CN110993953B - Positive plate, solid-state chemical power supply and preparation method - Google Patents

Positive plate, solid-state chemical power supply and preparation method Download PDF

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CN110993953B
CN110993953B CN201911364738.5A CN201911364738A CN110993953B CN 110993953 B CN110993953 B CN 110993953B CN 201911364738 A CN201911364738 A CN 201911364738A CN 110993953 B CN110993953 B CN 110993953B
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CN110993953A (en
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方文英
颜亮亮
李和顺
范羚羚
虞嘉菲
安仲勋
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Shanghai Aowei Technology Development 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0085—Immobilising or gelification of electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
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    • H01M2300/0091—Composites in the form of mixtures
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Abstract

The invention relates to a positive plate, a solid-state chemical power supply and a preparation method. A conductive network layer is arranged between the positive electrode material layer and the electrolyte layer of the positive electrode plate, and the conductive network layer is as follows: the conductive layer formed by preparing the conductive slurry coated on the surface of the anode material layer is formed by penetrating the electrolyte slurry coated on the conductive layer under the hierarchical capillary effect, and the electrolyte slurry is used for preparing the electrolyte layer. The positive plate of the invention takes the conductive network layer as a tie and a buffer layer for connecting the positive active material layer and the solid electrolyte layer, has a soft structure and high electronic and ionic conductivity, reduces the interface contact internal resistance between the active material and the solid electrolyte, and improves the poor physical contact between the electrode and the electrolyte caused by the volume deformation of the positive material in the charging and discharging process. In addition, the conductive network layer can be used as a protective layer to prevent side reactions and by-product transmission, thereby effectively improving the utilization rate of active substances.

Description

Positive plate, solid-state chemical power supply and preparation method
Technical Field
The invention relates to an electrode, a chemical power supply and a preparation method, in particular to a positive plate, a solid-state chemical power supply and a preparation method.
Background
The lithium ion battery has the advantages of high energy density, long cycle life, high reliability, environmental friendliness and the like, but most of lithium ion battery electrolytes are organic carbonate solvents, such as ethylene carbonate, propylene carbonate and the like, so that safety problems of liquid leakage, ignition, explosion and the like exist, and a thermal runaway phenomenon frequently occurs in recent years. The solid electrolyte adopted by the all-solid-state lithium battery cannot volatilize and is not easy to burn, so that the safety problem of the battery is expected to be fundamentally solved, and meanwhile, the all-solid-state lithium battery can further improve the energy density of the lithium battery due to the effective inhibition of lithium dendrite, so that the all-solid-state lithium battery becomes a current research hotspot.
In solid-state ionization, a solid-state electrolyte is an ionic conductor that has high ionic conductivity and at the same time blocks electron transport. Therefore, all-solid-state batteries using solid electrolytes generally have superior safety performance and higher energy density, and are ideal batteries for electric vehicles. But the performance of the material of the solid electrolyte largely determines the rate capability, the cycle stability, the safety performance, the high and low temperature performance and the service life of the battery.
Currently, the most major problems in the application of solid electrolytes are:
firstly, because the inorganic solid electrolyte is often a hard ceramic material, does not have fluidity, and has poor wettability with a lithium metal interface, it is difficult to ensure sufficient contact between active material particles and the solid electrolyte, and meanwhile, the contact interface between the solid electrolyte and the active material particles is further damaged by the volume change of the active material in the battery charging and discharging processes, so that the larger contact impedance between the solid electrolyte and the active material is caused, and the performance of the solid lithium ion battery is influenced.
Second, the good mechanical strength of solid electrolytes is generally considered to be effective in inhibiting the growth of Li dendrites, but studies have shown that Li dendrites can still follow Li dendrites7La3Zr2O12(LLZO) and Li2S–P2S5The grain boundaries of the two types of solid electrolytes grow rapidly, and internal short circuit often occurs after dozens of cycles, so that the service life of the all-solid lithium ion battery is seriously influenced. The growth mechanism of the specific lithium dendrites in the solid electrolyte is not yet determined, but the mainstream view at present is that the lithium dendrites grow rapidly because the solid electrolyte is relatively stable with lithium metal, so that the lithium metal deposited in the grain boundaries and defects is hardly consumed, which further causes the tip electric field effect to accelerate the growth of the lithium dendrites along the grain boundaries.
Third, the problem of interface stability is that some conventional organic polymer electrolytes, such as PEO, are oxidized and decomposed on the positive electrode side of high voltage, which results in increased contact resistance and deteriorated battery performance; on the other hand, the oxide solid electrolyte and the sulfide solid electrolyte undergo reductive decomposition on the negative electrode side, resulting in a decrease in the performance of the solid-state battery.
CN109994783A discloses a method for preparing an all-solid-state battery by in-situ solid-state polymerization, in which liquid small-molecule monomers infiltrated into each interface of a battery unit are directly polymerized and cured in situ by an electron beam polymerization method to generate a solid electrolyte, thereby greatly improving the compatibility of the all-solid-state battery solid-solid interface.
CN109921097A discloses an all-solid-state battery, in which at least one conversion reaction material is applied on at least one outer surface of an all-solid-state electrolyte layer to form at least one coating layer by compounding with the all-solid-state electrolyte layer; a lithium negative electrode is applied to the cladding layer to react with the cladding layer to form a solid electrolyte interfacial film. The obtained all-solid-state battery can prevent short circuit of the battery due to reduced interface resistance and inhibited dendrite formation, and improve safety performance of the battery.
The invention patents all solve the interface construction problem of the existing all-solid-state battery. Because the solid electrolyte does not have the wetting action of the liquid electrolyte, the solid particle points inside the positive electrode layer, the negative electrode layer and the electrolyte layer or the diaphragm layer of the solid battery are in contact, and gaps among the particles easily cause unsmooth ion transmission channels in a battery system, so that the solid-solid connection inside the all-solid battery becomes a difficult point for research.
Disclosure of Invention
One of the main purposes of the present invention is to solve the problem of non-ideal interface contact between the solid positive electrode material layer in the electrode sheet and the electrolyte layer, and to improve the stability of the interface.
In order to achieve the above object, the present invention provides a positive electrode sheet comprising a positive electrode material layer and an electrolyte layer,
a conductive network layer is arranged between the anode material layer and the electrolyte layer,
the conductive network layer is as follows:
the conductive layer formed by preparing the conductive slurry coated on the surface of the anode material layer is formed by penetrating the electrolyte slurry coated on the conductive layer under the hierarchical capillary effect, and the electrolyte slurry is used for preparing the electrolyte layer.
The positive plate also has the following optimization scheme:
the conductive slurry contains a conductive agent, and the conductive agent is at least one of graphite powder, carbon black, acetylene black, carbon tubes, ketjen black, polysaccharides, carbon fibers and sulfides.
The electrolyte slurry comprises the following raw materials in parts by weight:
i. at least one of lithium phosphorus oxynitride, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium ion-rich reverse perovskite, and
ii. Li7P3-xGexS11-x/2、Li2S-SiS2、LiI-Li2S-SiS2、Li2S-P2S5、LiF-Li2S-P2S5at least one of, and
iii, at least one of polyvinylidene fluoride, polyethylene oxide, polyether, polymethyl methacrylate, polyimide and polyacrylonitrile.
Li7P3-xGexS11-x/2The atomic number ratio of P to Ge in the alloy is 0-0.47.
The grain sizes of the powder i and the powder ii are 0.50-35 mu m, the grain size of the powder iii is 0.15-20 mu m, and the grain size of the powder iii is smaller than the grain sizes of the powder i and the powder ii.
The thickness of the solid electrolyte layer is 0.5-20 mu m.
The thickness of the conductive network layer is 0.5-3.5 mu m.
The positive active material in the positive material is formed by compounding any one of lithium iron phosphate, lithium cobaltate, lithium nickel manganese oxide, lithium nickel cobalt manganese aluminum oxide, vanadium sulfide, molybdenum oxide, molybdenum sulfide, iron sulfide and copper sulfide with activated carbon.
The positive electrode material layer is arranged on the current collector.
The invention also relates to a solid-state chemical power supply which adopts the positive plate.
The solid chemical power supply is manufactured by sequentially superposing the positive plate and the negative plate and then heating and pressurizing in vacuum.
Further, the solid-state chemical power supply also has the following optimization scheme:
the negative electrode sheet is provided with a negative electrode material, and the negative electrode material is at least one of active carbon, graphite, soft carbon, hard carbon, silicon or a silicon-containing compound.
The invention also relates to a manufacturing method of the positive plate, which comprises the following steps of preparing a conductive network layer between the positive material layer and the electrolyte layer:
coating conductive slurry on the surface of the anode material layer to form a conductive layer,
coating an electrolyte paste on the conductive layer to prepare an electrolyte layer,
the conductive layer is penetrated by an electrolyte slurry coated on the conductive layer under a graded capillary effect to form a conductive network layer.
The manufacturing method of the positive plate also has the following optimized structure:
and drying the conductive slurry coated on the anode material layer to form the conductive layer.
And the electrolyte slurry coated on the conductive layer is subjected to vacuum drying at 0 ℃ to form the electrolyte layer.
The positive plate of the invention takes the conductive network layer as a tie and a buffer layer for connecting the positive active material layer and the solid electrolyte layer, has flexible structure and high electronic and ionic conductivity, enables the composite polymer electrolyte slurry to uniformly permeate to the active material layer at low temperature through the hierarchical capillary effect, and then is solidified by high-temperature in-situ polymerization, thereby improving the mechanical strength of the composite electrolyte, the compatibility with an electrode interface and the stability, reducing the interface contact internal resistance between the active material and the solid electrolyte, and improving the poor physical contact between the electrode and the electrolyte caused by the volume deformation of the positive material in the charging and discharging process. In addition, the conductive network layer can be used as a protective layer to prevent side reactions and by-product transmission, thereby effectively improving the utilization rate of active substances. Meanwhile, the composite modified solid electrolyte has higher conductivity and lower reaction activity, can exert higher electrochemical performance of the positive active material, and improves the rate capability and the cycle durability of the all-solid battery.
Drawings
Fig. 1 is a schematic structural view of an all-solid battery prepared in example 1 of the present invention.
Fig. 2 is electrical performance data for different solid state chemical power source cells of examples and comparative examples.
In the figure, 1 is a composite polymer solid electrolyte layer, 2 is a conductive network layer, and 3 is a positive electrode material layer.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
The conductive network layer constructed by the single-phase or multi-phase conductive blend realizes the graded permeation of the electrolyte in a coating mode, increases the contact effect between the electrolyte and the anode material layer through intermolecular force, improves the electrode conductivity, improves the mechanical property and rheological property of the material, buffers the volume effect of the material in the charging and discharging process, and effectively improves the electron and ion transmission capability of the composite material so as to improve the multiplying power performance and cycle life of the material.
The following are typical but non-limiting examples of the invention:
example 1
The solid-state chemical power source comprises the following specific preparation steps:
step one, lithium iron phosphate: activated carbon: conductive agent: preparing a binder into uniform slurry according to a ratio of 79:16:2:3, coating the slurry on a current collector, and drying a pole piece in a drying oven at 100 ℃ for later use;
secondly, coating the conductive slurry on the dried positive pole piece prepared in the first step, and drying the positive pole piece again for later use;
step three, preparing composite polymer solid electrolyte slurry: uniformly mixing the LLZO powder and PEO, adding the mixture into an N, N-DMF organic solvent, magnetically stirring for 24-48h, and standing the obtained electrolyte slurry for later use;
and fourthly, coating the prepared electrolyte slurry on the pole piece to be used in the second step, and drying the pole piece overnight in vacuum at the temperature of 0 ℃.
And fifthly, sequentially overlapping the solid electrolyte membrane composite positive plate supported by the dried positive material and the graphite negative electrode, and applying vacuum heating and pressurizing, wherein the pressure is set to be 1.5MPa, the temperature is 80 ℃, and the time is 30 min.
The prepared solid chemical power supply is charged and discharged at constant current of 0.1C at 25 ℃, and the specific discharge capacity is 102 mAh.g-1The specific discharge capacity is maintained at 81mAh g after 100 cycles of circulation-1(80.39% of the initial specific discharge capacity) and the rate retention rate 2C/0.1C is 88.21%. The results show that the solid-state chemical power source using the LLZO and the PEO mixed as the electrolyte can realize long cycle performance and has high rate and capacity retention rate.
Example 2
The solid lithium ion battery comprises the following specific preparation steps:
step one, lithium iron phosphate: activated carbon: conductive agent: preparing a binder into uniform slurry according to the ratio of 79:16:2:3, coating the uniform slurry on a current collector, and drying a pole piece in a drying oven at 100 ℃ for later use;
secondly, coating the conductive slurry on the dried positive pole piece prepared in the first step, and drying the positive pole piece again for later use;
step three, preparing composite polymer solid electrolyte slurry: uniformly mixing the LLZO powder and PEO, adding the mixture into an N, N-DMF organic solvent, magnetically stirring for 24-48h, and standing the obtained electrolyte slurry for later use;
and fourthly, coating the prepared electrolyte slurry on the pole piece to be used in the second step, and drying the pole piece overnight in vacuum at the temperature of 0 ℃.
And fifthly, sequentially overlapping the solid electrolyte membrane composite positive plate supported by the dried positive material and the graphite negative electrode, and applying vacuum heating and pressurizing, wherein the pressure is set to be 1.0MPa, the temperature is 80 ℃, and the time is 30 min.
The prepared solid chemical power source is charged and discharged at constant current of 0.05 ℃ at 25 ℃, and the test result is shown in figure 2: from the constant current charge-discharge curve in fig. 2, it can be seen that the specific discharge capacity of the first loop of the battery is 110mAh g-1The specific discharge capacity after 100 cycles is kept at 89mAh g-1(81.02% of initial discharge specific capacity) and the rate retention rate 2C/0.1C is 89.33%. The results show that the solid chemical power source using the LLZO and the PEO mixed as the electrolyte can realize long cycle performance and has high rate and capacity retention rate when the cell is subjected to proper hot pressing treatment.
Example 3
The solid lithium ion battery comprises the following specific preparation steps:
step one, lithium iron phosphate: activated carbon: conductive agent: preparing a binder into uniform slurry according to the ratio of 79:16:2:3, coating the uniform slurry on a current collector, and drying a pole piece in a drying oven at 100 ℃ for later use;
secondly, coating the conductive slurry on the dried positive pole piece prepared in the first step, and drying the positive pole piece again for later use;
step three, preparing composite polymer solid electrolyte slurry: mixing Li2S-SiS2Uniformly mixing the electrolyte slurry with PEO, adding the mixture into an N, N-DMF organic solvent, magnetically stirring for 24-48h, and standing the obtained electrolyte slurry for later use;
and fourthly, coating the prepared electrolyte slurry on the pole piece to be used in the second step, and drying the pole piece overnight in vacuum at the temperature of 0 ℃.
And fifthly, sequentially superposing the dried solid electrolyte membrane composite positive plate supported by the positive electrode material and the graphite negative electrode, and applying vacuum heating and pressurizing, wherein the pressure is set to be 1.0MPa and the temperature is 80 ℃.
The prepared all-solid-state lithium battery is charged and discharged at constant current of 0.05 ℃ at 25 ℃, and the test result is shown in figure 2: from the constant current charge-discharge curve in fig. 2, it can be seen that the first-cycle specific discharge capacity of the battery is 115mAh · g-1The specific discharge capacity is kept at 95mAh g after 100 cycles of circulation-1(82.64% of initial specific discharge capacity) and the rate retention rate 2C/0.1C is 90.02%. The above results show that Li is used as a material for the lithium secondary battery2S-SiS2The all-solid-state lithium battery with PEO mixed as the electrolyte can realize long cycle performance and has high capacity and rate retention rate.
Example 4
The solid lithium ion battery comprises the following specific preparation steps:
step one, lithium iron phosphate: activated carbon: conductive agent: preparing a binder into uniform slurry according to a ratio of 79:16:2:3, coating the slurry on a current collector, and drying a pole piece in a drying oven at 100 ℃ for later use;
secondly, coating the conductive slurry on the positive pole piece which is prepared and dried in the first step, and drying the positive pole piece again for later use;
step three, preparing composite polymer solid electrolyte slurry: mixing LLZO powder and Li2S-SiS2Uniformly mixing the PEO and the PEO, adding the mixture into an N, N-DMF organic solvent, magnetically stirring for 24-48h, and standing the obtained electrolyte slurry for later use;
and fourthly, coating the prepared electrolyte slurry on the electrode plate to be used in the second step, and drying the electrode plate overnight in vacuum at the temperature of 0 ℃.
And fifthly, sequentially superposing the dried solid electrolyte membrane composite positive plate supported by the positive electrode material and the graphite negative electrode, and applying vacuum heating and pressurizing, wherein the pressure is set to be 1.0MPa and the temperature is 80 ℃.
The prepared all-solid-state lithium battery is charged and discharged at constant current of 0.05 ℃ at 25 ℃, and the test result is shown in figure 2: from the constant current charge-discharge curve in fig. 2, it can be seen that the specific discharge capacity of the first loop of the battery is 120mAh g-1The specific discharge capacity is maintained at 102mAh g after 100 cycles of circulation-1(85.01% of the initial specific discharge capacity) and the rate retention rate 2C/0.1C was 92.12%. The above results show that LLZO and Li are used as raw materials2S-SiS2The all-solid-state lithium battery with PEO mixed as the electrolyte has the advantages of oxides and sulfides, can realize long cycle performance, and has high capacity and rate retention rate.
Comparative example 1
The solid chemical power source is prepared by the following specific steps:
step one, lithium nickel cobalt manganese oxide: activated carbon: conductive agent: preparing a binder into uniform slurry according to the ratio of 79:16:2:3, coating the uniform slurry on a current collector, and drying a pole piece in a drying oven at 100 ℃ for later use;
secondly, coating the conductive slurry on the dried positive pole piece prepared in the first step, and drying the positive pole piece again for later use;
step three, preparing composite polymer solid electrolyte slurry: uniformly mixing the LLZO powder and PEO, adding the mixture into an N, N-DMF organic solvent, magnetically stirring for 24-48h, and standing the obtained electrolyte slurry for later use;
and fourthly, coating the prepared electrolyte slurry on the pole piece to be used in the second step, and drying the pole piece overnight in vacuum at the temperature of 0 ℃.
And fifthly, sequentially overlapping the solid electrolyte membrane composite positive plate supported by the dried positive material and the graphite negative electrode, and applying vacuum heating and pressurizing, wherein the pressure is set to be 1.0MPa, the temperature is 80 ℃, and the time is 30 min.
The prepared solid chemical power source is charged and discharged at constant current of 0.05 ℃ at 25 ℃, and the test result is shown in figure 2: from the constant current charge-discharge curve in fig. 2, it can be seen that the specific discharge capacity of the first cycle of the battery is 125mAh g-1After 100 cycles, the specific discharge capacity is maintained at 102mAh g < -1 > (which is 81.67 percent of the initial specific discharge capacity), and the rate retention rate 2C/0.1C is 87.43 percent. The results show that the electrolyte prepared by mixing the LLZO and the PEO is also suitable for other anode material systems, the solid-state chemical power supply can realize long cycle performance, and the rate and the capacity retention rate are high.
Comparative example 2
The solid chemical power source is prepared by the following specific steps:
step one, lithium nickel cobalt manganese oxide: activated carbon: conductive agent: preparing a binder into uniform slurry according to the ratio of 79:16:2:3, coating the uniform slurry on a current collector, and drying a pole piece in a drying oven at 100 ℃ for later use;
secondly, coating the conductive slurry on the positive pole piece which is prepared and dried in the first step, and drying the positive pole piece again for later use;
third stepStep one, preparing composite polymer solid electrolyte slurry: mixing LLZO powder and Li2S-SiS2Uniformly mixing the electrolyte slurry with PEO, adding the mixture into an N, N-DMF organic solvent, magnetically stirring for 24-48h, and standing the obtained electrolyte slurry for later use;
and fourthly, coating the prepared electrolyte slurry on the pole piece to be used in the second step, and drying the pole piece overnight in vacuum at the temperature of 0 ℃.
And fifthly, sequentially overlapping the solid electrolyte membrane composite positive plate supported by the dried positive material and the graphite negative electrode, and applying vacuum heating and pressurizing, wherein the pressure is set to be 1.0MPa, the temperature is 80 ℃, and the time is 30 min.
The prepared solid chemical power source is charged and discharged at constant current of 0.05 ℃ at 25 ℃, and the test result is shown in figure 2: from the constant current charge-discharge curve in fig. 2, it can be seen that the specific discharge capacity of the first loop of the battery is 131mAh g-1After 100 cycles, the specific discharge capacity is kept at 111mAh g-1 (which is 84.95% of the initial specific discharge capacity), and the rate retention rate 2C/0.1C is 90.92%. The above results show that LLZO and Li are used as raw materials2S-SiS2The solid-state chemical power source can also realize long cycle performance and has high rate and capacity retention rate.
Comparative example 3
The solid chemical power source is prepared by the following specific steps:
step one, lithium iron phosphate: conductive agent: preparing a binder into uniform slurry according to the ratio of 95:2:3, coating the uniform slurry on a current collector, and drying a pole piece in a drying oven at 100 ℃ for later use;
secondly, coating the conductive slurry on the dried positive pole piece prepared in the first step, and drying the positive pole piece again for later use;
step three, preparing composite polymer solid electrolyte slurry: uniformly mixing LLZO powder and PEO, adding the mixture into an N, N-DMF organic solvent, magnetically stirring for 24-48h, and standing the obtained electrolyte slurry for later use;
and fourthly, coating the prepared electrolyte slurry on the pole piece to be used in the second step, and drying the pole piece overnight in vacuum at the temperature of 0 ℃.
And fifthly, sequentially overlapping the solid electrolyte membrane composite positive plate supported by the dried positive material and the graphite negative electrode, and applying vacuum heating and pressurizing, wherein the pressure is set to be 1.0MPa, the temperature is 80 ℃, and the time is 30 min.
The prepared solid chemical power source was charged and discharged at a constant current of 0.05C at 25C, and the test results are shown in fig. 2: from the constant current charge-discharge curve in fig. 2, it can be seen that the specific discharge capacity of the first loop of the battery is 108mAh g-1The specific discharge capacity is kept at 87mAh g after 100 cycles of circulation-1(80.75% of initial specific discharge capacity) and the rate retention ratio 2C/0.1C was 86.55%. The solid chemical power source with the electrolyte prepared by mixing the LLZO and the PEO can realize long cycle performance and has high rate and capacity retention rate.
It can be seen from the above examples and comparative examples that the all-solid-state lithium battery with composite electrolyte has the advantages of both oxide and sulfide, and due to the electrolyte graded permeation effect and the protection of the conductive layer, the high reactivity between the active material and the solid electrolyte can be inhibited, the formation of a space charge layer can be avoided, the interface contact resistance can be reduced, and the rate capability and the cycle durability of the solid chemical power source can be improved. Meanwhile, the method is simple in process, can be used for large-scale production, and is beneficial to industrial application of the solid chemical power supply.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of the raw materials of the product of the present invention, and the addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (10)

1. A positive plate comprises a positive material layer and an electrolyte layer, and is characterized in that: a conductive network layer is arranged between the anode material layer and the electrolyte layer, and the conductive network layer is as follows: the conductive layer is formed by the penetration of the electrolyte slurry coated on the conductive layer under the hierarchical capillary effect, and the electrolyte slurry is used for preparing the electrolyte layer.
2. The positive electrode sheet according to claim 1, wherein the raw materials of the electrolyte slurry comprise the following powders:
i. at least one of lithium phosphorus oxynitride, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium ion-rich reverse perovskite, and
ii. Li7P3-xGexS11-x/2、Li2S-SiS2、LiI-Li2S-SiS2、Li2S-P2S5、LiF-Li2S-P2S5at least one of, and
iii, at least one of polyvinylidene fluoride, polyethylene oxide, polyether, polymethyl methacrylate, polyimide and polyacrylonitrile.
3. The positive electrode sheet according to claim 2, wherein Li is7P3-xGexS11-x/2The atomic number ratio of P to Ge in the alloy is 0-0.47.
4. The positive electrode sheet according to claim 2, wherein the particle sizes of the powder i and the powder ii are both 0.50 to 35 μm, the particle size of the powder iii is 0.15 to 20 μm, and the particle size of the powder iii is smaller than the particle sizes of the powder i and the powder ii.
5. The positive electrode sheet according to claim 1, wherein the electrolyte layer has a thickness of 0.5 to 20 μm.
6. The positive plate according to claim 1, characterized in that the thickness of the conductive network layer is 0.5-3.5 μm.
7. The positive electrode sheet according to claim 1, wherein the positive electrode active material in the positive electrode material layer is a composite composition of activated carbon and any one of lithium iron phosphate, lithium cobaltate, lithium nickel manganese oxide, lithium nickel manganese cobalt oxide, lithium vanadium oxide, vanadium sulfide, molybdenum oxide, molybdenum sulfide, iron sulfide, and copper sulfide.
8. A solid state chemical power supply characterized by using the positive electrode sheet according to any one of claims 1 to 7.
9. A solid state chemical power supply as claimed in claim 8, produced by vacuum heating and pressing of the stack of positive and negative plates.
10. A manufacturing method of a positive plate is characterized by comprising the following steps of preparing a conductive network layer between a positive material layer and an electrolyte layer:
coating conductive slurry on the surface of the positive electrode material layer to prepare a formed conductive layer,
coating an electrolyte slurry on the conductive layer to prepare an electrolyte layer,
the conductive layer is penetrated by an electrolyte paste coated on the conductive layer under a graded capillary effect to form a conductive network layer.
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