Preparation method of 3D printing customized oxide solid electrolyte and lithium battery

Abstract

The invention discloses a preparation method of a 3D printing customized oxide solid electrolyte and a lithium battery, and the preparation method comprises the following steps: 1, carrying out 3D printing molding on an oxide-based electrolyte, drying, and carrying out high-temperature calcination to obtain an oxide-based skeleton; 2, preparing a PEO-based electrolyte, casting the PEO electrolyte on a polytetrafluoroethylene substrate, laying the inorganic oxide-based skeleton on the polytetrafluoroethylene substrate, drying, carrying out secondary casting of PEO, filling gaps of the oxide-based skeleton, standing and drying to obtain a PEO-oxide-based composite solid electrolyte skeleton, and mixing the PEO-oxide-based composite solid electrolyte skeleton with a positive pole piece, a negative pole piece, a positive pole piece and a negative pole piece to obtain the positive pole piece. And assembling the negative pole piece to obtain the solid-state lithium battery. According to the method, the interface resistance can be reduced, so that the ionic conductivity is improved, and the method has the characteristics of larger electrode-electrolyte interface and shortened ion diffusion length.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery preparation technology, specifically relating to a method for preparing a 3D-printed custom oxide solid electrolyte and lithium battery. Background Technology

[0002] Currently, most commercially available lithium-ion batteries contain liquid electrolytes, which pose fire and explosion risks due to their low boiling and flash points. Solid-state electrolytes can reduce or eliminate these risks, and solid-state lithium batteries can achieve high energy density while ensuring safety.

[0003] However, the poor solid-solid interface contact between the solid electrolyte and electrode materials in solid-state batteries will increase the internal resistance of the battery and reduce its electrochemical performance.

[0004] CN118507824A discloses a polymer / ceramic composite electrolyte, its preparation method, and its application. The electrolyte membrane is prepared using PVDF and PEO as polymer substrates and Zn-doped lithium titanium aluminum phosphate as an inorganic filler. While this method can improve the mechanical strength of the solid electrolyte and increase its ionic conductivity at room temperature, the small size of the Zn-LATP particles makes it difficult to achieve uniform dispersion within the PVDF and PEO polymer substrates. This affects lithium-ion transport, easily causing localized polarization and impacting battery performance. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, the purpose of this invention is to provide a method for preparing 3D printed custom oxide solid electrolytes and lithium batteries, so as to solve one or more of the problems of high interface resistance, low ionic conductivity and local polarization in solid batteries, increase the electrode-electrolyte interface and shorten the ion diffusion length.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a 3D-printed custom oxide solid electrolyte includes the following steps; S1: Dissolve the binder powder in a solvent, add inorganic oxides, stir thoroughly and disperse evenly to obtain ink, and then sieve the ink to obtain printing paste; S2: Using the printing paste, 3D printing is performed to form an oxide solid electrolyte of a predetermined shape on the substrate.

[0007] Preferably, the binder in S1 is CMC (sodium carboxymethyl cellulose), and the inorganic oxide is any one or at least two combinations of LATP, LLZO, LLTO or Al2O3, with a weight ratio of binder to inorganic oxide of (1-10):(10-1).

[0008] Preferably, the solvent in S1 is a mixture of deionized water and acetonitrile, and the weight ratio of deionized water to acetonitrile is (1-5):(5-1).

[0009] Preferably, the conditions for stirring and dispersing in S1 are: The homogenization process under vacuum conditions involved stirring in a homogenizer, with the stirring speed divided into three segments: The first stage should not exceed 100 rpm, and stirring should be carried out for 5 minutes to 1 hour. The second stage involves stirring at 200-300 rpm for 5 minutes to 1 hour. The third stage involves stirring at 500-600 rpm for 8-12 hours. The vacuum level is -0.8 to -1 MPa. The first stage of low-speed mixing is for initial mixing of the slurry. The second stage of medium-speed mixing is for increasing the equipment speed, reducing the equipment load, and avoiding mechanical damage caused by directly mixing high-viscosity slurry at high speed. The third stage of high-speed mixing is for final dispersion, breaking up particle agglomerates through high shear force.

[0010] Preferably, the method for sieving the ink is as follows: The ink is vacuum filtered through a 300-mesh sieve (the higher the mesh number, the better the uniformity of particle dispersion and the better the printing effect) to obtain the printing paste, which is then transferred into the printing barrel; the corresponding printing parameters of the 3D printer are set.

[0011] Preferably, the substrate is an aluminum foil current collector, the 3D printer uses a printing needle with an inner diameter of 210-300µm, moves at a constant speed of 4-15mm / s, the line spacing is set to 200-510µm, and the feeding pressure is 0.1-0.3Mpa.

[0012] Preferably, the printing paste is printed onto the aluminum foil current collector, and after it dries naturally, the skeleton is transferred to a vacuum oven for drying. The parameters of the vacuum drying oven include: vacuum degree of -0.8 to -1.0 MPa, drying temperature of 80 to 120°C, and drying time of 10 to 24 hours. The purpose of setting the drying temperature range is to remove solvents and dry the material, and the drying time setting is to ensure that the material is completely dried.

[0013] After setting the preset shape using the printer's built-in software, you can print it by connecting the printer.

[0014] A method for preparing a lithium battery includes the following steps; Step 1: After 3D printing the oxide solid electrolyte, dry it and then calcine it at high temperature to obtain the oxide-based framework; Step 2: Prepare PEO (polyethylene oxide) based electrolyte and cast the PEO electrolyte onto a polytetrafluoroethylene plate. After laying the inorganic oxide-based skeleton on the upper part of the polytetrafluoroethylene plate and drying it, perform a second casting of PEO to fill the gaps in the oxide-based skeleton. Allow it to stand and dry to obtain a PEO-oxide-based composite solid electrolyte skeleton. Assemble it with the positive electrode and negative electrode to obtain a solid-state lithium battery.

[0015] The calcination temperature in step 1 is 650℃-950℃, and the calcination time is 4-7 hours. This calcination temperature falls within this range when the material is prepared from the precursor to obtain the inorganic oxide.

[0016] Preferably, in step 2 of the method for preparing PEO-based electrolyte, PEO, lithium salt, oxide and plasticizer are dissolved in a solvent in a certain proportion to obtain PEO-based electrolyte.

[0017] By weight, the PEO content is 30-70%; the lithium salt content is 10-25%; the oxide content is 10-20%; and the plasticizer content is 3-5%. The lithium salt is one of lithium bis(trifluoromethanesulfonate)imide, lithium bis(fluorosulfonylimide) or lithium hexafluorophosphate. The plasticizer is succinic acid; The inorganic oxide is any one or at least two of LATP, LLZO, LLTO or Al2O3; The solvent is acetonitrile.

[0018] In step 2, the specific method of secondary casting of PEO is to cast PEO slurry onto the oxide skeleton and automatically level it.

[0019] Preferably, the positive electrode active material is one of lithium iron phosphate material, nickel cobalt manganese ternary positive electrode material, or lithium cobalt oxide positive electrode material, and the negative electrode is a lithium sheet. The battery is assembled into a button cell solid-state battery in a glove box, where the moisture pressure and oxygen partial pressure are both less than 0.1 ppm, and the battery is tested at a temperature of 60°C.

[0020] The beneficial effects of this invention are: (1) The 3D printing oxide-based solid electrolyte prepared by the present invention can achieve structural customization, high printing accuracy and high integration; the 3D printing structure can be customized by setting the structure according to the software program, so as to print the corresponding structure on the 3D printer and achieve the purpose of structural customization.

[0021] (2) The 3D printed oxide-based solid electrolyte prepared in this invention is combined with PEO electrolyte. The inorganic oxide can be fully filled into PEO electrolyte. While improving the mechanical strength of PEO base, the tortuosity of lithium ion transport is reduced through percolation effect, realizing the directional transport of lithium ions, thereby reducing electrochemical impedance and improving battery performance.

[0022] (3) The solid-state battery of the present invention does not contain liquid electrolyte, thus greatly improving the energy density and safety of the battery; the present invention constructs a customized grid electrolyte as a substrate through 3D printing technology, constructs a three-dimensional ion transport network, shortens the lithium ion transport path, solves the problem of uneven dispersion of inorganic oxide electrolyte in PEO, improves the electrochemical compatibility of electrode-electrolyte interface, solves the problem of local polarization, and reduces interface resistance. Attached Figure Description

[0023] Figure 1 The diagram shows the impedance test performance of different types of batteries according to the present invention.

[0024] Figure 2 The graph shows the rate performance of different types of batteries according to the present invention.

[0025] Figure 3 The graph shows the 0.2C cycle test performance of different types of batteries according to the present invention. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings.

[0027] Example 1 This invention relates to a 3D-printed oxide-based solid electrolyte with a customized shape. 13g of water and 5g of acetonitrile are added to a mixing tank as a mixed solvent. 0.51g of binder CMC is weighed and added to the mixed solvent. Vacuum stirring is performed using a homogenizer at a speed of 100r / min for 5min, 300r / min for 5min, and 600r / min for 4h until the powder is fully dissolved. The vacuum degree is -0.8Mpa.

[0028] 4.59 g of inorganic oxide LATP was weighed and added to the above mixed solution. The homogenizer was set to a speed of 100 r / min for 5 min, 300 r / min for 5 min, and 600 r / min for overnight stirring until the powder was fully dissolved, with a vacuum degree of -0.8 MPa. After stirring overnight, the mixture was sieved through a 300-mesh sieve to obtain the printing slurry. The printing slurry was transferred to a printing cylinder, and the 3D printer printing parameters were set to print electrodes on an aluminum foil current collector. The printer used a printing needle with an inner diameter of 210 µm, moving at a constant speed of 15 mm / s, with a line spacing of 510 µm, printing a grid-like electrolyte. The printed electrodes were then vacuum dried in a vacuum oven at 120 °C with a vacuum degree of -0.8 MPa. No high-temperature calcination process was performed, resulting in a 3D-printed oxide-based LATP solid electrolyte with a customized shape.

[0029] 10g of acetonitrile was placed in a glass bottle as a solvent. 0.1g of succinate and 0.4g of LATP were weighed into the solvent and sonicated for 30min, followed by stirring for 1h. After stirring, 1g of PEO was added and stirred at 200r / min overnight. After PEO was fully dissolved, 0.5g of LITFSI was added in a glove box and stirred for 3h to obtain a PEO-based composite solid electrolyte solution.

[0030] PEO composite electrolyte is cast onto a polytetrafluoroethylene plate, and LATP oxide-based skeleton is laid on top and dried. Then, PEO is cast a second time on top to fill the gaps in the oxide-based skeleton. After standing and drying, a PEO-LATP-based composite solid electrolyte skeleton is obtained. The skeleton is then assembled into a battery in the following order: positive electrode shell, positive electrode sheet, PEO-LATP-based electrolyte membrane, lithium metal negative electrode, gasket, spring sheet, and negative electrode shell. The battery is then sealed under a pressure of 1000 psi.

[0031] The solid-state battery was tested for impedance, rate (0.1C, 0.2C, 0.5C, 1C, 2C, 0.1C) and cycle performance (0.2C) at 60°C, with a charge-discharge interval of 2 minutes.

[0032] Example 2 The difference between this embodiment and Embodiment 1 is that, in the preparation of the 3D printing slurry, the ratio of water to acetonitrile was adjusted to 5g water and 13g acetonitrile as a mixed solvent and added to a mixing tank. Then, 4g of binder CMC was weighed and added to the mixed solvent, and the mixture was vacuum stirred using a homogenizer. After stirring, 2g of LATP was added to the above mixed solution. The printed electrode was then vacuum dried at 120°C in a vacuum oven and calcined at 650°C for 6 hours to obtain a 3D-printed oxide-based LATP solid electrolyte with a customized shape.

[0033] Example 3 The difference between this embodiment and Embodiment 1 is that, in the preparation of the 3D printing slurry, the ratio of water to acetonitrile was adjusted to 10g water and 8g acetonitrile as a mixed solvent and added to a mixing tank. Then, 1g of binder CMC was weighed and added to the mixed solvent, and the mixture was vacuum stirred using a homogenizer. After stirring, 5g of LATP was added to the above mixed solution. The printed electrode was then vacuum dried at 120°C in a vacuum oven and calcined at 750°C for 6 hours to obtain a 3D-printed oxide-based LATP solid electrolyte with a customized shape.

[0034] Example 4 The difference between this embodiment and Embodiment 1 is that, in the preparation of the 3D printing slurry, the ratio of water to acetonitrile is adjusted to 10g water and 8g acetonitrile as a mixed solvent and added to a mixing tank. Then, 1g of CMC binder is weighed and added to the mixed solvent, and the mixture is vacuum stirred using a homogenizer. After stirring, 5g of LATP is added to the above mixed solution. The printed electrode is vacuum dried at 120°C in a vacuum oven and calcined at 850°C for 6 hours to obtain a 3D printed oxide-based LATP solid electrolyte with a customized shape. 10g of acetonitrile is used as a solvent in a glass bottle. 0.6g of succinate and 0.2g of LATP are weighed and added to the above solvent. The mixture is ultrasonicated for 30 minutes and then stirred for 1 hour. After stirring, 0.8g of PEO is added and stirred overnight at 200r / min. After the PEO is fully dissolved, 0.4g of LITFSI is added in a glove box and stirred for 3 hours to obtain a PEO-based composite solid electrolyte solution.

[0035] Example 5 The difference between this embodiment and Embodiment 1 is that the printed electrode was vacuum dried at 120°C in a vacuum oven and calcined at 950°C for 6 hours to obtain a 3D-printed oxide-based LATP solid electrolyte with a customized shape. 10g of acetonitrile was used as a solvent in a glass bottle. 0.2g of succinate and 0.4g of LATP were weighed and added to the solvent. The mixture was ultrasonicated for 30 minutes, then stirred for 1 hour. After stirring, 1.2g of PEO was added, and the mixture was stirred overnight at 200 rpm. After the PEO was fully dissolved, 0.2g of LITFSI was added to a glove box and stirred for 3 hours to obtain a PEO-based composite solid electrolyte solution.

[0036] Comparative Example 1 10g of acetonitrile was used as a solvent in a glass bottle. 0.1g of succinate and 0.4g of LATP were weighed and added to the solvent. The mixture was sonicated for 30 min, then stirred at 800 rpm for 1 h. Next, 1g of PEO was weighed and added to the mixture, and stirred thoroughly overnight. After the PEO was fully dissolved, the mixture was transferred to a glove box, and 0.5g of LITFSI was added under an argon atmosphere. The mixture was stirred at 400 rpm for 3 h to obtain a PEO-based solid electrolyte solution.

[0037] PEO-based electrolyte is cast onto a polytetrafluoroethylene plate and dried. The battery is then assembled in the following order: positive electrode shell, positive electrode sheet, PEO-based electrolyte separator, lithium metal negative electrode, gasket, spring sheet, and negative electrode shell. The battery is then sealed under a pressure of 1000 psi.

[0038] The solid-state battery was tested for impedance, rate (0.1C, 0.2C, 0.5C, 1C, 2C, 0.1C) and cycle performance (0.2C) at 60°C, with a charge-discharge interval of 2 minutes.

[0039] Capacity retention rate of different types of batteries after 50 cycles at 0.2C.

[0040] like Figures 1-3 As shown in the test data of the above embodiments and comparative examples, the present invention has excellent electrochemical performance; the discharge specific capacity of the solid lithium battery at 0.1C-2C is very small. Finally, when the rate is set to 0.1C, the battery discharge specific capacity returns to the initial state, indicating that the battery has excellent rate performance; the impedance diagram of the solid battery shows that the impedance of the batteries in Examples 1-5 is less than that of the comparative battery, indicating that the solid battery prepared by the present invention can significantly reduce the lithium-ion transport path and reduce the tortuosity of lithium-ion transport. After 50 cycles at 0.2C, the capacity retention rates of Examples 1-4 and the comparative examples were all above 90%, indicating that under certain post-processing conditions, the performance of solid-state lithium-ion batteries prepared by 3D printing is superior to that of solid-state lithium-ion batteries prepared by traditional methods.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a 3D printed customized oxide solid state electrolyte, characterized in that, Comprise the following steps: S1: Dissolve the binder powder in the solvent, add inorganic oxide, fully stir and disperse uniformly to obtain ink, and sieve the ink to obtain printing slurry; S2: 3D printing is performed using the printing slurry to form an oxide solid electrolyte with a preset shape on a substrate.

2. The method of claim 1, wherein the method is characterized by: The binder in S1 is CMC, the inorganic oxide is any one or at least two combinations of LATP, LLZO, LLTO or Al2O3, and the weight ratio of the binder to the inorganic oxide is (1-10):(10-1).

3. The method of claim 1 or 2, wherein the method is characterized by, The solvent in S1 is a mixed solvent of deionized water and acetonitrile, and the weight ratio of deionized water to acetonitrile is (1-5):(5-1).

4. The method of claim 1, wherein the method is a method of preparing a 3D printed customized oxide solid state electrolyte. The stirring and dispersing conditions in S1 are: The stirring speed of the homogenizer under vacuum conditions is divided into three stages: The first stage is not higher than 100r, stirring for 5min-1h; The second stage is 200-300r, stirring for 5min-1h; The third stage is 500-600r, stirring for 8-12h; The vacuum degree is-0.8~-1Mpa.

5. The method for preparing a 3D-printed custom oxide solid electrolyte according to claim 1, characterized in that, The sieving treatment of the ink is realized by the following method: Vacuum filtration of the ink on a 300-mesh screen to obtain the printing slurry.

6. The method of claim 1, wherein the method is a method of preparing a 3D printed customized oxide solid state electrolyte. The substrate is an aluminum foil current collector, the 3D printer uses a printing needle with an inner diameter of 210-300µm, moves at a constant speed of 4-15mm / s, the line spacing is set to 200-510µm, and the feeding pressure is 0.1-0.3Mpa; The printing slurry is printed onto the aluminum foil current collector, and after natural drying, the skeleton is transferred to a vacuum oven for drying, and the parameters of the vacuum drying oven include: vacuum degree-0.8~-1.0Mpa, drying temperature 80~120℃, drying time 10~24h.

7. A method of producing a lithium battery, characterized by, Comprise the following steps: Step 1: After the oxide solid electrolyte prepared according to any one of claims 1-6 is 3D printed, it is dried and calcined at high temperature to obtain an oxide-based skeleton; Step 2: Prepare a PEO-based electrolyte, and cast the PEO electrolyte on a polytetrafluoroethylene substrate, lay the inorganic oxide-based skeleton on the upper part of the polytetrafluoroethylene substrate, and then perform secondary casting of PEO to fill the voids of the oxide-based skeleton. After drying, a PEO-oxide-based composite solid electrolyte skeleton is obtained, which is assembled with a positive electrode sheet and a negative electrode sheet to obtain a solid-state lithium battery.

8. The method of claim 7, wherein the method is a method of preparing a lithium battery. The calcination temperature is 650℃-950℃, and the calcination time is 4-7h.

9. The method of claim 8, wherein the lithium battery is prepared by a method comprising: In the method for preparing the PEO-based electrolyte in Step 2, PEO, lithium salt, oxide, and plasticizer are dissolved in a solvent according to a certain ratio to obtain a PEO-based electrolyte. ​ The PEO accounts for 30-70% by weight; the lithium salt accounts for 10-25%; the oxide accounts for 10-20%; and the plasticizer accounts for 3-5%; The lithium salt is one of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, or lithium hexafluorophosphate; The plasticizer is butanedinitrile; The inorganic oxide is any one or at least two combinations of LATP, LLZO, LLTO, or Al2O3; The solvent is acetonitrile.

10. The method of claim 7, wherein the method is a method of preparing a lithium battery. In the step 2, the secondary flow casting of PEO is specifically implemented by pouring PEO slurry on an oxide skeleton and automatically leveling; The positive pole piece active substance is one of lithium iron phosphate material, nickel-cobalt-manganese ternary positive pole material and lithium cobaltate positive pole material, and the negative pole is lithium sheet; the button solid-state battery is assembled in a glove box, the water partial pressure and oxygen partial pressure in the glove box are less than 0.1 ppm, and the temperature of the battery during the test is 60 DEG C.

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