CN108258323B - A kind of production method of high specific energy solid lithium battery - Google Patents

Abstract

The invention discloses a kind of production methods of high specific energy solid lithium battery, pore creating material pore-creating in positive/negative plate coating procedure is used first, electrode slice obtained after roll-in in pole piece single side surface coating film polyelectrolyte solution, the unilateral positive plate with electrolyte layer and negative electrode tab are finally assembled into all-solid lithium-ion battery by way of winding or lamination method.Compared with prior art, the hole that polyelectrolyte solution can be obtained by pore creating material in the method for the invention infiltrates through inside pole piece, obtained pole piece and polymer dielectric interfacial contact area are larger, increase the ionic conductivity of electrode material, the solid lithium battery being obtained by this method has many advantages, such as that interface resistance is low, and energy density is high, stability and highly-safe.

Description

A kind of manufacturing method of high specific energy all-solid-state lithium battery

technical field

The invention belongs to the field of lithium-ion batteries, and in particular relates to a method for manufacturing a high-specific-energy all-solid-state lithium battery.

Background technique

Lithium-ion power batteries have the advantages of high energy density, long life, and environmental protection, and are currently the most widely used power source for new energy vehicles. With the continuous promotion of lithium-ion battery new energy vehicles, traditional lithium-ion power batteries have been difficult to meet the safety and mileage requirements of vehicles. In particular, the electrolytes used in current lithium-ion power batteries are mostly flammable and explosive organic solvent systems, which pose a serious safety hazard when used in the automotive field. All-solid-state lithium-ion power batteries made of solid electrolytes can greatly improve the performance of power batteries. Security has received widespread attention.

The closeness of the contact between the solid electrolyte and the electrode in the all-solid lithium battery directly affects the transmission of lithium ions. The solid lithium battery prepared by simple lamination and hot pressing of the electrode sheet and the solid electrolyte film has too large interface impedance; Solid electrolyte can improve the electrolyte/electrode interface contact and reduce interface impedance, but the amount of electrolyte added to the electrode is usually relatively large (20% to 30% mass ratio), which will reduce the active material content of the pole piece, resulting in a large loss of specific capacity of the pole piece .

Contents of the invention

In order to overcome the above-mentioned defects in the prior art, the object of the present invention is to provide a method for manufacturing a high-specific-energy all-solid-state lithium battery. The present invention can improve the interface between the electrolyte and the electrode sheet without adding electrolyte during the electrode sheet coating process. Contact, on the premise of maintaining a high specific capacity of the pole piece, reduces the electrode/electrolyte interface resistance.

To achieve the above object, the present invention adopts the following technical solutions:

A method for manufacturing a high-specific-energy all-solid-state lithium battery, comprising the following steps:

Step 1: Dissolving the positive electrode active material, conductive agent, binder, and pore-forming agent in a solvent in proportion to prepare a positive electrode slurry, coating the positive electrode slurry on the positive electrode current collector, and obtaining Positive plate;

Step 2: Dissolving the negative electrode material, conductive agent, binder, and pore-forming agent in the solvent in proportion to prepare negative electrode slurry, coating the negative electrode slurry on the negative electrode current collector, and obtaining the negative electrode through heat treatment and rolling treatment piece;

Step 3: Dissolve the polymer electrolyte, filler, and lithium salt in the solvent in proportion to prepare several electrolyte solutions with different solid contents; apply the electrolyte solutions on the positive and negative electrodes sequentially in order of solid content from low to high One side surface, after each coating, heat treatment is carried out, and finally a positive electrode sheet and a negative electrode sheet with an electrolyte layer on one side are obtained;

Step 4: By winding or stacking, assemble the positive electrode sheet and negative electrode sheet with an electrolyte layer on one side produced in step 3 into an all-solid lithium-ion battery cell, and obtain an all-solid-state lithium-ion battery after hot pressing and packaging.

Further, the conductive agent described in step 1 and step 2 is one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, carbon fiber, carbon nanotube and graphene, and the binder is One or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose and styrene-butadiene rubber, and the pore-forming agent is ammonium bicarbonate, ammonium acetate, ammonium nitrate and carbonic acid One or more of ammonium.

Further, the positive electrode active material in step 1 is one or more of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickel manganese oxide and lithium-rich positive electrode materials, and the solvent is N- Methylpyrrolidone, the positive current collector is aluminum foil;

In step 2, the negative electrode active material is one or more of graphite, hard carbon and silicon-based materials, the solvent is deionized water, and the negative electrode current collector is copper foil.

Further, the percentage of each solid component in the positive electrode slurry to the total solid mass is: positive electrode active material 89%-97.9%, conductive agent 1%-5%, binder 1%-3%, pore-forming agent 0.1% to 3%, and the positive electrode slurry has a solid content of 30% to 80%.

Further, the percentage of each solid component in the negative electrode slurry to the total solid mass is: negative electrode active material 91%-98.4%, conductive agent 0.5%-3%, binder 1%-3%, pore-forming agent 0.1% to 3%, and the solid content of the negative electrode slurry is 30% to 60%.

Further, the polymer electrolyte described in step three is one or more of polyethylene oxide, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, and polyvinyl chloride; The filler is nano Al ₂ O ₃ , nano SiO ₂ inorganic filler or metal organic framework material organic filler; the lithium salt is one or more of LiCF ₃ SO ₃ , LiClO ₄ , LiPF ₆ and LiI; the solvent is N-Methylpyrrolidone.

Further, the percentage of each solid component of the electrolyte solution to the total solid mass is: 80% to 98.5% of the polymer electrolyte, 0.5% to 10% of the filler; 1% to 10% of the lithium salt; The solid content of the electrolyte solution is 1%-80%.

Further, the thickness of the polymer electrolyte layer coated on the surface of the positive electrode sheet and the negative electrode sheet in step three is 5-50 μm, preferably 10-20 μm.

Further, the heat treatment temperature in step 1 is 80-140°C, and the treatment time is 60-600s; the heat treatment temperature in step 2 is 60-120°C, and the treatment time is 60-600s; the heat treatment temperature in step 3 is 60-120°C, and the treatment time is 60～600s.

Further, in step 4, the hot-pressing temperature during the assembling process of the solid-state lithium battery is 80-160° C., the pressure is 5-10 MPa, and the time is 1-200 s.

Compared with the prior art, the present invention has the following beneficial technical effects:

Compared with the traditional method of adding too much solid electrolyte to the electrode material, which leads to a large loss of the specific capacity of the pole piece, the present invention does not dope the polymer solid electrolyte during the coating process of the positive and negative pole pieces, and maintains the specific capacity of the electrode. unchanged; the polymer electrolyte solution is coated or sprayed on the surface of the positive electrode and the negative electrode, the polymer electrolyte solution can penetrate into the inside of the electrode through the pores obtained by the pore-forming agent, and the contact area between the obtained electrode and the polymer electrolyte interface is relatively small. Large, and finally assembled into a battery cell, a tight positive electrode-electrolyte-negative electrode three-layer combination is formed after hot-pressing treatment, which can effectively reduce the interface resistance of solid-state lithium batteries; compared with liquid electrolyte lithium batteries, it has higher safety.

Detailed ways

Embodiments of the present invention are described in further detail below:

A method for manufacturing a high-specific-energy all-solid-state lithium battery, comprising the following steps:

Step (1): Dissolve the positive electrode active material, conductive agent, binder, and pore-forming agent in a solvent in a certain proportion to prepare a positive electrode slurry, apply the positive electrode slurry on the positive electrode current collector, and heat-treat and roll Press treatment to obtain the positive electrode sheet;

Step (2): Dissolve the negative electrode material, conductive agent, binder, and pore-forming agent in a solvent in a certain proportion to prepare negative electrode slurry, apply the negative electrode slurry on the negative electrode current collector, and heat-treat and roll Process to obtain the negative electrode sheet;

Step (3): Dissolve polymer electrolytes, fillers, lithium salts, etc. in a solvent in a certain proportion to prepare several electrolyte solutions with different solid contents; apply the electrolyte solutions on the electrodes in order of solid contents from low to high. One side surface of the sheet, heat treatment is required for each coating, and finally a positive electrode sheet and a negative electrode sheet with an electrolyte layer on one side are obtained;

Step (4): Assemble the positive electrode sheet and negative electrode sheet with an electrolyte layer on one side produced in step (3) into an all-solid-state lithium-ion battery by winding or stacking;

In steps (1), (2), the conductive agent is one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, graphene, etc.; the binding agent is One or more of polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), etc.; The pore-forming agent is one or more of ammonium bicarbonate, ammonium acetate, ammonium nitrate, and ammonium carbonate;

In step (1), the positive electrode active material includes one or more of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickel manganese oxide, and lithium-rich positive electrode materials; the solvent is N- Methylpyrrolidone (NMP); the percentage of each solid component of the positive electrode slurry to the total solid mass is: 89% to 97.9% of the positive electrode active material, 1% to 5% of the conductive agent, and 1% to 3% of the binder , 0.1%-3% pore-forming agent, wherein the optimal mass ratio of pore-forming agent in the solid component of the positive electrode slurry is 0.5%-1.5%; the solid content of the slurry can be adjusted between 30%-80%; the positive electrode The current collector is aluminum foil, the heat treatment temperature is 80-140°C, and the treatment time is 60-600s;

In step (2), the negative electrode active material includes one or more of graphite, hard carbon, and silicon-based materials; the solvent is deionized water; each solid component of the negative electrode slurry accounts for 1% of the total solid mass The percentages are: 91% to 98.4% of the negative active material, 0.5% to 3% of the conductive agent, 1% to 3% of the binder, and 0.1% to 3% of the pore forming agent, wherein the pore forming agent is in the solid component of the negative electrode slurry The optimal mass ratio is 0.5%-1.5%; the solid content of the slurry can be adjusted between 30% and 60%; the negative electrode current collector is copper foil, the heat treatment temperature is 60-120°C, and the treatment time is 60-600s;

In step (3), the polymer electrolyte is polyethylene oxide (PEO) based, polymethyl methacrylate (PMMA) based, polyacrylonitrile (PAN) based, polyvinylidene fluoride (PVDF) based, polychlorinated One or more of ethylene (PVC) series, etc., preferably PEO series; the filler is one or more of nano-Al ₂ O ₃ , nano-SiO ₂ inorganic fillers or metal-organic framework materials (MOFs); the The lithium salt includes one or more of LiCF ₃ SO ₃ , LiClO ₄ , LiPF ₆ , LiI, etc.; the solvent is N-methylpyrrolidone (NMP); the solid components of the electrolyte solution account for the total solid The percentage by mass is: polymer electrolyte 80%-98.5%, the proportion of filler is 0.5%-10%; the proportion of lithium salt is 1%-10%; the solid content of the electrolyte solution can be adjusted between 1%-80% respectively; There are 1 to 6 kinds of electrolytic solutions with different solid contents in the configuration; when the solid content of the electrolytic solution is one, it can also be applied multiple times in multiple times; the coating method of the electrolytic solution includes slurry coating method, spraying method, etc.; the heat treatment temperature is 60-120°C, and the treatment time is 60-600s; the thickness of the polymer electrolyte layer coated on the surface of the positive and negative electrodes is 5-50 μm; The thickness of the polymer electrolyte layer on the surface of the positive and negative pole pieces is preferably 10-20 μm;

In step (4), the hot pressing temperature required in the assembling process of the solid-state lithium battery is 80-160° C., the pressure is 5-10 MPa, and the time is 1-200 s.

Below in conjunction with embodiment the present invention is described in further detail:

Example 1

(1) Positive electrode pulping is according to the following mass ratio: nickel cobalt lithium manganese oxide (NCM523) positive electrode material 97.9%, Super P Li conductive agent 1%, PVDF (HSV-900) binder 1%; ammonium bicarbonate pore-forming agent 0.1%, through a double planetary mixer, using NMP as a solvent to prepare positive electrode slurry with a solid content of 65%. Coating the positive electrode slurry on the aluminum foil current collector, heat treatment at 140°C for 60s, and then roll pressing to obtain the positive electrode sheet;

(2) Negative electrode pulping is according to the following mass ratio: 98.4% of artificial graphite G9, 0.5% of Super P Li conductive agent, 1% of CMC (Daicel) binder, 0.1% of ammonium bicarbonate pore-forming agent, through a double planetary mixer , using deionized water as a solvent to prepare negative electrode slurry with a solid content of 45%. Coating the negative electrode slurry on the copper foil current collector, heat treatment at 120°C for 60s, and then roll pressing to obtain the negative electrode sheet;

(3) The electrolyte solution is prepared according to the following mass ratio: PEO polymer electrolyte 98.5%, Al ₂ O ₃ filler ratio 0.5%; LiPF ₆ lithium salt ratio 1%; through a double planetary mixer, NMP is used as a solvent to prepare solid content respectively 1% and 10% electrolyte solutions. Then, the above-mentioned electrolyte solution was evenly sprayed on the surface of the positive electrode and the negative electrode sheet in sequence according to the solid content, and a uniform 10 μm thick electrolyte layer was formed on the electrode sheet after heat treatment at 120°C for 60s.

(4) Die-cut the positive electrode sheet and negative electrode sheet with electrolyte on one side, and assemble them into a 2Ah soft-packed battery cell by lamination. After welding the tabs, they are hot-pressed at 160°C and 5Mpa for 1s, and packaged with aluminum-plastic film to form a complete battery. Solid state lithium battery.

Example 2

(1) Positive electrode pulping is in accordance with the following mass ratio: nickel cobalt lithium aluminate (NCA) positive electrode material 89%, acetylene black conductive agent 5%, PVA binder 3%; ammonium carbonate pore-forming agent 3%, through a double planetary mixer , using NMP as a solvent to prepare positive electrode slurry with a solid content of 80%. Coating the positive electrode slurry on the aluminum foil current collector, heat treatment at 80°C for 600s, and then roll pressing to obtain the positive electrode sheet;

(2) Negative electrode pulping is according to the following mass ratio: silicon carbon accounts for 91%, carbon nanotube conductive agent 3%, SBR binding agent 3%, ammonium carbonate pore-forming agent 3%, pass through double planetary mixer, take deionized water as The solvent was prepared into negative electrode slurry with a solid content of 60%. Coating the negative electrode slurry on the copper foil current collector, heat treatment at 60°C for 600s, and then roll pressing to obtain the negative electrode sheet;

(3) The electrolyte solution is in accordance with the following mass ratio: PVC polymer electrolyte 80%, SiO ₂ filler ratio is 10%; LiCF ₃ SO ₃ lithium salt ratio is 10%; through a double planetary mixer, NMP is used as a solvent to prepare a solid content of 10% %, 40%, 80% electrolyte solution. Then, the above-mentioned electrolyte solution was evenly sprayed on the surface of the positive electrode and the negative electrode sheet in sequence according to the solid content, and a uniform 5 μm thick electrolyte layer was formed on the electrode sheet after heat treatment at 60°C for 600s.

(4) Die-cut the positive electrode sheet and negative electrode sheet with electrolyte on one side, and assemble them into a 2Ah soft-packed battery cell by lamination. After welding the tabs, they are hot-pressed at 80°C and 10Mpa for 200s, and packaged with aluminum-plastic film to form a complete battery. Solid state lithium battery.

Example 3

(1) Positive electrode pulping is according to the following mass ratio: 95% of lithium nickel manganese oxide positive electrode material, 2% of graphene conductive agent, 1.5% of PTFE binder; The solvent was prepared into positive electrode slurry with a solid content of 30%. Coating the positive electrode slurry on the aluminum foil current collector, heat treatment at 140°C for 60s, and then roll pressing to obtain the positive electrode sheet;

(2) Negative electrode pulping is according to the following mass ratio: hard carbon accounts for 93%, Super P Li conductive agent 2%, CMC (Daicel) binder 3.5%, ammonium acetate pore-forming agent 1.5%, pass through double planetary mixer, with Deionized water was used as a solvent to prepare negative electrode slurry with a solid content of 30%. Coating the negative electrode slurry on the copper foil current collector, heat treatment at 100°C for 350s, and then roll pressing to obtain the negative electrode sheet;

(3) The electrolyte solution is in accordance with the following mass ratio: PAN polymer electrolyte 85%, MOFs filler ratio is 10%; LiClO ₄ lithium salt ratio is 5%; through double planetary mixer, NMP is used as solvent to prepare solid content 1%, 5 %, 7%, 12%, 15%, 20% electrolyte solution. Then, the above-mentioned electrolyte solution was evenly sprayed on the surface of the positive electrode and the negative electrode sheet in sequence according to the solid content, and a uniform 50 μm thick electrolyte layer was formed on the electrode sheet after heat treatment at 100°C for 120s.

(4) Die-cut the positive electrode sheet and negative electrode sheet with electrolyte on one side, and assemble them into a 2Ah soft-packed battery cell by lamination. After welding the tabs, they are heat-pressed at 120°C and 6Mpa for 60s, and packaged with aluminum-plastic film to form a complete battery. Solid state lithium battery.

Example 4

(1) Positive electrode pulping is according to the following mass ratio: 93.5% of lithium iron phosphate positive electrode material, 3% of carbon fiber conductive agent, 3% of PVDF (HSV-900) binder; 0.5% of ammonium nitrate pore-forming agent, passed through a double planetary mixer, A cathode slurry with a solid content of 65% was prepared using NMP as a solvent. Coating the positive electrode slurry on the aluminum foil current collector, heat treatment at 100°C for 300s, and then roll pressing to obtain the positive electrode sheet;

(2) Negative electrode pulping is in accordance with the following mass ratio: 96% of artificial graphite G9, 1% of Ketjen black conductive agent, 1% of CMC (Daicel) binder, 1.5% of SBR binder, and 0.5% of ammonium nitrate pore-forming agent %, through a double planetary mixer, using deionized water as a solvent to prepare a negative electrode slurry with a solid content of 45%. Coating the negative electrode slurry on the copper foil current collector, heat treatment at 60°C for 600s, and then roll pressing to obtain the negative electrode sheet;

(3) Electrolyte solution according to the following mass ratio: PVDF polymer electrolyte 90%, _Al2O3 filler ratio is ₅ %; LiI lithium salt ratio is 5%; through double planetary mixer, NMP is used as the solvent to prepare 80% solid content electrolyte solution. Then the electrolyte solution was evenly sprayed on the surface of one side of the positive electrode and the negative electrode sheet by spraying method, and a uniform 20 μm thick electrolyte layer was formed on the electrode sheet after heat treatment at 80°C for 300s.

(4) Die-cut the positive electrode sheet and negative electrode sheet with electrolyte on one side, and assemble them into 2Ah soft-packed batteries by lamination. After welding the tabs, they are hot-pressed at 100°C and 8Mpa for 100s, and packaged with aluminum-plastic film to form a complete battery. Solid state lithium battery.

Example 5

(1) Positive electrode pulping according to the following mass ratio: lithium-rich positive electrode material 63%, lithium iron phosphate positive electrode material 30.5%, carbon fiber conductive agent 2%, acetylene black conductive agent 1%, PVDF (HSV-900) binder 2% 1% of PVA binder, 0.2% of ammonium nitrate pore-forming agent, 0.3% of ammonium bicarbonate pore-forming agent, prepared into a positive electrode slurry with a solid content of 65% by using NMP as a solvent through a double planetary mixer. Coating the positive electrode slurry on the aluminum foil current collector, heat treatment at 120°C for 100s, and then roll pressing to obtain the positive electrode sheet;

(2) Negative electrode pulping according to the following mass ratio: artificial graphite G9 accounts for 66%, silicon carbon negative electrode material 30%, conductive carbon black 1%, CMC (Daicel) binder 1%, SBR binder 1%, nitric acid 1% ammonium pore-forming agent was prepared into a negative electrode slurry with a solid content of 45% by using a double planetary mixer and using deionized water as a solvent. Coating the negative electrode slurry on the copper foil current collector, heat treatment at 130°C for 90s, and then roll pressing to obtain the negative electrode sheet;

(3) The electrolyte solution is in accordance with the following mass ratio: PMMA electrolyte 60%, PVA electrolyte 30%, Al ₂ O ₃ filler ratio is 2%, SiO ₂ filler ratio 3%; LiI lithium salt ratio is 2%, LiClO ₄ lithium salt ratio 3%; through a double planetary mixer, NMP is used as a solvent to prepare an electrolyte solution with a solid content of 6% and 80%. Then, the electrolyte solution was evenly sprayed on the surface of one side of the positive electrode and the negative electrode sheet by spraying method, and a uniform 25 μm thick electrolyte layer was formed on the electrode sheet after heat treatment at 90° C. for 150 s.

(4) Die-cut the positive electrode sheet and negative electrode sheet with electrolyte on one side, and assemble them into a 2Ah soft-packed battery cell by lamination. After welding the tabs, they are hot-pressed at 105°C and 8Mpa for 105s, and packaged with aluminum-plastic film to form a complete battery. Solid state lithium battery.

Comparative example 1

(1) The positive electrode slurry is prepared according to the following mass ratio: nickel cobalt lithium manganese oxide (NCM523) positive electrode material 96%, Super PLi conductive agent 2%, HSV-900PVDF binder 2%; through a double planetary mixer, NMP is used as a solvent preparation Form a positive electrode slurry with a solid content of 65%, apply the positive electrode slurry to an aluminum foil current collector, heat-treat at 100°C for 60 seconds, and then roll to obtain a positive electrode sheet;

(2) Negative electrode pulping is according to the following mass ratio: artificial graphite G9 accounts for 96%, Super P Li conductive agent 1%, CMC binder 1.5%, SBR binder 1.5%, pass through double planetary mixer, take deionized water as The solvent is prepared into a negative electrode slurry with a solid content of 45%, and the negative electrode slurry is coated on a copper foil current collector, after heat treatment at 90°C for 60s, and then rolled to obtain a negative electrode sheet;

(3) The electrolyte solution is in accordance with the following mass ratio: PEO polymer electrolyte 95%, Al ₂ O ₃ filler ratio is 2%; LiPF ₆ lithium salt ratio is 3%; NMP is used as a solvent to prepare an electrolyte solution with a solid content of 15%, Then a separate electrolyte membrane was prepared by solvent evaporation method.

(4) Die-cut the prepared positive electrode sheet, negative electrode sheet, and electrolyte sheet, and assemble them into a 2Ah soft-packed battery cell by lamination. After welding the tabs, they are hot-pressed at 130°C and 5Mpa for 30s, and packaged with aluminum-plastic film to form a complete battery. Solid state lithium battery.

Comparative example 2

(1) Positive electrode pulping is based on the following mass ratio: 80% of lithium iron phosphate positive electrode material, 2% of Super PLi conductive agent, 16% of PEO solid electrolyte, 1% of Al ₂ O ₃ filler, and 1% of LiPF ₆ lithium salt ; Prepare a positive electrode slurry with a solid content of 65% by using NMP as a solvent with a double planetary mixer, apply the positive electrode slurry to an aluminum foil current collector, heat-treat at 100°C for 60 seconds, and then roll to obtain a positive electrode sheet;

(2) Negative electrode pulping is based on the following mass ratio: 81% artificial graphite G9, 1% Super P Li conductive agent, 16% PEO solid electrolyte, 1% Al ₂ O ₃ filler, and 1% LiPF ₆ lithium salt ;, through a double planetary mixer, NMP was used as a solvent to prepare a negative electrode slurry with a solid content of 45%, and the negative electrode slurry was coated on a copper foil current collector, and after heat treatment at 90°C for 60s, the negative electrode was obtained by rolling. piece;

(3) The electrolyte solution is in accordance with the following mass ratio: PEO polymer electrolyte 95%, Al ₂ O ₃ filler ratio is 2%; LiPF ₆ lithium salt ratio is 3%; NMP is used as a solvent to prepare an electrolyte solution with a solid content of 15%, Then a separate electrolyte membrane was prepared by solvent evaporation method.

(5) Die-cut the prepared positive electrode sheet, negative electrode sheet, and electrolyte sheet, and assemble them into a 2Ah soft-packed battery cell by lamination. After welding the tabs, they are hot-pressed at 120°C and 8Mpa for 20s, and packaged with aluminum-plastic film to form a complete battery. Solid state lithium battery.

The solid-state lithium-ion batteries produced in Examples 1-4 and Comparative Examples 1-2 were tested for discharge capacity, battery first effect, and DC internal resistance according to the following methods.

testing method:

Discharge capacity: the battery is charged at 0.2C constant current and constant voltage to 4.2V, charged at constant voltage until the current is ≤0.05C, and discharged at 0.2C constant current to 2.75V;

Battery capacity retention rate: the battery is charged to 4.2V with 1C constant current and constant voltage, charged at constant voltage until the current is ≤0.05C, discharged at 1C constant current to 2.75V, the ratio of the first discharge capacity to the discharge capacity after 500 cycles;

DC internal resistance: at room temperature, discharge the battery at 1C constant current to 2.75V, and leave it for 60 minutes; charge the battery at 1C constant current and constant voltage to 4.2V, charge it at constant voltage until the current ≤ 0.05C, and leave it for 60 minutes; discharge at 1C constant current for 30 minutes ;Stand aside for 60min; 1C constant current discharge for 10s, lower limit voltage 2.5V. Record the open circuit voltage and current during the pulse discharge process, and calculate the DC internal resistance R. The formula for calculating DC internal resistance is as follows:

Among them, V _initial and V _final are the initial and final voltages of the pulse discharge process, respectively, and I _initial and I _final are the initial and final currents of the pulse discharge process, respectively.

Table 1 is the test results of above-mentioned embodiment and comparative example discharge capacity, cycle performance and DC internal resistance

From the test results of the examples and comparative examples in Table 1, it can be seen that the solid-state lithium battery prepared by the design scheme of the present invention has a low DC internal resistance, because the polymer electrolyte is directly coated on the positive electrode sheet and the negative electrode by coating. On the surface of the sheet, a small amount of polymer electrolyte penetrates into the interior of the electrode sheet through the pores formed by the pore-forming agent, which increases the contact area of the electrode sheet/electrolyte, not only improves the ionic conductivity of the electrode sheet, but also reduces the electrode sheet/electrolyte to a certain extent. The impedance between the interfaces and the cycle performance of the battery are also significantly improved; while for the conventional scheme in the comparative example, the contact surface is formed between the pole piece and the electrolyte by hot pressing, and the contact area between the two is small, so the internal resistance of the battery is large, and the battery’s The cycle stability is also poor; when there are more polymer electrolytes mixed in the positive and negative pole pieces, the energy density of the battery will also be greatly reduced. As shown in Table 1, the all-solid-state lithium Battery discharge capacity is low.

Claims (8)

1. A method for making a high specific energy all-solid-state lithium battery, comprising the following steps: Step 1: Dissolving the positive electrode active material, conductive agent, binder, and pore-forming agent in a solvent in proportion to prepare a positive electrode slurry. The percentage of each solid component in the positive electrode slurry to the total solid mass is: positive electrode 89% to 97.9% active material, 1% to 5% conductive agent, 1% to 3% binder, 0.1% to 3% pore forming agent, and the solid content of positive electrode slurry is 30% to 80%. The material is coated on the positive electrode current collector, and the positive electrode sheet is obtained through heat treatment and rolling treatment; Step 2: Dissolve the negative electrode material, conductive agent, binder, and pore-forming agent in the solvent in proportion to prepare negative electrode slurry. The percentage of each solid component in the negative electrode slurry to the total solid mass is: negative electrode activity 91% to 98.4% of the material, 0.5% to 3% of the conductive agent, 1% to 3% of the binder, 0.1% to 3% of the pore forming agent, and the solid content of the negative electrode slurry is 30% to 60%. Coated on the negative electrode current collector, after heat treatment and rolling treatment to obtain the negative electrode sheet; Step 3: Dissolve the polymer electrolyte, filler, and lithium salt in the solvent in proportion to prepare several electrolyte solutions with different solid contents. The percentage of each solid component of the electrolyte solution to the total solid mass is: polymer electrolyte 80% ~98.5%, the filler ratio is 0.5%~10%; the lithium salt ratio is 1%~10%; the solid content of the electrolyte solution is 1%~80%; the electrolyte solution is in order from low to high solid content Coating on one side of the positive electrode and negative electrode, heat treatment after each coating, and finally get the positive electrode and negative electrode with electrolyte layer on one side; Step 4: By winding or stacking, assemble the positive electrode sheet and negative electrode sheet with an electrolyte layer on one side produced in step 3 into an all-solid lithium-ion battery cell, and obtain an all-solid-state lithium-ion battery after hot pressing and packaging. 2. A method for making a high specific energy all-solid-state lithium battery according to claim 1, characterized in that the conductive agent described in step 1 and step 2 is conductive carbon black, conductive graphite, acetylene black, Ketjen black , carbon fiber, carbon nanotube and graphene, and the binder is polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose and styrene-butadiene rubber One or more, the pore forming agent is one or more of ammonium bicarbonate, ammonium acetate, ammonium nitrate and ammonium carbonate. 3. The manufacturing method of a high-specific-energy all-solid-state lithium battery according to claim 1, wherein the positive electrode active material described in step 1 is lithium iron phosphate, nickel-cobalt lithium manganate, nickel-cobalt lithium aluminate 1. One or more of lithium nickel manganese oxide and lithium-rich positive electrode materials, the solvent is N-methylpyrrolidone, and the positive electrode current collector is aluminum foil; In step 2, the negative electrode active material is one or more of graphite, hard carbon and silicon-based materials, the solvent is deionized water, and the negative electrode current collector is copper foil. 4. The manufacturing method of a high-specific-energy all-solid-state lithium battery according to claim 1, wherein the polymer electrolyte in step 3 is polyethylene oxide, polymethyl methacrylate, polypropylene One or more of nitrile series, polyvinylidene fluoride series and polyvinyl chloride series; the filler is nano- _Al2O3 inorganic filler or nano _{- SiO2} inorganic filler or metal-organic framework material organic filler; the lithium salt It is one or more of LiCF ₃ SO ₃ , LiClO ₄ , LiPF ₆ and LiI; the solvent is N-methylpyrrolidone. 5. The manufacturing method of a high-specific-energy all-solid-state lithium battery according to claim 1, wherein the thickness of the polymer electrolyte layer coated on the surface of the positive electrode sheet and the negative electrode sheet in step 3 is 5-50 μm. 6. The manufacturing method of a high-specific-energy all-solid-state lithium battery according to claim 1, wherein the thickness of the polymer electrolyte layer coated on the surface of the positive electrode sheet and the negative electrode sheet in step 3 is 10-20 μm. 7. The manufacturing method of a high-specific-energy all-solid-state lithium battery according to claim 1, wherein the heat treatment temperature in step 1 is 80-140° C., and the treatment time is 60-600 s; the heat treatment temperature in step 2 is 60-60 s. 120°C, the treatment time is 60-600s; in step 3, the heat treatment temperature is 60-120°C, and the treatment time is 60-600s. 8. The manufacturing method of a high-specific-energy all-solid-state lithium battery according to claim 1, wherein the hot-pressing temperature during the assembly of the solid-state lithium battery in step 4 is 80-160°C, and the pressure is 5-10Mpa , the time is 1-200s.