery according to claim 1, wherein when the electrolyte is a liquid electrolyte or a composite electrolyte composed of a liquid electrolyte and a solid electrolyte, the method comprises the following steps:
(1) preparation of working electrode (1)
According to the preparation method of the lithium battery positive plate or negative plate to be detected, two like-nature electrodes are prepared as working electrodes (1) mainly through the processes of slurry mixing, coating, drying, rolling and cutting, and a first tab (5) is welded on one side of each of the two working electrodes (1);
(2) preparation of counter electrode (2)
Selecting a proper metal lithium sheet, and tightly connecting a second lug (6) on one side of the metal lithium sheet by adopting a mechanical kneading method;
(3) preparation of the packaging shell (4)
Cutting the aluminum-plastic film according to the required size, and punching the aluminum-plastic film into a packaging shell (4) with an accommodating cavity (7) by adopting a punching die;
(4) preparation of isolation bags
The isolating membrane (3) is a diaphragm or a solid electrolyte membrane for the lithium ion battery, and is cut according to the required size to be made into an isolating bag with three closed sides and one open side, wherein the working electrode (1) corresponds to a first isolating bag made of three layers of isolating membranes (3), and the counter electrode (2) corresponds to a second isolating bag made of two layers of isolating membranes (3);
(5) and assembling the components
Two working electrodes (1) are respectively arranged in two bag cavities of a first isolation bag, and a counter electrode (2) is arranged in a bag cavity of a second isolation bag, so that the two working electrodes (1) and the counter electrode (2) are opposite left and right and are embedded into an accommodating cavity (7) of a packaging shell (4) together; the two first lugs (5) are positioned on one side of the opening of the first isolation bag and are arranged on two opposite sides of the opening at intervals, and the second lug (6) is positioned on one side of the opening of the second isolation bag and is arranged opposite to the two first lugs (5);
(6) and packaging the same
Adding liquid electrolyte into the accommodating cavity (7) of the packaging shell (4) in the step (5), so that the electrolyte is fully filled among the isolating film (3), the working electrode (1) and the counter electrode (2), and finally packaging and sealing;
(7) initial charging and discharging
Connecting two working electrodes (1) in parallel through an external circuit and then connecting the working electrodes in series with a counter electrode (2), and carrying out primary charging and discharging on the symmetrical batteries which are connected in series; wherein, if the working electrode (1) is a positive electrode, the charging is carried out firstly, and if the working electrode (1) is a negative electrode, the discharging is carried out firstly;
(8) degassing, and removing gas
Degassing and packaging the symmetrical battery subjected to primary charging and discharging in a vacuum state;
(9) adjusting the SOC
And (4) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery is obtained after the two working electrodes (1) reach the target SOC state.
7. The method for preparing the novel adjustable SOC symmetric battery according to claim 1, wherein when the electrolyte is a liquid electrolyte or a composite electrolyte composed of a liquid electrolyte and a solid electrolyte, the method comprises the following steps:
(1) preparation of working electrode (1)
According to the preparation method of the lithium battery positive plate or negative plate to be detected, two like-nature electrodes are prepared as working electrodes (1) mainly through the processes of slurry mixing, coating, drying, rolling and cutting, and a first tab (5) is welded on one side of each of the two working electrodes (1);
(2) preparation of counter electrode (2)
Selecting two proper metal lithium sheets, and tightly connecting a second lug (6) on one side of each metal lithium sheet by adopting a mechanical kneading method;
(3) preparation of the packaging shell (4)
Cutting the aluminum-plastic film according to the required size, and stamping the aluminum-plastic film into a packaging shell (4) with an accommodating cavity (7) by adopting a stamping die;
(4) preparation of isolation bags
The isolation film (3) is a diaphragm or a solid electrolyte film for the lithium ion battery, and is cut according to the required size to be made into an isolation bag with three closed sides and one open side, wherein the working electrode (1) corresponds to a first isolation bag made of the three layers of isolation films (3), and the counter electrode (2) corresponds to a second isolation bag made of the three layers of isolation films (3);
(5) and assembling the components
The two working electrodes (1) are respectively arranged in two bag cavities of a first isolation bag, and the two counter electrodes (2) are respectively arranged in two bag cavities of a second isolation bag, so that the two working electrodes (1) and the two counter electrodes (2) are opposite to each other left and right and are embedded into an accommodating cavity (7) of a packaging shell (4) together; the two first tabs (5) are positioned on one side of the opening of the first isolation bag and are arranged on two opposite sides of the opening at intervals, and the two second tabs (6) are positioned on one side of the opening of the second isolation bag and are arranged opposite to the two first tabs (5);
(6) and packaging the same
Adding liquid electrolyte into the accommodating cavity (7) of the packaging shell (4) in the step (5), so that the electrolyte is fully filled among the isolating film (3), the working electrode (1) and the counter electrode (2), and finally packaging and sealing;
(7) initial charging and discharging
Connecting two working electrodes (1) in parallel through an external circuit, connecting two counter electrodes (2) in parallel, and finally connecting the two working electrodes (1) connected in parallel and the two counter electrodes (2) connected in parallel in series, and carrying out primary charging and discharging on the symmetrical batteries connected in series; wherein, if the working electrode (1) is a positive electrode, the charging is carried out firstly, and if the working electrode (1) is a negative electrode, the discharging is carried out firstly;
(8) degassing, degassing
Degassing and packaging the symmetrical battery subjected to primary charging and discharging in a vacuum state;
(9) adjusting the SOC
And (4) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery is obtained after the two working electrodes (1) reach the target SOC state.
8. The method for preparing the novel adjustable SOC symmetric battery as claimed in claim 1, wherein when the electrolyte is a solid electrolyte, the method comprises the following steps:
(1) preparation of working electrode (1)
According to the preparation method of the lithium battery positive plate or negative plate to be detected, two homogeneous electrodes are prepared as working electrodes (1) mainly through the processes of slurry mixing, coating, drying, rolling and cutting, and a first tab (5) is welded on one side of each of the two working electrodes (1);
(2) preparation of counter electrode (2)
Selecting two proper metal lithium sheets, and tightly connecting a second lug (6) on one side of each metal lithium sheet by adopting a mechanical kneading method;
(3) preparation of the packaging shell (4)
Cutting the aluminum-plastic film according to the required size, and punching the aluminum-plastic film into a packaging shell (4) with an accommodating cavity (7) by adopting a punching die;
(4) preparation of the separator (3)
The isolating membrane (3) is a solid electrolyte membrane, and the isolating membrane (3) is cut according to the required size;
(5) and assembling the components
Sequentially stacking the isolating film (3), the counter electrode (2), the isolating film (3), the working electrode (1), the isolating film (3), the counter electrode (2) and the isolating film (3) in an accommodating cavity (7) of the packaging shell (4); wherein the two first lugs (5) and the two second lugs (6) are arranged oppositely;
(6) and packaging the same
Directly packaging and sealing the packaging shell (4);
(7) initial charging and discharging
Two working electrodes (1) are respectively connected with adjacent counter electrodes (2) in series to finally form two groups of working electrode (1) -counter electrode (2) pairs, the two groups of working electrode (1) -counter electrode (2) pairs which are close to each other are connected in series through an external circuit, and the symmetrical batteries which are connected in series are charged and discharged for the first time; wherein, if the working electrode (1) is a positive electrode, the charging is carried out firstly, and if the working electrode (1) is a negative electrode, the discharging is carried out firstly;
(8) degassing, and removing gas
Degassing and packaging the symmetrical battery subjected to primary charging and discharging in a vacuum state;
(9) adjusting the SOC
And (5) charging and discharging the symmetrical battery by adopting the method in the step (7), so that the final symmetrical battery can be obtained after the two working electrodes (1) reach the target SOC state.
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